Download Section 1 The Circulatory System

Section 1
Section 1
The Circulatory System
Focus
Objectives
Overview
Before beginning this section
review with your students the
objectives listed in the Student
Edition. Students will be able to
describe the structure of the heart
and blood vessels (cardiovascular
system), how these structures function in transporting materials all
around the body, and how materials move into and out of the blood
vessels. Students will also describe
the structure of the lymphatic system, how it picks up excess fluids
in body tissues and returns them to
the cardiovascular, and the role of
the lymphatic system in immunity.
Bellringer
Ask students the following question: Is blood a liquid or a solid?
Then, have them write down what
they think is found in blood. (Many
students will know that plasma
(liquid) and blood cells (solid) are
in blood. Blood also contains water,
hormones, antibodies, nutrients,
oxygen, carbon dioxide, salts, ions,
wastes, and other materials.) Bio 9A
Transport and Distribution
Regardless of your activities—whether you are roller-blading,
swimming, singing, reading, or just sleeping—your body transports
nutrients, hormones, and gases, and it gets rid of wastes. Two body
systems play major roles in these functions. The circulatory system,
Differentiate between
which includes the cardiovascular and lymphatic systems, transarteries, capillaries,
ports these materials to different parts of the body. The respiratory
10A TAKS 2
and veins.
system exchanges gases with the environment—it takes in oxygen,
Relate the function of the
O2, and releases carbon dioxide, CO2.
lymphatic system to the funcThe human cardiovascular system , shown in Figure 1, functions
tions of the cardiovascular
like a network of highways. The cardiovascular system connects the
and immune systems.
10B
TAKS 2 muscles and organs of the body through an extensive system of
Relate each component of
vessels that transport blood, a mixture of specialized cells and fluid.
blood to its function.
10A
The heart, a muscular pump, propels blood through the blood vessels.
TAKS 2
Summarize how a person’s
Different kinds of molecules move through the cardiovascular
blood type is determined.
10A
system:
TAKS 2
● List five types of molecules
that are transported by the
9A
cardiovascular system.
●
●
●
●
Key Terms
cardiovascular system
artery
capillary
vein
valve
lymphatic system
plasma
red blood cell
anemia
white blood cell
platelet
ABO blood group system
Rh factor
1. Nutrients from digested food are transported to all cells in the
body through the blood vessels of the cardiovascular system.
2. Oxygen from the lungs, where the oxygen is taken in, is transported to all cells through blood vessels.
Cardiovascular System
4. Hormones, substances which
help coordinate many activities
of the body, are transported
through blood vessels.
5. The cardiovascular system also
distributes heat more or less
evenly in order to maintain a
constant body temperature. For
example, in a warm environment, blood vessels in the skin
relax to allow more heat to leave
the body. In a cold environment,
blood vessels constrict, conserving heat by diverting blood to
deeper tissues. This diversion of
blood prevents heat from escaping the body.
Motivate
Activity
GENERAL
Circulatory Function Ask students to name possible functions of
the circulatory system, and write
them on the board. (The circulatory
system carries oxygen, carbon dioxide, nutrients, hormones, cells of the
immune system, wastes, and other
materials; and it is involved in regulating body temperature.) LS Verbal
TAKS 2 Bio 10A
pp. 872–873
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 9A, 10A, 10B
Teacher Edition
TAKS Obj 3 Bio 4C
TAKS Obj 2 Bio 10A
TEKS Bio 4C, 5C, 9A, 10A, 11C
872
3. Metabolic wastes, such as carbon
dioxide, are transported through
blood vessels to the organs and
tissues that excrete them.
Figure 1 Blood vessels,
blood, and a heart.
The cardiovascular system
transports materials
throughout the body and
distributes heat.
872
Chapter Resource File
• Lesson Plan GENERAL
• Directed Reading
• Active Reading GENERAL
• Data Sheet for Quick Lab
GENERAL
Transparencies
TT Bellringer
TT Cardiovascular System
TT Blood Vessels
Chapter 38 • Circulatory and Respiratory Systems
Planner CD-ROM
• Reading Organizers
• Reading Strategies
• Occupational Application Worksheet
Blood-Bank Technologist GENERAL
Blood Vessels
Blood circulates through the body through a network of vessels.
Arteries (AHRT uh reez), shown in Figure 2, are blood vessels that
carry blood away from the heart. Blood passes from the arteries
into a network of smaller arteries called arterioles (ahr TIHR ee
ohls). Eventually, blood is pushed through to the capillaries.
Capillaries are tiny blood vessels that allow the exchange of
gases, nutrients, hormones, and other molecules in the blood. The
molecules are exchanged with the cells of the body. From the capillaries, the blood flows into small vessels called venules (VEHN
yools). From the venules, blood empties into larger vessels called
veins (vaynz). Veins are blood vessels that carry the blood back to
the heart.
Reviewing Information
You can remember that
arteries take blood away
from the heart and veins
carry blood toward the heart
by remembering the letter a
at the beginning of the word
artery and at the beginning
of the word away.
Arteries
With each contraction, the heart forcefully ejects blood into arteries.
To accommodate each forceful pulse of blood, an artery’s wall
expands and then returns to its original size. Elastic fibers in the
walls of arteries allow arteries to expand.
The wall of an artery is made up of three layers of tissue, as
shown in Figure 2. The innermost layer is a thin layer of epithelial
tissue called the endothelium. The endothelium is made up of a
single layer of cells. Surrounding the endothelium is a layer of
smooth muscle tissue with elastic fibers. Finally, a protective layer
of connective tissue with elastic fibers wraps around the smooth
muscle tissue. Just as a balloon expands when you blow more air
into it, the elastic artery expands when blood is pumped into it.
Magnification: 1,150ⴛ
Figure 2 Blood vessels
Blood vessels transport blood and allow for the exchange of substances.
Capillaries
(exchange gases, nutrients,
wastes, and hormones)
Teach
Teaching Tip
GENERAL
Blood-Brain Barrier Provide
students with the information contained in the Medicine Connection
feature at the bottom of this page.
Point out that, while the exclusion
of most chemicals from the brain is
advantageous, it can be a serious
problem when physicians try to
treat disorders involving the brain
and brain function. A major difficulty in treating brain tumors, for
example, is that most of the chemical agents used to treat cancer
cannot reach targets across the
blood-brain barrier. The bloodbrain barrier also prevents most of
the anti-retroviral drugs now used
to treat AIDS from entering the
central nervous system. In addition
to infecting cells of the immune
system, HIV directly infects cells
within the brain itself and the
blood-brain barrier prevents these
drugs from battling HIV-infected
cells in the brain.
TAKS 3 Bio 4C; Bio 5C, 11C
Using the Figure
Arteriole
(connects arteries
to capillaries)
Venule
(connects veins
to capillaries)
Connective tissue
Smooth muscle
Endothelium
Valve
Artery
(carries blood away from the heart)
Vein
(returns blood to the heart)
873
Direct students’ attention to
Figure 2. Point out that veins have
a much wider inside diameter than
arteries. This difference relates to
the differences in function of these
two kinds of vessels. Arteries transport blood away from the heart
under high pressure and force it
into tiny capillaries. Veins transport
blood rapidly and under low pressure back to the heart. Point out
the thicker muscular wall of the
artery in the figure. Also point out
the valve located in the vein.
TAKS 2 Bio 10A
MEDICINE
CONNECTION
The blood-brain barrier is made up of a single layer of endothelial cells that are tightly
packed together and line the inner surfaces of
capillaries in the brain. Endothelial cells in
other parts of the body have gaps between
them through which water, ions, molecules,
and even some blood cells can easily diffuse.
Water is the only constituent of the blood
that can diffuse freely across the blood-brain
barrier. Substances required by the brain,
such as glucose and other nutrients, are
actively transported into the fluid surrounding the brain cells.
This barrier’s most important function is to
provide neurons with the exact amount of glucose they need. If glucose levels go up or down
even slightly, neurons can begin to malfunction.
The blood-brain barrier also maintains a precise
balance of necessary ions within the brain. The
connections between neurons are sensitive to
ion concentrations, and even minor changes
can affect nerve transmission. Bio 5C, 9A, 11C
READING
SKILL
BUILDER
Interactive Reading Assign
Chapter 38 of the Holt Biology
Guided Audio CD Program to help
students achieve greater success in
reading the chapter.
Chapter 38 • Circulatory and Respiratory Systems
873
Capillaries
Real Life
Teach, continued
continued
Real Life
Answer Bio 11C
Student answers will vary, but
should indicate that in general
exercise increases circulation.
Demonstration
Show the class a picture of a person
in a hospital bed. Ask why hospital
workers try to get patients to walk,
if only for a few minutes each day.
(Students should recognize that muscle
movements squeeze the walls of veins,
thus preventing blood from accumulating and clotting in parts of the body
such as the legs. Other methods of
enhancing circulation used in hospitals
include special compression hoses and
pumps that promote blood flow
through the lower extremities.) Ask
students what happens to them if
they stand in one place for a long
period of time, as during a school
assembly or concert. (Most will have
experience some discomfort and possibly dizziness if they have stood for a
long time.) Tell students that they can
help move blood back to the heart
while standing if they repeatedly
bend their legs at the knees.
TAKS 2 Bio 10A, 10B
How long are all of your
capillaries?
If all of the capillaries of
your body were laid end to
end, they would extend all
the way across the United
States! The network of
capillaries in the body
is several thousand
miles long.
Finding Information
Find out how capillaries
respond to long-term
aerobic training.
11C
No cell in your body is more than a few cell diameters away from a
capillary. At any moment, about 5 percent of your blood is in capillaries. In capillaries, gases, nutrients, hormones and other molecules are transferred from the blood to the body’s cells. Carbon
dioxide and other wastes are transferred from the body’s cells to the
capillaries.
The extensive back-and-forth traffic in the capillaries is possible
because of two key properties. Capillary walls are only one cell
thick, so gas and nutrient molecules easily pass through their thin
walls. Capillaries are also very narrow, with an internal diameter of
about 8 µm (0.0003 in.)—a diameter only slightly larger than the
diameter of a red blood cell. Thus, blood cells passing through a capillary slide along the capillary’s inner wall, as shown in the photo in
Figure 2. This tight fit makes it easy for oxygen and carbon dioxide
to diffuse to and from red blood cells through the capillaries.
Veins
The walls of veins consist of a much thinner layer of smooth muscle,
than the walls of arteries. They are farther from the heart pump and
exposed to lower pressures. Veins do not receive the pulsing pressure that arteries do.
As shown in Figure 2, veins also differ from arteries in that
they are larger in diameter. A large blood vessel offers less resistance to blood flow than a narrower one, so the blood can move
more quickly through large veins. The largest veins in the human
body are about 3 cm in diameter—about the same diameter as
your thumb.
Most veins have one-way valves. A valve is a flap of tissue that
ensures that the blood or fluid that passes through does not flow
back. Valves in veins, such as the one shown in Figure 3, prevent the
Figure 3 Valves in veins.
blood from flowing backward during its trip to the heart. When the
Valves are most abundant
in the veins of the arms
skeletal muscles in your arms and legs contract, they squeeze
and legs, where the upward
against the veins, causing the valves to open and thus, allowing the
flow of blood is opposed
blood to flow through. When the skeletal muscles relax,
by gravity.
Magnification: 122ⴛ
the valves close, preventing the backflow of blood.
Sometimes the valves in the veins become weak and the
veins become dilated (larger in diameter). Veins that are
dilated because of weakened valves are called varicose
veins. Dilated veins that occur in the anal area are called
hemorrhoids.
Lymphatic System
Because the blood plasma is rich in proteins, most of the
fluid remains in the capillaries due to osmotic pressure.
However, every time the heart pumps, some fluids are
forced out of the thin walls of the capillaries. The fluid
that does not return to the capillaries collects in spaces
around the body’s cells. The fluid that collects around the
874
pp. 874–875
Student Edition
TAKS Obj 1 Bio/IPC 2B, 2C
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B, 11C
TEKS Bio/IPC 2B, 2C
Teacher Edition
TAKS Obj 1 Bio/IPC 2B, 2C
TAKS Obj 2 Bio 4B, 10A, 10B
TAKS Obj 5 IPC 4A, 4B
TAKS Obj 5 IPC 6B
TEKS Bio 4B, 5A, 10A, 10B, 11C
TEKS Bio/IPC 2B, 2C
TEKS IPC 6B
874
IPC Benchmark Fact
Remind students that as the circulatory system distributes heat throughout the body, energy transfers from
the particles of one object to the particles of another
object because of their different temperatures. When
the energy transfer or heat flows, it moves from the
hotter object to the cooler object. TAKS 5 IPC 6B
Chapter 38 • Circulatory and Respiratory Systems
IPC Benchmark Mini-Lesson
IPC Skills TAKS 5 IPC 4A, 4B
Calculate speed in systems such as the human body.
Investigate applications of Newton's laws.
Activity Tell students that there is an inverse relationship between pressure and flow rate. The faster
a fluid flows through a tube, the lower the pressure
the fluid exerts on the walls of the tube. Blood flows
faster through capillaries than it does through arteries. Using this information have students explain why
capillary walls can withstand the pressure resulting
from blood flowing through them.
Mapping the Valves
in Veins 2B 2C 10A TAKS 1
Teaching Tip
TAKS 2
By applying pressure to your arm, you can locate
the valves in the veins of your arm.
Materials
nontoxic felt-tip pen
Procedure
1. Have a classmate make a fist
and extend his or her arm,
with the hand palm up and
slightly below elbow level.
Locate a prominent vein on
the inside of the forearm.
Using one finger, press down
on the vein at a point near the
wrist to block the blood flow.
Analysis
2. Gently place a second finger
along the vein about 5 cm
from the first finger (toward the
elbow). Release the second
finger, but not the first. The
vein should refill partway. Mark
this point, which indicates the
location of a valve, with a pen.
You may have to try more than
one vein to locate a valve.
cells is picked up by the lymphatic system and
returned to the blood supply.
The lymphatic system collects and recycles fluids
leaked from the cardiovascular system and is involved
in fighting infections. As shown in Figure 4, the
lymphatic system is made up of a network of vessels
called lymphatic vessels and tiny bean-shaped structures called lymph nodes. Lymph tissue is also located
in various places throughout the body, including the
thymus, tonsils, spleen, and bone marrow.
Lymphatic vessels carry the leaked fluid, called
lymph, back to two major veins in the neck. Similar to
veins, lymphatic vessels contain valves that prevent the
backflow of the fluid. The fluid is pushed through
the lymphatic vessels when the skeletal muscles in the
arms and legs contract.
The lymphatic system also acts as a key element in
the immune system. Immune cells in the lymph nodes
and lymphatic organs help defend the body against
bacteria, viruses, other infecting microbes, and cancerous cells. Lymph nodes, which are concentrated in
the armpits, neck, and groin, sometimes get tender
and swell when they are actively fighting infection
and filled with white blood cells. Health-care professionals are trained to detect certain types of
infections by feeling for the lymph node swellings on
the body.
1. Identify the direction blood
flows in the vein you chose.
2. Propose why the subject
must make a fist and hold his
or her arm slightly down.
3. Infer what effect standing in
one place for long periods of
time might have on the veins
in the legs.
Lymphatic System
Tonsils
Thymus
Using the Figure
GENERAL
Direct students’ attention to
Figure 4. Have them examine the
vessels and lymph nodes, including
the tonsils and spleen. Ask them to
identify some ways in which the
lymphatic system is different from
the cardiovascular system. (The
lymphatic system does not run in a
circuit, as the cardiovascular system
does. The lymphatic system also
does not have its own pump, like the
heart of the cardiovascular system.)
TAKS 2 Bio 10A
Lymph node
Spleen
Mapping the
Valves in Veins
TAKS 1 Bio/IPC 2B, 2C; TAKS 2 Bio 10A
Lymphatic vessel
Skills Acquired
Inferring relationships,
identifying functions
Bone marrow
Teacher’s Notes
Instruct students to allow their
arms and hands to hang in
a relaxed manner for 1 to 2
minutes before beginning the
experiment. This demonstration
will also work on the veins in
the back of the hand.
Figure 4 Lymphatic tissues. Lymphatic
tissues are located throughout the body.
875
REAL WORLD
CONNECTION
Cancer is a group of related diseases that
occur when cells keep dividing but new cells
are not needed. These extra cells may form a
mass of tissue, called a tumor. Tumors can be
either benign (not cancerous) or malignant
(cancerous). Cancer can begin in any organ or
tissue of the body. The original tumor is called
the primary tumor and is usually named for
the part of the body where it begins.
Metastasis means the spread of cancer. Cancer
cells can break away from a primary tumor and
Stability and Homeostasis Point
out to students that swollen lymph
nodes contain large numbers of
immune system cells (white blood
cells) that are actively engulfing
bacteria or virus particles. For this
reason, the nodes become inflamed
and tender when the body is fighting an infection. TAKS 2 Bio 4B
travel through the bloodstream or lymphatic
system to other parts of the body. Cancer cells
may spread to lymph nodes near the primary
tumor. Cancer cells can also spread to other
parts of the body, distant from the primary
tumor. Doctors use the term metastatic disease
or distant disease to describe cancer that spreads
to other organs or to lymph nodes other than
those near the primary tumor. When cancer cells
spread and form a new tumor, the new tumor is
called a secondary, or metastatic, tumor.
The effect will be more pronounced if the blood is
squeezed out of the vein
between the first and second
finger. Have students do this by
gently stroking the vein toward
the heart.
Answers to Analysis
1. toward the elbow, and so
toward the heart
2. Blood will have to go against
gravity, enlarging the vein
slightly.
3. Blood will pool in the veins in
the legs.
TAKS 2 Bio 4B; Bio 5A
Chapter 38 • Circulatory and Respiratory Systems
875
Components of Blood
Teach, continued
continued
SKILL
BUILDER
Math Skills A human adult has
about 5 L (1.25 gal) of blood.
Plasma is more than 90 percent
water. The body contains some 30
trillion red blood cells and about
60 billion white blood cells. Every
second about 2 million new red
blood cells are made in the bone
marrow to replace those that die at
the end of their 120-day life span.
Have students calculate how many
new red blood cells are made every
hour. ([2,000,000 cells/s] [60 s/min] [60 min/h] 7,200,000,000 cells/h) LS Logical
Real Life
Several proteins from
vampire bats stop blood
from clotting.
These proteins, including
one named draculin, are
being used to develop
drugs to fight heart
disease.
Finding Information
Investigate other drugs
that are currently being
developed to help fight
heart disease.
11C
pp. 876–877
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B, 11C
Teacher Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 6C
TAKS Obj 2 Bio 10A
TEKS Bio 3E, 4B, 5A, 5C, 6C,
11C, 11D
876
Water Water in the plasma acts as a solvent. It carries other
and other nutrient molecules. Vitamins, hormones, gases, and
nitrogen-containing wastes are also found in plasma.
Salts (Ions) Salts are dissolved in the plasma as ions. The chief
plasma ions are sodium, chloride, and bicarbonate. The ions have
many functions, including maintaining osmotic balance and regulating the pH of the blood and the permeability of cell membranes.
Proteins Plasma proteins, the most abundant solutes in plasma,
Figure 5 The river of life.
The loss of too much blood
can create a life-threatening
situation.
Demonstration
Bio 3E, Bio 5A
About 60 percent of the total volume of blood is plasma, the liquid
portion of blood. Plasma is made of 90 percent water and 10 percent
solutes. The solutes include metabolites, wastes, salts, and proteins.
substances.
Real Life
Answer Bio 11C
Add red water to a test tube to
make it about 40 percent full. Then
carefully add vegetable oil until the
test tube is full. Explain to students
that the fluids in the test tube
resemble a centrifuged blood sample. Centrifuging pulls the heavier
components to the bottom of the
tube. Lighter components stay at
the top. The vegetable oil represents plasma, a yellow fluid. The
red water represents red blood
cells. Note that platelets and white
blood cells, normally found
between the two layers, are not
represented in this model. LS Visual
Plasma
Metabolites and Wastes Dissolved within the plasma are glucose
TAKS 2 Bio 4B
Student answers will vary, but
should be well researched.
Students should present their
research results to the class.
Blood has been called the river of life because it is responsible for
transporting so many substances throughout the body. In lifethreatening situations, a person’s blood volume is carefully monitored, as shown in Figure 5. Typically, blood appears to us as a red,
watery fluid. Blood is composed of water, but it also contains a variety of molecules dissolved or suspended in the water, as well as
three kinds of cells.
play a role in maintaining the osmotic balance between the cytoplasm of cells and that of plasma. Water does not move by osmosis
from the plasma to cells because the plasma is rich in dissolved proteins. In fact, the total amount of protein in cells and in plasma is
the same, making cytoplasm and plasma essentially isotonic with
respect to each other.
Some plasma proteins help thicken the blood. The thickness of
blood determines how easily it flows through blood vessels. Other
plasma proteins serve as antibodies, defending the body
from disease. Still other plasma proteins, called clotting proteins or blood-clotting factors, play a major role in blood
clotting. When blood is collected for clinical purposes, the
blood-clotting factors are removed from the blood and stored
for later use.
Blood Cells and Cell Fragments
About 40 percent of the total volume of blood is cells and cell
fragments that are suspended in the plasma. There are three
principal types of cells in human blood: red blood cells, white
blood cells, and platelets.
Red blood cells Most of the cells that make up blood are
red blood cells —cells that carry oxygen. Each milliliter of
human blood contains about 5 million red blood cells. Red
blood cells are also called erythrocytes (eh RIHTH roh seyets).
876
MISCONCEPTION
ALERT
The Color of Blood Students might think
that blood is one of two colors, red or blue.
Diagrams that portray bright red arteries
and deep blue veins may enhance students’
confusion. Oxygenated blood is, in fact,
scarlet in color, while deoxygenated blood
is maroon, closer to dark red than to blue.
The blue color seen in the superficial veins
of a person with fair skin is misleading: the
skin and connective tissue that overlie the
veins distort the true color of the blood
within the veins. Bio 5A
Chapter 38 • Circulatory and Respiratory Systems
INCLUSION
Strategies
• Learning Disability
• Attention Deficit
Disorder
Have students create a poster or bulletin
board of the Lymphatic System. Using
Figure 4, have students label the different
lymphatic tissues found in the body. They
may add note cards describing the function
of each of the tissues and attach them to the
poster or bulletin board. They may be able
to present their findings to the class and be
able to tell how doctors use lymph nodes to
detect infection. TAKS 2 Bio 10A; Bio 3E
Using the Figure
Red blood cells
White blood cell
Platelets
Most of the interior of a red blood cell is packed with hemoglobin. Hemoglobin is an iron-containing protein that binds oxygen
in the lungs and transports it to the tissues of the body. Mature red
blood cells do not have nuclei and therefore cannot make proteins
or repair themselves. The absence of a nucleus gives a red blood cell
its biconcave shape, as shown in Figure 6, and a short life span
(about 4 months). New red blood cells are produced constantly by
stem cells, specialized cells in bone marrow.
An abnormality in the number or function of red blood cells can
result in anemia. Anemia (uh NEE mee uh) is a condition in which
the oxygen-carrying ability of the blood is reduced. Anemia may
result from blood loss or nutritional deficiencies.
Figure 6 Three kinds of
blood cells. Red blood cells
transport oxygen and some
carbon dioxide. White blood
cells help defend the body
against disease. Platelets are
involved in blood clotting.
Activity
TAKS 2 Bio 4B
Group Activity
www.scilinks.org
Topic: White Blood Cells
Keyword: HX4190
Graphic Organizer
Blood
GENERAL
Blood Composition Blood has
several different components, and
learning them can be confusing.
Have students construct a
Graphic Organizer, such as the
one shown at the bottom of this
page, that describes the structure
and function of each of the blood
components discussed in the text.
Students should also show the
composition of plasma, the fluid
portion of the blood. LS Visual
877
Use this graphic organizer
with Activity on this page.
Refer students to Figure 6. Have
students relate the shapes and sizes
of the cells and cell fragments in
the figure to their functions. (Red
blood cells have a large surface area
for gas diffusion, and the characteristic “donut” shape enables them to
squeeze through tiny capillaries. The
shape of the white blood cells enables
them to engulf other particles, and
their size ensures that they can defend
the body against a large number of
invaders. The shape of the platelets
allows them to stick together to form
a small plug.) Have students compare the pictures with prepared
microscope slides of human blood.
LS Visual TAKS 2 Bio 4B; Bio 5A, 5C
White Blood Cells There are only 1 or 2 white blood cells, or
leukocytes (LOO koh sites), for every 1,000 red blood cells.
White blood cells are cells whose primary job is to defend the body
against disease. White blood cells, shown in Figure 6, are larger
than red blood cells and contain nuclei.
There are many different kinds of white blood cells, each with a
different immune function. For example, some white blood cells
take in and then destroy bacteria and viruses. Other white blood
cells produce antibodies, proteins that mark foreign substances for
destruction by other cells of the immune system.
Platelets In certain large cells in bone marrow, bits of cytoplasm
are regularly pinched off. These cell fragments, called platelets
(PLAYT lihts), are shown in Figure 6. Platelets play an important
role in the clotting of blood. If a hole develops in a blood vessel
wall, rapid action must be taken by the body, or blood will leak out
of the system and death could occur.
When circulating platelets arrive at the site of a broken vessel,
they assume an irregular shape, get larger, and release a substance
that makes them very sticky. The platelets then attach to the protein
fibers on the wall of the broken blood vessel and eventually form a
sticky clump that plugs the hole.
GENERAL
Platelets—blood clotting
Metabolites
White blood cells—defend
body against disease
Wastes
Plasma—liquid portion of blood
Salts
Red blood cells—carry oxygen
Proteins
Blood Diseases Have students
work in small groups to conduct
library or Internet research on diseases and disorders of the blood
and blood vessels. (Some examples
of diseases they could investigate
include cancers such as leukemia
and lymphoma, anemia, sickle-cell
disease, hemophilia, Raynaud’s
phenomenon, thalassemia, and von
Willebrand disease.) Students
should collect information on the
causes, symptoms, treatment, and
other pertinent information. Have
each group prepare a report to
present to the entire class.
TAKS 2 Bio 6C; Bio 11D
Chapter 38 • Circulatory and Respiratory Systems
877
For wounds such as an open cut, the platelets
release a clotting enzyme that activates a series of
chemical reactions. Eventually, a protein called fibrin is formed. The fibrin threads form a net, trapping
blood cells and platelets, as shown in Figure 7. The
net of fibrin and platelets develops into a mass, or
clot, that plugs the blood vessel hole. A mutation in
a gene for one of the blood-clotting proteins causes
hemophilia, a blood clotting disorder.
Figure 7 Blood-clotting cascade
Teach, continued
continued
Teaching Tip
Blood Clotting Tell students that
when people cut themselves shaving,
they often put a piece of tissue over
the cut. The fibers in the tissue act
like platelets, beginning the clotting
process by providing a framework
for red blood cells to be caught.
The release of enzymes
from platelets at the site
of a damaged blood
vessel initiates a
“clotting cascade.”
Stimulus
Blood vessel
damage
Platelets release
clotting protein
(enzyme)
Blood Type
Fibrin net
Blood cells
Occasionally, an injury or disorder is so serious
that a person must receive blood or blood components from another person. The blood types of the
recipient, the person receiving the blood, and that
of the donor, the person giving the blood, must
match. Blood type is genetically determined by the
presence or absence of a specific complex carbohydrate found on the surface of red blood cells.
One system used to type blood is the
ABO blood group system. Under this system, the
primary blood types are A, B, AB, and O. The letters A and B refer to complex carbohydrates on
the surface of red blood cells that act as antigens,
substances that can provoke an immune response.
Clotting
reaction occurs
TAKS 2 Bio 4B
Fibrin net forms,
trapping blood cells
and platelets
Blood Doping
TAKS 2 Bio 4B, 10A
Teaching Strategies
Bring in articles about other
performance-enhancing (but
often prohibited) practices,
such as the use of steroids and
certain nutritional supplements
for athletes. Explain how they
help an athlete’s performance
but harm an athlete’s health.
Discussion
• Why do you think the plasma
is reinjected immediately? (to
keep blood volume constant)
• Explain the physiological
effects of blood doping and
the reasons for these effects.
(increased endurance due to
more oxygen in the blood;
decreased heart rate; decreased
lactic acid in muscles due to
increased oxygen, increased aerobic respiration, and decreased
anaerobic respiration)
• Why would doped blood clot
more easily? (There are more
solids in it.)
Result
Blood clot
Blood Doping
M
ost athletes try to gain an
edge over their competitors
through conditioning programs
and longer hours in training.
Some, however, turn to artificial
methods, such as blood doping.
What Is Blood Doping?
Blood doping is a practice used
by some athletes to increase the
amount of oxygen their blood can
carry by elevating the number of
red blood cells in their body. Several months before a competition,
some of the athlete’s blood is
drawn. The plasma is separated
from the cells. The blood cells are
frozen. The plasma is immediately injected back into the
athlete’s bloodstream.
TAKS 2
The body senses its deficiency
of red blood cells, and steps up its
production of red blood cells. After
1 to 2 months, the entire procedure may be repeated. A few days
before an athletic competition, the
frozen blood cells are thawed and
injected into the athlete, temporarily bringing the athlete’s red blood
cell count above normal.
Does Blood Doping Work?
Athletes who use blood doping
show an increase in endurance
while running on a treadmill, a
decrease in their heart rate during
exercise, and a reduction in the
level of lactic acid in their blood.
The Risks of Blood Doping
The risks of blood doping far
outweigh the benefits. The blood
clots more easily, raising the
risks of heart attack and stroke.
Air bubbles are sometimes accidentally injected, and blood cells
are sometimes contaminated
while out of the body.
Athletes who inject blood
cells taken from another person
face the dangers of blood incompatibility and transmission
of diseases, including AIDS and
hepatitis. For these and other
reasons, blood doping has been
prohibited by many sportsgoverning bodies.
878
Transparencies
TT Blood Clotting Cascade
TT Systemic Circulation
pp. 878–879
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B
Teacher Edition
TAKS Obj 2 Bio 4B, 10A, 10B
TEKS Bio 4B, 10A, 10B
TEKS Bio/IPC 3C
878
TECHNOLOGY
CONNECTION
Since uncontrolled bleeding is the most common
cause of death for soldiers wounded on the battlefield, military medical researchers have long
sought improved bandages that can be used in
the front lines. Army medical researchers have
helped to develop an improved field bandage
that can reduce bleeding by as much as 85
percent compared to previous dressings. Now
undergoing testing, the new bandage contains
blood-clotting proteins. It is about four inches
square and a quarter of an inch thick. The
Chapter 38 • Circulatory and Respiratory Systems
blood clotting proteins are imbedded in a
film, which is freeze-dried onto the bandage.
The bandage is pressure-applied, which helps
activate its clotting agents, which set in about
a minute. The bandage is lightweight and can
be stored at room temperature, but it must be
packed in a watertight seal or it will “clot” in
the bag by absorbing water from the air. Dry
bandages retard chemical breakdown and
negate the need for refrigeration, important
characteristics for a field dressing. Bio/IPC 3C
Table 1 Blood Types
Blood
type
Antigen on the
red blood cell
Antibodies
in plasma
Can receive
blood from
Can donate
blood to
A
A
B
O, A
A, AB
B
B
A
O, B
B, AB
AB
A, B
Neither A nor B
O, A, B, AB
AB
O
Neither A nor B
A, B
O
O, A, B, AB
As summarized in Table 1, people with type A blood have the
A antigen on their red blood cells. People with type B blood have the
B antigen. People with type AB blood have both the A and the B
antigen, while those with type O blood have neither antigen.
Antibodies are defensive proteins made by the immune system. People with type A blood produce antibodies against the B antigen, even
if they have never been exposed to it. In these people, type B red blood
cells clump and can block blood flow. For this reason, blood transfusion recipients must receive blood that is compatible with their own.
People with type AB blood are universal recipients (they can
receive A, B, AB, or O blood) because they do not have anti-A or
anti-B antibodies. Type O individuals are universal donors (they can
donate blood to those with A, B, AB or O blood) because their blood
cells do not carry A or B antigens and therefore do not react with
either anti-A or anti-B antibodies.
Rh Factor
Another important antigen on the surface of red blood cells is
called Rh factor, which was originally identified in rhesus monkeys. People who have this protein are said to be Rh, and those
who lack it are Rh. When an Rh mother gives birth to an Rh
infant, the Rh mother begins to make anti-Rh antibodies. The
mother’s antibodies may be passed to an Rh fetus in a future pregnancy, which can lead to fetal death.
www.scilinks.org
Topic: Cardiovascular
Research in Texas
Keyword: HXX4005
Reteaching
Have students observe prepared
slides of normal blood and blood
with abnormalities such as
leukemia (cancer of the white
blood cells) or an iron deficiency.
Have them compare and contrast
what they see. (With leukemia, the
number of white cells may be greater.
An iron deficiency may cause the red
cells to be lighter in color and fewer
in number.) TAKS 2 Bio 4B
Quiz
involved in the exchange of
materials between the blood and
body tissues? (capillaries)
Real Life
TAKS 2 Bio 10B
RhoGAM is a blood
product that can suppress the ability to
respond to Rhⴙ red
blood cells.
It is given to an Rh
woman who is pregnant
with an Rh fetus to prevent her from developing
antibodies that would
harm her baby.
2. What happens to excess fluid
that collects in body tissues?
(It is picked up in lymph vessels
and returned to the cardiovascular
system.) TAKS 2 Bio 10B
3. Which type of blood cell is the
smallest whole cell?
(red blood cell) TAKS 2 Bio 4B
Alternative
Assessment
Name the system that transports nutrients, oxygen,
Predict the blood types that would be safe for
wastes, hormones, and heat.
a person with type A blood to receive during a
10A 10B
transfusion.
10A 10B
Compare the structures and functions of
10A
Describe the role of the lymphatic system.
10A
Summarize the functions of water, red blood
cells, white blood cells, and platelets.
10B
TAKS Test Prep Which antigens are on the red
10A
blood cells of a person with type O blood.
A 0 antigens
C Either A or B antigens
B Both A and B
D Neither A nor B
antigens
antigens
879
Answers to Section Review
1. the cardiovascular system TAKS 2 Bio 10A, 10B
2. arteries—thick, elastic walls and thick smooth
muscle layers that carry blood under high pressure away from the heart; veins—thin walls
and thin smooth muscle layers that carry blood
under low pressure to heart; capillaries—thin
walls that allow exchange of substances in the
blood with the tissues TAKS 2 Bio 10A
3. The lymphatic system collects and recycles fluids leaked from the circulatory system and is
involved in fighting infections. TAKS 2 Bio 10A
GENERAL
1. Which type of blood vessel is
Section 1 Review
arteries, capillaries, and veins.
Close
4. Water is the solvent for dissolved substances in
the blood. Red blood cells carry oxygen to body
tissues. White blood cells defend the body
against pathogens. Platelets help keep the venous
system intact by patching tears in blood vessels.
GENERAL
Have students explain the adaptive
value of the location of arteries
(generally found far below the
body’s surface), veins (located
closer to the surface), and capillaries (distributed all over the body).
(Arteries carry blood under high
pressure, so a tear or rupture is more
life threatening than it is in a vein.
Therefore it is beneficial to protect
arteries deep within the body.
Capillaries must come into contact
with every cell in the body to perform
their exchange function.)
TAKS 2 Bio 10A
TAKS 2 Bio 10B
5. A and O are both safe. TAKS 2 Bio 10A, 10B
6.
A. Incorrect. There are no
O antigens. B. Incorrect. Both antigens are
not present. C. Incorrect. Neither antigen is
present. D. Correct. Type O has neither A
nor B antigens. TAKS 2 Bio 10A
Chapter 38 • Circulatory and Respiratory Systems
879
Section 2
Section 2
The Heart
Focus
Objectives
Overview
Before beginning this section
review with your students the
objectives listed in the Student
Edition. Students will map how the
structures of the cardiovascular system pump blood around the body.
They will also describe electrical
activity in the heart. Finally, they
will list some disorders of the heart.
Bellringer
Ask students to write a few sentences that describe how the muscle
tissue of the heart is different from
other types of muscle tissue.
(Answers may vary.)
● Differentiate the pulmonary
circulation loop from
the systemic circulation
loop.
10A TAKS 2
● Summarize the path that
blood follows through the
heart.
10A TAKS 2
A Muscular Pump
Blood vessels allow for the movement of blood to all cells in the
body. The pumping action of the heart, however, is needed to provide enough pressure to move blood throughout the body. The heart
is made up mostly of cardiac muscle tissue, which contracts to
pump blood.
Two Separate Circulatory Loops
● Name the cluster of heart
cells that initiates contraction
10A TAKS 2
of the heart.
As shown in Figure 8, the human heart has two separate circulatory
loops. The right side of the heart is responsible for driving the pulmonary (PUHL muh nehr ee) circulation loop, which pumps
oxygen-poor blood through the pulmonary arteries to the lungs.
● Describe three ways to
monitor the health of the
Gas exchange—the release of carbon dioxide and pick up of oxycirculatory system.
10A TAKS 2 gen—occurs in the lungs. The oxygenated blood is then returned to
the left side of the heart through pulmonary veins.
● Name two vascular diseases,
The left side of the heart is responsible for driving the systemic
and identify factors that
contribute to their
circulation loop, which pumps oxygen-rich blood through a netdevelopment.
11C
work of arteries to the tissues of the body. Oxygen-poor blood is
then returned to the right side of the heart through the veins.
Key Terms
TAKS 2 Bio 10A; Bio 5A
Motivate
Demonstration
Show students that when blood is
far from the heart, it travels with
less pressure. You will need plastic
syringes and two pieces of hosing
that fit snugly on their ends. One
hose should be about 8 cm (3 in.)
long and the other about 15 cm
(6 in.). Fill each syringe and force
the water out. The stream should
travel about 8 to 15 cm (3 to 6 in.)
from the end of the longer hose
(vein), and 15 to 30 cm (6 to
12 in.) from the end of the shorter
hose (capillary). Be sure to apply
equal pressure to the plunger each
time so students appreciate the fact
that it is distance from plunger tip
to exit, not pressure on the plunger,
that causes the change. LS Visual
atrium
ventricle
vena cava
aorta
coronary artery
sinoatrial node
blood pressure
pulse
heart attack
stroke
Figure 8 Simplified diagram mapping
The pulmonary circuit transports blood between the heart and lungs; the
systemic circuit transports blood between the heart and the rest of the body.
Lung
capillaries
Pulmonary
artery
Pulmonary
circulation
Pulmonary
vein
Veins
Valves
Systemic
circulation
Arteries
Capillaries
Oxygen-poor blood
Oxygen-rich blood
880
TAKS 1 Bio/IPC 2A; TAKS 2 Bio 10A
Chapter Resource File
pp. 880–881
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B, 11C
Teacher Edition
TAKS Obj 1 Bio/IPC 2A
TAKS Obj 2 Bio 10A, 10B
TEKS Bio 5A, 10A, 10B, 11C
TEKS Bio/IPC 2A
880
• Lesson Plan GENERAL
• Directed Reading
• Problem Solving GENERAL
Transparencies
TT
TT
TT
TT
Bellringer
Circulatory Loops in the Human Body
Path of Bloodflow Through the Heart
Electrical Regulation of the Heart
Chapter 38 • Circulatory and Respiratory System
Planner CD-ROM
• Reading Organizers
• Reading Strategies
• Problem Solving Worksheet
Computing Rates and Heart
Efficiency GENERAL
Circulation of Blood
As shown in Figure 9, the heart has a wall that divides the right and
left sides of the heart. At the top of the heart are the left and right
atria (AY tree uh). The atria (singular, atrium), are chambers that
receive blood returning to the heart. Below the atria are the left and
right ventricles, thick-walled chambers that pump blood away
from the heart. A series of one-way valves in the heart prevent blood
from moving backward. Figure 9 summarizes the path blood
follows through the heart:
Two large veins called the inferior vena cava and superior vena
cava collect all of the oxygen-poor blood from the body. The
venae cavae empty blood directly into the right atrium of the
heart.
Interpreting Graphics
In human anatomy, the
terms left and right always
refer to the left and right
from the perspective of the
subject. This will help you
understand why the terms
left and right appear
reversed in anatomical
drawings, such as that
of the heart in Figures 8
and 9.
The blood from the right atrium moves into the right ventricle.
As the right ventricle contracts, it sends the blood into the pulmonary arteries.
The pulmonary arteries carry the blood to the right and left
lungs. At the capillaries of the lungs, oxygen is picked up and
carbon dioxide is unloaded.
The freshly oxygenated blood returns from the lungs to the left
side of the heart through the pulmonary veins, which empty the
blood directly into the left atrium.
From the left atrium, the blood is pumped into the left ventricle.
Figure 9 Blood flow through the heart
The arrows trace the path of blood as it travels through the heart.
Teach
Teaching Tip
Nourishing the Heart Point out
to students that the heart cannot get
nutrients and oxygen from the blood
in its own chambers. This is because
the heart muscle is too thick for diffusion to be an effective means of
distribution. Instead, the heart must
rely on the coronary arteries to
sustain it. These two arteries lie in
grooves that spiral around the heart.
An obstruction in one of their
branches often necessitates bypass
surgery to restore proper blood flow
to the heart. Restricted blood flow
can result in angina pectoris, which
is chest pain, or a myocardial infarction, which is a heart attack. Heart
cells die during an infarction, which
limits the heart’s pumping
efficiency.
TAKS 2 Bio 10A, 10B (grade 11 only)
Superior vena cava
sends O2-poor blood
from upper body to
right atrium.
Aorta sends blood to the coronary
arteries, the brain, and the rest of
the body.
Using the Figure
Pulmonary arteries
Have students examine Figure 9.
Have them use their fingers to trace
the path that blood follows through
the heart. Tell students that although
the heartbeat is described for convenience as occurring first on the
right side and then on the left, the
movement of blood occurs on both
sides simultaneously. Have students
compare the sizes of the left and
right ventricle walls. Ask why the
left ventricle wall is thicker than the
right. (Blood is pumped to the entire
body from the left ventricle. Blood
from the right ventricle goes only as
far as the lungs.) LS Visual
send blood to the lungs.
Right lung
Left lung
Pulmonary veins
Right atrium
sends blood to the
right ventricle.
return blood to the
left atrium from
the lungs.
Right ventricle
Left atrium
sends blood to the
pulmonary artery.
sends blood to the
left ventricle.
Inferior vena cava
Left ventricle
sends O2-poor blood
from lower body to
right atrium.
sends blood to
the aorta.
Blood from aorta to body
TAKS 1 Bio/IPC 2A
881
Demonstration
REAL WORLD
CONNECTION
Aerobic exercise conditions the heart and
lungs by increasing the oxygen available to
the body and by enabling the heart to use
oxygen more efficiently. During dynamic
aerobic exercise, such as walking, tennis,
soccer, and volleyball, the cardiorespiratory
system responds by increasing oxygen supply
to the muscles. This occurs as a result of the
nervous system increasing cardiac output and
reducing vascular resistance in small blood
vessels. Cardiac output (the amount of blood
pumped with each heart beat) is increased by
increasing the heart rate and/or by increasing
the strength of the heart beat. The reduction
in vascular resistance results in higher levels
of oxygen being delivered to body tissues.
A conditioned athlete’s resting heart rate is
lower than that of an unconditioned person.
The athlete’s cardiac output is also greater
than an unconditioned person’s. Going
from the resting to maximal exercise states,
oxygen consumption increases by 10 times
in untrained people and by 20 to 30 times in
conditioned athletes. TAKS 2 Bio 10A; Bio 11C
GENERAL
Show students a transparency
containing a diagram of a fish’s cardiovascular system. Point out that
the fish’s cardiovascular system has
only one circuit in it, rather than the
two circuits found in mammals.
Trace the pathway of blood from
the heart, over the gills, to body
tissues, and back to the heart. Ask
students why the number of cardiovascular system circuits of fish and
mammals might be different. (Fish
are ectothermic animals that have
lower metabolic demands than mammals; therefore, their needs for oxygen
are also lower.) TAKS 1 Bio/IPC 2A
Chapter 38 • Circulatory and Respiratory Systems
881
Teach, continued
continued
Teaching Tip
The Intrinsic Heartbeat Point
out to students that cardiac muscle
cells have an intrinsic, or selfinitiated, beat. Contractions of the
heart muscle are not produced by
stimulation from nerves. Nerves
control only the rate of the heart’s
contractions. In addition, cardiac
muscle cells influence each other.
The sinoatrial node and the atrioventricular node (which stimulates
the ventricles to contract) trigger
contractions of the other heart
muscle cells in the same chamber.
Thus, contraction of the cells of the
atria and then of the ventricles is
synchronized.
Figure 10 Electrical
regulation of the heart. The
SA node, or pacemaker, fires
ahead of each heart contraction. The wave of contraction
spreads across both atria and
delays for an instant before it
travels to the ventricles.
Sinoatrial
(SA) node
Student Edition
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 10A, 10B
Teacher Edition
TAKS Obj 2 Bio 10A
TEKS Bio 5A, 11A, 11B, 11C
TEKS Bio/IPC 3C
882
The first arteries to branch from the aorta are the coronary
(KOHR uh neh ree) arteries , which carry freshly oxygenated blood
to the heart muscle. Other arteries also branch from the aorta and
carry oxygen-rich blood to all parts of the body.
After delivering oxygen to the cells of the body and picking up
carbon dioxide, the cycle continues when blood returns to the heart
through the inferior or superior venae cavae.
Contraction of the heart is initiated by a small cluster of cardiac muscle cells called the sinoatrial (SIE noh ay tree uhl) node, which is
embedded in the upper wall of the right atrium. The cells that make
up the sinoatrial node (SA node, for short) act as the pacemaker of
the heart. These cells “fire” an electrical stimulus in a regular
rhythm. Each stimulus is followed immediately by a contraction that
travels quickly in a wave and causes both atria to contract almost
simultaneously, as shown in Figure 10.
The wave of contraction spreads from the atria to the ventricles,
but almost one-tenth of a second passes before the ventricles start
to contract. The delay permits the atria to finish emptying blood
into the ventricles before the ventricles contract simultaneously.
The wave of contraction is conducted rapidly over both ventricles
by a network of nerve fibers in the heart.
On average, heart contractions occur at a rate of about 72 times
per minute. During sleep the rate decreases, and during exercise it
increases. The SA node is controlled by two sets of nerves with
antagonistic (opposite) signals and is influenced by many factors,
including hormones, temperature, and exercise.
Demonstration
pp. 882–883
The blood then enters one of the largest arteries of the body, the
aorta (ay OHR tuh).
Initiating Contraction
TAKS 2 Bio 10A; Bio 5A, 11A
Invite the school nurse to demonstrate how a stethoscope can be
used to hear the sounds of a heartbeat. Tell students that the “lubb”
and “dup” sounds that are heard
are made when the valves of the
heart close. Explain that the valves
of the heart open with each contraction and let blood through to
the next chamber or to an artery.
The valves then close to stop blood
from moving backward. In this
way, the valves keep blood moving
through the heart and out to the
body. Valve disease occurs when a
valve doesn’t work the way it
should. If a valve doesn’t open all
the way, less blood can move
through the smaller opening. If a
valve doesn’t close tightly, blood
may leak backward. A heart murmur is an abnormal sound that can
be heard when listening to a person’s heartbeat. TAKS 2 Bio 10A
After a slight delay that permits the left atrium to empty completely, the left ventricle contracts. The walls of the left ventricle
are muscular, so the left ventricle’s contraction is forceful.
Monitoring the Cardiovascular System
Heart disease is one of the leading causes of death among people in
the United States. Health professionals use several different methods to monitor the health of the circulatory system.
Blood pressure Doctors routinely measure patients’ blood pressure.
Blood pressure is the force exerted by blood as it moves through
Figure 11 Monitoring
blood pressure. Blood
pressure is measured with
a blood pressure cuff, a
stethoscope, and a mercury
(Hg) column gauge.
blood vessels. Blood pressure readings provide information about
the conditions of the arteries.
Blood pressure is measured with a blood pressure cuff and gauge,
shown in Figure 11. Blood pressure is expressed in terms of millimeters of mercury (mm Hg) and is usually reported as the systolic
pressure written over the diastolic pressure. The first number, the
systolic pressure, is the pressure exerted when the heart contracts
and blood flows through the arteries. The diastolic pressure is the
pressure exerted when the heart relaxes.
882
TECHNOLOGY
CONNECTION
When the heart’s rhythm is disrupted causing
the heartbeat to be too fast, too slow, or
irregular, an artificial pacemaker may become
necessary. These disruptions may be caused by
a blockage in the electrical pathway that regulates heart rhythm, or by some other defect in
the heart’s natural pacemaker. An artificial
pacemaker is a small, battery-operated device
Chapter 38 • Circulatory and Respiratory Systems
that helps the heart beat in a regular rhythm.
Some pacemakers are permanently implanted
in the chest wall, and some are worn externally. The pacemaker sends electrical impulses
to the heart, which helps to regulate the
heart’s rhythm. An electrode is placed next to
the heart wall and small electrical charges
travel through the wire to the heart.
TAKS 2 Bio 10A; Bio/IPC 3C
Normal blood pressure values are from 100 to 130 for systolic
pressure and from 70 to 90 for diastolic pressure. An example of a
normal reading would be written 120/80 mm Hg. These figures
indicate the blood is pushing against the artery walls with a pressure of 120 mm Hg as the heart contracts and 80 mm Hg as the
heart rests.
Many Americans suffer from a condition called high blood pressure, or hypertension. High blood pressure places a strain on the
walls of the arteries and increases the chance that a vessel will burst.
Left untreated, hypertension can lead to heart damage, brain damage, or kidney failure. Regular aerobic activity can help people to
maintain a healthy blood pressure. Hypertension can be easily diagnosed and usually can be controlled by medicine, diet, and exercise.
The Greek word for heart is
kardia. Because of the k in
this word, electrocardiogram
is sometimes abbreviated as
EKG instead of ECG.
Electrocardiograms (ECGs or EKGs) A common way to monitor the
heart’s function is to measure the tiny electrical impulses produced
by the heart muscle when it contracts. Because the human body is
composed mostly of water with dissolved ions, it conducts electrical
currents. A small portion of the heart’s electrical activity reaches the
body surface. As shown in Figure 12, an instrument called an electrocardiograph uses special sensors to detect the electrical activity. A
recording of these electrical impulses is called an electrocardiogram,
abbreviated as ECG or EKG. In one normal heartbeat, three successive electrical-impulse waves are recorded, as shown in Figure 12.
Heart Rate It takes only a watch with a second hand to measure
your pulse. Your pulse is a series of pressure waves within an artery
caused by the contractions of the left ventricle. A person’s pulse is
an indicator of his or her heart rate—how fast or slow the heart is
beating. Each time the blood surges from the aorta, the elastic walls
in the blood vessels expand and stretch. This rhythmical expansion
can be felt as a pulse in areas where the vessel nears the surface of
the skin. The number of pulses counted per minute represents the
number of heartbeats per minute. The most common site for taking
a pulse is at a radial artery, on the thumb side of each wrist. The
average pulse rate ranges from 70 to 90 beats per minute for adults.
Teaching Tip
Heart Attacks Tell students that
hypertension, or high blood pressure, is a serious health condition
because it is the major cause of
heart failure, kidney failure, and
stroke. Ask students to use outside
sources to research hypertension
and prepare a report that explains
the causes of this condition, how it
can be prevented or treated, and
the incidence of hypertension in the
United States compared with that
of other countries. Bio 11B, 11C
Group Activity
Figure 12 Monitoring
heart contractions. The
electrical changes with each
heart contraction can be
detected with an electrocardiograph. The characteristic
up-and-down waves are
analyzed to assess the health
of the heart.
GENERAL
Measuring Blood Pressure Have
the school nurse demonstrate how
a sphygmomanometer works.
Remind students that blood pressure readings include two numbers,
the systolic and diastolic pressures,
represented as a ratio. The systolic
reading, the first value, is the pressure on the artery walls exerted by
the contracting ventricles. The diastolic reading, the second value, is
the pressure on the blood vessel
walls during ventricular relaxation.
Electrocardiogram
Atria contract
Ventricles relax
TAKS 2 Bio 10A
Teaching Strategies
Bring in a sheep heart or a
picture of a human heart and
point out the coronary arteries
to students.
Ventricles contract
883
Obesity Health problems resulting from
overweight and obesity could reverse many
of the health gains achieved in the U.S. in
recent decades, according to a Surgeon
General’s “call to action” issued in
December of 2001. “Overweight and obesity may soon cause as much preventable
disease and death as cigarette smoking,”
then Surgeon General David Satcher said.
Being overweight is a risk factor for heart
disease, high blood pressure, diabetes, some
cancers, asthma, and other conditions.
What Is a Heart Attack?
Approximately 300,000 U.S. deaths a year
currently are associated with obesity and overweight (compared to more than 400,000 deaths
a year associated with cigarette smoking). The
total direct and indirect costs attributed to
overweight and obesity amounted to $117
billion in the year 2000. In 1999, an estimated
61 percent of U.S. adults were overweight,
along with 13 percent of children and adolescents. Obesity among adults has doubled since
1980, while the number of overweight adolescents has tripled. TAKS 2 Bio 10A; Bio 11C
Discussion
• Identify the ways arteries
become blocked. (blood clots,
atherosclerosis, arteriosclerosis)
• Why do doctors recommend
that certain people take an
aspirin a day? (Aspirin acts as
an anticoagulant, keeping the
blood flowing.)
• How can aspirin help prevent
heart attacks? (Thinner blood
is less likely to clot, but it will
not prevent plaques from coming loose or other causes for
heart attacks.)
Transparencies
TT Electrocardiogram
TT Electric Regulation of the Heart
Chapter 38 • Circulatory and Respiratory Systems
883
Diseases of the blood vessels serving the heart and brain are leading causes of premature death and disability in the United States.
When either the heart or the brain does not get enough blood, parts
of the organ die. A heart attack occurs when an area of the heart
muscle stops working and dies. When an area of the brain dies the
result is a stroke. Death or varying degrees of disability may result.
Factors that contribute to heart attacks and strokes are cigarette
smoking, lack of physical activity, diets high in saturated fats, and
unmanaged stress.
Close
Reteaching
Review the Demonstration on the
first page of this section. Have
students infer which blood vessel
would have the highest blood pressure. (the aorta, as blood is leaving
the left ventricle) Which blood
vessel would have the lowest blood
pressure? (the vena cava, as blood is
returning to the right atrium) Have
them justify their choices.
LS Logical TAKS 2 Bio 10A; Bio 3E
Quiz
GENERAL
1. Blood leaving the heart through
the pulmonary artery goes to
________ . (the lungs)
2. How is a heartbeat stimulated?
(by electrical stimuli from the
sinoatrial (SA) node in the right
atrium that stimulates other heart
cells to contract)
3. What is an EKG? (electrocardiogram, a record of the electrical
activity of the heart)
4. What is a heart attack? (death of
an area of the heart that has had
its blood supply cut off)
Cholesterol
crystals
Exploring Further
TAKS 2
What Is a Heart Attack?
You may feel a sharp, crushing, squeezing pain in
your chest. You may have mild pain in your jaws
or down an arm. You may break into a cold sweat
and feel nauseated. Some of these symptoms
occur in almost 2 million Americans each year
when they experience a heart attack. Some
people experience almost no symptoms.
Why Do Heart Attacks Occur?
Heart attacks usually happen when the arteries
that deliver oxygen to the heart, the coronary
arteries, become blocked. Heart cells begin to
die very quickly without blood. If a large part of
the heart is affected, the victim can die immediately or within a few days or weeks.
Blockage of Arteries
A blood clot formed somewhere else in the body
can break loose and flow to the heart or to the
brain, where it blocks the flow of blood. Blood
flow is also blocked by the buildup of fatty
deposits, including cholesterol, a condition called
atherosclerosis (ath uhr oh skluh ROH sihs).
Fat
Normal artery
Artery with fatty deposits
When calcium is deposited in the fatty buildup,
the condition is called arteriosclerosis (ahr tihr ee
oh skluh ROH sihs), or hardening of the arteries.
Hardened arteries cannot expand to handle the
volume of blood that enters every time the heart
contracts. Pressure builds up in the artery and
causes the heart to work harder.
Prevention
High blood pressure, high cholesterol levels, and
cigarette smoking are all controllable risk factors
in heart disease. Not smoking at all, early diagnosis and treatment of high blood pressure, regular
medical checkups, a healthy diet, and regular
exercise can all help prevent a heart attack or
decrease the severity of one.
TAKS 2 Bio 10A; Bio 11A, 11B
Section 2 Review
Alternative
Assessment
GENERAL
Summarize the path of blood through the body
Identify three ways that the condition of the
starting and ending with blood that has just
10A
returned from the lungs to the heart.
cardiovascular system can be monitored.
Have students design a crossword
puzzle using key vocabulary words
for the heart and circulation.
List the sequence of events that results in atrial
LS Verbal TAKS 2 Bio 10A
and ventricular contraction.
10A
Describe the function of the SA node.
10A
10A
Differentiate between a heart attack and a
stroke.
10A 10B 11C
TAKS Test Prep When the right ventricle
10A
contracts, it pumps blood to the
A lungs.
C right atrium.
B aorta.
D rest of the body.
884
Answers to Section Review
pp. 884–885
Student Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B, 11C
Teacher Edition
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TEKS Bio 3E, 4B, 10A, 11A, 11B,
11C
884
1. left atrium, left ventricle, aorta, arteries, capillaries, veins, vena cava, right atrium, right
ventricle, pulmonary arteries, lungs, and pulmonary veins TAKS 2 Bio 10A
2. When the sinoatrial node is activated, it causes
the atria to contract. After about a one-tenth of
a second pause, the ventricles contract.
TAKS 2 Bio 10A
3. The SA node acts as a heart pacemaker by providing an electrical stimulation that regulates
the heart’s rhythm. TAKS 2 Bio 10A
4. EKG, blood pressure, and pulse can be used to
monitor cardiovascular system condition.
TAKS 2 Bio 10A
Chapter 38 • Circulatory and Respiratory Systems
5. A heart attack occurs when a blood vessel in
the heart becomes blocked. A stroke occurs
when a blood vessel in the brain becomes
blocked. TAKS 2 Bio 10A, 10B; Bio 11C
6.
A. Correct. Blood moves from
the right ventricle to the lungs for oxygenation,
then back to the heart. B. Incorrect. Blood from
the left ventricle enters the aorta. C. Incorrect.
Blood moves from the right atrium to the right
ventricle. D. Incorrect. Blood leaving the left
ventricle moves to the rest of the body except
the lungs. TAKS 2 Bio 10A
The Respiratory System
Section 3
Section 3
Focus
Gas Exchange
Objectives
A person can go without water for a few days and without food for
more than a week. But if a person stops breathing for more than a
few minutes, he or she will die. Breathing is the means by which
your body obtains and releases gases. Oxygen is used by your cells
to completely oxidize glucose and then make ATP, the main energy
currency in your cells. Without oxygen, your body cannot obtain
enough energy from food to survive. Excess carbon dioxide produced as a waste product of aerobic respiration is toxic to cells and
must be removed.
The Path of Air
Breathing is only one part of gas exchange. The gases must be
transported by the cardiovascular system and then exchanged at
the cells. All of the organs and tissues that function in this exchange
of gases make up the respiratory system, as shown in Figure 13.
A breath of air enters the respiratory system through the nose or
mouth. Air is made up of many gases. About 21 percent of air is
oxygen gas. Hairs in your nose filter dust and particles out of the
air. Tissues that line the nasal cavity moisten and warm the air.
Overview
● Summarize the path that
air follows when it enters
the body through the nose
or mouth.
10A TAKS 2
● Describe the role of the rib
muscles and diaphragm in
breathing.
10A TAKS 2
● Describe how breathing
rate is regulated.
10A TAKS 2
● Summarize how oxygen
and carbon dioxide are
transported in the blood.
● Identify three serious
diseases of the lungs.
Key Terms
pharynx
larynx
trachea
bronchus
alveolus
diaphragm
Before beginning this section
review with your students the
objectives listed in the Student
Edition. Students will sequence the
structures through which air passes
as it enters and exits the body. They
will describe the mechanism of
breathing and how it is regulated.
They will also explain how oxygen
is transported in the blood, how it
is exchanged with carbon dioxide
in body tissues, and how carbon
dioxide is transported in the blood.
Finally, students will develop an
appreciation for the symptoms of
and treatments for several respiratory diseases.
Bellringer
Ask students to write a sentence or
two describing why their breathing
rate would increase from exercise or
fright. (In either case, the respiratory
center in the brain would stimulate
the muscles involved in breathing to
increase their rate of contraction and
prepare the body to meet either actual
or potential oxygen needs.) Bio 11B
Respiratory System
Capillaries
Pharynx
Larynx
Trachea
Left lung
Right lung
Motivate
Discussion/
Question
Bronchi
Bronchioles
Alveoli
Diaphragm
Figure 13 Taking in and
exchanging gases. The
respiratory passages, lungs,
and thoracic cavity make up
the respiratory system.
885
Chapter Resource File
• Lesson Plan GENERAL
• Directed Reading
• Active Reading GENERAL
• Data Sheet for Math Lab
• Data Sheet for Quick Lab
GENERAL
GENERAL
Transparencies
TT Bellringer
TT The Human Respiratory System
Planner CD-ROM
• Reading Organizers
• Reading Strategies
• Supplemental Reading Guide
Microbe Hunters
• Occupational Application Worksheet
Respiratory Therapist GENERAL
GENERAL
Point out that air pressure affects
respiration in humans. Gases are
exchanged between the air in the
alveoli and the blood in the capillaries entirely by diffusion. Have
students postulate why a person
breathes deeper and faster at higher
altitudes, where there is decreased
pressure. (At high altitudes, hemoglobin’s affinity for oxygen is lower.
At 6,000 m [9,000 ft], the oxygen
saturation of hemoglobin is only 67
percent, compared to 98 percent at
sea level. One must become acclimated over time to the low levels of
oxygen.) Athletes who train at high
altitudes tend to perform better in
lower altitudes than those who
train in low altitudes. LS Logical
TAKS 2 Bio 4B; Bio 11A, 11B
Chapter 38 • Circulatory and Respiratory Systems
885
Real Life
The lungs of human
fetuses do not function
until birth.
A fetus’s
umbilical
cord contains
blood vessels
that lead to
and from the
placenta,
which contains fetal
and maternal
capillaries. The O2 in
the mother’s capillaries
diffuses to the fetus’s
capillaries, and the CO2
in the fetus’s capillaries
diffuses into the mother’s
capillaries.
Finding Information
Determine the signal that
stimulates the baby to start
11A
breathing at birth.
Teach
Teaching Tip
Larynx Point out to students
where the vocal cords—larynx—
are found. Explain that sound is
produced when air is forced through
the larynx. Also inform students
that laryngitis is simply an inflammation of the vocal cords in which
they lose their ability to vibrate.
Hence, people “lose their voice.”
TAKS 2 Bio 10A
76
18
0
2
x 2+ 6x
5
-7-0
<
493
Calculating the
Amount of Air
Respired
Skills Acquired
Analyzing data, calculating, inferring relationships
8
493
1. 15 breaths/min 0.5 L/breath
7.5 L/min
2. 7.5 L/min 60 min/hr 450 L/hr
3. Answers will vary but may
include that infants have
smaller lungs, a faster heart
rate, and a faster metabolism.
x 2+ 6x
TT Inhalation and Exhalation
0
2
5
-7-0
<
Answers to Analysis
Transparencies
Lungs
The lungs, which are among the largest organs in the body, are suspended in the chest cavity, bounded on the sides by the ribs and on
the bottom by the diaphragm (DIE uh fram). The diaphragm is a
powerful muscle spanning the rib cage under the lungs, and it aids
in respiration. A double membrane surrounds both lungs. The outermost membrane is attached to the wall of the thoracic cavity, and the
inner membrane is attached to the surface of the lungs. Between
both membranes is a small space filled with fluid.
TAKS 1 Bio/IPC 2C, 2D
Teacher’s Notes
Ensure that students understand
that units are important in
dimensional analysis.
From the nose, air passes through a muscular tube in the upper
throat called the pharynx (FAIR ingks), which serves as a passageway for air and food. The air continues on through a passageway
for air, called the larynx (LAIR ingks), or voice box located in the
neck. A flap of tissue, the epiglottis (ehp uh GLAHT ihs), covers the
opening to the larynx when you swallow food and liquids. This prevents food and liquids from passing into your lungs.
From the larynx the air passes into the trachea (TRAY kee uh), a
long, straight tube in the chest cavity. The trachea, or windpipe,
divides into two smaller tubes, the bronchi (BRAHNG kie), which
lead to the lungs. Within the lung, the bronchi (singular, bronchus)
divide into smaller and smaller tubes called bronchioles (BRAHNG
kee ohls). The smallest bronchioles end in clusters of air sacs called
alveoli (al VEE uh lie), where gases are actually exchanged. As
shown in Figure 13, each of the 300 million small alveoli is surrounded by a jacket of capillaries. Alveoli increase the surface area
of your lungs to as much as 42 times the surface area of your body.
The cells that line the bronchi and trachea secrete mucus that traps
foreign particles in the air. The mucus is directed upward by cilia to
the epiglottis, where the mucus is swallowed and digested. Microbes
in the mucus are destroyed by acids and enzymes in the stomach.
Calculating the Amount
of Air Respired 2C 2D TAKS 1
Background
Most adults take in about 0.5 L of air with each
breath. The normal breathing rate is about 8 to 15
breaths per minute.
Analysis
1. Calculate the volume of air
in liters an adult breathes per
minute if his or her breathing
rate is 15 breaths per minute.
2. Calculate the volume of air
in liters an adult breathes per
hour if his or her breathing
rate is 15 breaths per minute.
MATH TAKS Obj 9, 8.3; Obj 10, 8.14A, C, 8.16A
3. Critical Thinking
Inferring Conclusions The
breathing rate of an infant is
about 40 breaths per minute.
Why might infants have higher
respiratory rates than adults?
886
INCLUSION
pp. 886–887
Student Edition
TAKS Obj 1 Bio/IPC 2C, 2D
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B
TEKS Bio/IPC 2C, 2D
Teacher Edition
TAKS Obj 1 Bio/IPC 2C, 2D
TAKS Obj 2 Bio 10A, 10B
TEKS Bio 3D, 3E, 10A, 10B, 11C, 11D
TEKS Bio/IPC 2C, 2D
Newborns In addition to using lungs for the
first time, a newborn’s heart and cardiovascular system change with the first breath. An
opening, the foramen ovale, lies between the
left and right atria. Another structure, the ductus arteriosus, connects the pulmonary artery
to the aorta. Upon inspiration for the first
time, the lungs are inflated, closing the opening
and separating pulmonary circulation from the
systemic circulation.
TAKS 2 Bio 10B (grade 11 only)
Strategies
• Attention Deficit Disorder • Learning Disabilities
Have students determine the average breathing rate for students in their class. The
students should record how many breaths
(inhale and exhale equals one breath) each
student takes for one minute. Have students
add each rate and divide by the number of
students included in the test to figure the
average breathing rate. Additionally, students
may recruit adult volunteers and determine
their breath rates and compare the results
with those taken in class.
TAKS 1 Bio/IPC 2C;TAKS 2 Bio 10A
886
Chapter 38 • Circulatory and Respiratory System
Breathing
Air is drawn into and pushed out of the lungs by the mechanical
process known as breathing. Breathing occurs because of air pressure differences between the lungs and the atmosphere, as shown in
Figure 14. To draw air into the lungs, a process called inhalation, the
rib muscles contract. This draws the rib cage up and out, and the
diaphragm contracts, moving downward. The volume of the chest
cavity increases, which reduces the air pressure within the cavity
below the atmospheric pressure. Because air flows from a high pressure area to a low pressure area, air is drawn into the lungs.
Normal exhalation (breathing out) is a passive process. The rib
cage and diaphragm muscles relax, which returns the rib cage and
diaphragm to their resting position. The relaxation of these muscles
decreases the volume in the chest cavity and increases the air pressure in the lungs. Because the air pressure is now higher in the
lungs than in the atmosphere, air is forced out—from a high pressure area to a low pressure area.
Teaching Tip
Spirometer Patients in hospitals
are at risk for lung infections
because they are inactive. If a patient
is bedridden, he or she must breathe
deeply to get air deep into the lungs
and help prevent fluids from accumulating there. Inhaled bacteria can
grow easily in warm, moist air and
patients can develop pneumonia.
Hospital staff check a patient’s tidal
volume several times a day with a
spirometer to ensure enough air is
being expelled and inhaled. Bio 11C, 11D
Breathing Rate
You took your first breath within moments of being born. Since then,
you have repeated the process more than 200 million times. What
controls how fast or slow you breathe? Receptors in the brain and cardiovascular system continually monitor the levels of oxygen and
carbon dioxide in the blood. The receptors enable the body to
automatically regulate oxygen and carbon dioxide concentrations by
sending nerve signals to the brain. The brain responds by sending
nerve signals to the diaphragm and rib
Figure 14 Inhalation and exhalation
muscles in order to speed or slow the rate
The
diaphragm and the muscles between the ribs are involved
of breathing.
in the movement of the chest cavity during breathing.
It may surprise you to know that
carbon dioxide levels have a greater
Inhalation
Exhalation
effect on breathing than do oxygen levels. For example, if the concentration of
carbon dioxide in your blood increases,
such as during exercise, you respond by
breathing more deeply, ridding your
body of excess carbon dioxide. When the
Lung
carbon dioxide level drops, your breathRib
ing slows. Factors such as stress, pain,
and fear also influence breathing rate.
Rib cage
The signals that travel from the
muscles
breathing center of the brain are not
subject to voluntary control. You cannot
Diaphragm
simply decide to stop breathing indefinitely. You can hold your breath for a
while, but even if you lose consciousness
When the diaphragm contracts,
When the diaphragm
your respiratory control center will take
it moves down and air rushes in.
relaxes, it moves up
and air is forced out.
over and force your body to breathe.
887
Career
Anesthesiologists Anesthesiologists (anesthetists) are physicians who complete a fouryear college program, four years of graduate
medical training and four more years of anesthesiology residency. Their primary role in the
operating room is to ensure the patient’s comfort during surgery and also to make informed
medical judgments to protect the patient. These
include treating and regulating changes in critical life functions, including breathing, heart
rate, and blood pressure. These specialists
immediately diagnose and treat any medical
problems that might arise during surgery
or recovery.
Anesthesiologists also work in intensive care
units to help restore critically ill patients to
stable condition. Anesthesiologists are involved
in pain management, including diagnosis and
treatment of acute and chronic problems.
The field of anesthesiology is growing and
opportunities for employment are excellent.
Starting salary will vary by subspecialty
and region. Bio 3D
READING
SKILL
BUILDER
Brainstorming Lead a class discussion on the mechanism of breathing.
Ask for volunteers to describe the
locations of the muscles involved
in breathing and what happens to
them during inhalation and
exhalation. (A volunteer could draw
sketches similar to those in Figure 14
to illustrate the process.) Ask students
if the walls of the lungs also have
muscles and, if so, are they involved
in breathing. (No.) LS Logical
TAKS 2 Bio 10A
Demonstration
Demonstrate how breathing works
by making a model of the lungs
and diaphragm. You will need a
bell jar, one small balloon, a glass
tube, a one-holed rubber stopper, a
thin rubber sheet, and a rubber
band. Attach the deflated balloon
to one end of the short glass tube
that has been inserted through the
one-holed rubber stopper. Use the
stopper to plug the mouth of a bell
jar, allowing the balloon to hang
inside the jar. Use a rubber band to
fasten a thin sheet of rubber over
the mouth of the jar. Pull down on
the rubber sheet, and have students
observe what happens to the balloon. Have students relate their
observations to inhalation. Release
the rubber sheet. Have them relate
their observations to exhalation.
Ask students the drawbacks of this
model. (Chest muscles do not move;
only one lung is shown.) LS Visual
TAKS 2 Bio 10A; Bio 3E
Chapter 38 • Circulatory and Respiratory System
887
Gas Transport
Breathing is the first step to getting oxygen to the trillions of cells
in your body. When oxygen molecules diffuse from the air into your
alveoli, their journey has just begun, as shown in Figure 15. As
oxygen passes into the plasma of the bloodstream, it is picked up
by red blood cells that carry an iron-containing protein called
hemoglobin.
Teach, continued
continued
READING
SKILL
BUILDER
Reading Organizer Encourage
students to keep a vocabulary notebook, a stack of vocabulary cards,
or some other way of recording
and reviewing unfamiliar vocabulary. Each entry should include not
only the correct spelling of the
word but also a definition, preferably one in the student’s own
words. This strategy will be especially beneficial in a chapter like
this one, where students encounter
many new terms. LS Visual
Oxygen Transport
Each hemoglobin molecule contains four atoms of iron. The iron
atoms in the hemoglobin give red blood cells their red color. The
iron atoms bind reversibly with oxygen. Reversible binding means
that at the appropriate time, the oxygen can be released elsewhere
in the body and be taken up by the cells that need it.
Figure 15 summarizes the path of oxygen and carbon dioxide
through the body:
Figure 15 O2 and CO2
transport in the blood.
Hemoglobin molecules inside
red blood cells transport
oxygen, while most carbon
dioxide is transported as bicarbonate ions in the plasma.
Oxygen from the outside air reaches the lungs.
The oxygen diffuses from the alveoli to the pulmonary capillaries. At the high oxygen levels that occur in the blood within the
lungs, most hemoglobin molecules carry a full load of oxygen.
CO2 is exhaled.
Demonstration
O2 is inhaled.
CO2
Have a volunteer gently blow
through a straw into a beaker that
contains a weak solution of bromothymol blue (BTB) and water.
The color will change slowly to
green then yellow, indicating the
presence of CO2. Actually, BTB is
an indicator of acid. The bicarbonate ions and carbonic acid created
by blowing air into the indicator
mixture lower the pH of the indicator mixture which leads to the
color change. LS Visual
TAKS 4 IPC 9B (grade 11 only)
O2
Alveoli
CO2 is released
in its gaseous
form to the
alveoli.
CO2
O2
CO2
Pulmonary
arteries
Pulmonary
vein
O2
O2 diffuses
into blood.
HCO3–
HCO3–
Most CO2
travels in the
blood as
bicarbonate
ions (HCO3– ).
Red blood cells
carry O2.
HCO3–
O2
Heart
Systemic
veins
Systemic
arteries
CO2
Transparencies
O2
O2
CO2 diffuses to the blood.
TT O2 and CO2 in the Blood
O2 diffuses into cells.
CO2 O2
Cells
The oxygen-rich blood then
travels to the heart. The heart
pumps the blood to the tissues of the body.
Oxygen diffuses into the cells
for use during aerobic respiration. In the tissues, oxygen
levels are lower. This causes
the hemoglobin to release its
oxygen.
In tissues, the presence of
carbon dioxide produced by
cellular respiration makes the
blood more acidic and causes
the hemoglobin molecules to
assume a different shape, one
that gives up oxygen more easily. The carbon dioxide diffuses
from the cells to the blood.
Most of the carbon dioxide
travels to the heart as bicarbonate (HCO3–) ions.
The heart pumps the blood to
the lungs. In the lungs, carbon
dioxide is released in its
gaseous form to the alveoli.
The carbon dioxide is expelled.
888
Cultural
pp. 888–889
Student Edition
TAKS Obj 1 Bio/IPC 2A, 2B, 2C
TAKS Obj 2 Bio 4B
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 4B, 10A, 10B, 11A
TEKS Bio/IPC 2A, 2B, 2C
Teacher Edition
TAKS Obj 1 Bio/IPC 2A, 2B, C
TAKS Obj 2 Bio 10B
TAKS Obj 4 IPC 7D, 8A, 9B
TEKS Bio 10B, 11A, 11B, 11C
TEKS Bio/IPC 2A, 2B, 2C, 3C
TEKS IPC 7C, 7D, 9B
888
Awareness
GENERAL
Saving Lives In 1914, Barrett A. Morgan,
an African American, invented the world’s
first gas mask. Called by many names—
breathing device, safety hood, gas inhalator
—this clever invention won an award at the
Second International Exposition of Safety
and Sanitation in New York in 1914. Two
years later it saved the lives of construction
workers trapped in a smoke-filled tunnel
beneath Lake Erie. Bio/IPC 3C
Chapter 38 • Circulatory and Respiratory System
IPC Benchmark Fact
Have students research the hemoglobin molecule and
determine whether the iron atoms have a valence of
2 or 3 and how these different values affect the
number of oxygen molecules that bind to the iron
atoms. TAKS 4 IPC 7D (grade 11 only)
Carbon Dioxide Transport
At the same time that the red blood cells are unloading oxygen to
tissues, they are also taking in carbon dioxide from the tissues.
Carbon dioxide is carried by the blood in three forms:
Teaching Tip
Respiratory Control Center Tell
students that changes in blood gas
and pH levels trigger changes in the
rate of respiration. Chemoreceptors
in the cartotid arteries (on either
side of the neck) and in the aorta
detect CO2 and O2 concentration
in the blood as well as blood pH.
When these receptors detect high
CO2 levels, low O2 levels, or low
blood pH, they send signals to the
respiratory control center located
in the medulla oblongata of the
brain. In addition, other receptors
that detect high CO2 levels and low
pH in the cerebrospinal fluid of the
brain send signals to the respiratory
control center. When the respiratory control center receives these
signals, it sends signals to the muscles involved in breathing. The
muscles contract more frequently,
which results in an increase in the
respiration rate. This, in turn, lowers CO2 levels, raises O2 levels, and
raises blood pH.
1. About 7 percent of CO2 is dissolved in the blood plasma.
2. About 23 percent of CO2 is attached to hemoglobin molecules
inside red blood cells.
3. The majority of CO2, 70 percent, is carried in the blood as bicarbonate ions.
How is CO2 carried as bicarbonate ions? In the presence of a certain enzyme, carbon dioxide combines with water to form carbonic
acid, H2CO3. This is shown in the equation below. The carbonic acid
then breaks up to form a bicarbonate ion, HCO3–, and a hydrogen
ion, H+:
–
+


H O CO ←

→ H CO ←

→ HCO H
2
2
2
3
3
Thus, most of the CO2 travels in the blood as bicarbonate ions. The
hydrogen ions make the blood more acidic. When the blood reaches
the lungs, the series of reactions is reversed:


HCO – H+ ←

→ H CO ←

→ H O CO
3
2
3
2
2
A bicarbonate ion combines with a hydrogen ion to form carbonic
acid, which in turn forms CO2 and water. The CO2 diffuses out of
the capillaries into the alveoli and is exhaled into the atmosphere.
Modeling the Role of
Bicarbonate in Homeostasis
You can use pH indicator paper, water, and baking soda to
model the role of bicarbonate ions in maintaining blood pH
levels in the presence of carbon dioxide.
2A 2B 2C 11A
TAKS 2 Bio 10B (grade 11 only);
Bio 11A, 11B
TAKS 1
Materials
two 250 mL beakers, 250 mL distilled water, 2.8 g baking soda,
glass stirring rod, 4 strips of wide-range pH paper, 2 drinking straws
Procedure
1. Label one beaker A and
another B. Fill each beaker
halfway with distilled water.
Test and record the pH of the
resulting solution.
5. Repeat step 4 for beaker B.
2. Add 1.4 g of baking soda to
beaker B, and stir well.
Analysis
3. Test and record the pH of the
contents of each beaker.
1. Describe what happened to
the pH in the two beakers
during the experiment.
4. Gently blow through a straw,
into the water in beaker A.
2. State the chemical name for
baking soda.
3. Propose the chemical reaction that might have caused a
change in pH in beaker A.
4. Summarize the effect the
baking soda had on the pH
of the solution in beaker B
after blowing.
TAKS 1 Bio/IPC 2A, 2B, 2C; Bio 11A
Skills Acquired
Inferring, analyzing
Teacher’s Notes
Carefully review the chemical
equations on this page.
5. Critical Thinking
Applying Information
Relate what happened in
beaker B to what occurs in
the bloodstream.
Answers to Analysis
889
ENVIRONMENTAL SCIENCE
CONNECTION
Nearly 335,000 Americans die each year from
lung disease, which is the third leading cause
of death in the United States. During the last
ten years, the death rate for lung disease has
risen faster than that of any of the top five
causes of death.
Air pollution contributes to lung disease,
including respiratory tract infections, asthma,
emphysema, and lung cancer. The major
types of air pollution include excess ozone,
particulate matter, nitrogen dioxide, and sulfur dioxide. Excess ozone in the atmosphere
Modeling the Role
of Bicarbonate in
Homeostasis
results primarily from the action of sunlight
on hydrocarbons and nitrogen oxides emitted
during fuel combustion. Particulate matter air
pollution is a mixture of substances that
includes particles, dust, and aerosols. Principal
sources of nitrogen dioxide are automobiles
and fuel combustion by electric utilities. Sulfur
dioxide is formed when fuel containing sulfur
(mainly coal and oil) is burned. Major sources
of sulfur dioxide are electric utilities and
industrial fuel combustion. Bio 11C
1. A becomes acidic; B becomes
basic.
2. sodium bicarbonate, H2CO33. H2O + CO2
H CO
ᠭᠬ 2 3
4. It buffered the carbonic acid.
5. Most of the CO2 in the blood
travels as bicarbonate ions.
IPC Benchmark
Fact
Remind students that the chemical
change of H2CO3 into HCO3 H (and
vice versa) is an example of an oxidation/reduction reaction, that is, electrons
are shifted from one substance to another. Have advanced students write the
half reactions for this chemical reaction
and identify the substances oxidized and
reduced. TAKS 4 IPC 8A
Chapter 38 • Circulatory and Respiratory System
889
Respiratory Diseases
Respiratory diseases affect millions of Americans. A chronic pulmonary—or lung—disease is one for which there is no cure.
Close
Reteaching
Draw a simplified version of
Figure 15 on the board. Have students close their books, and ask
volunteers to draw arrows showing
the directions of circulation and gas
exchange. Have other volunteers
annotate the diagram with brief
statements that describe key events.
Figure 16 Healthy lungs
and cancerous lungs. The
top photo shows a healthy
lung. The bottom photo
shows a cancerous lung
which contains cells that divide
uncontrollably.
Asthma
Asthma (AZ muh) is a chronic condition in which the bronchioles
of the lungs become inflamed, because of their sensitivity to certain
stimuli in the air. The bronchial walls tighten and extra mucus is
produced, causing the airways to narrow. In severe asthma attacks,
the alveoli may swell enough to rupture. Stressful situations and
strenuous exercise may trigger an asthma attack. Left untreated,
asthma can be deadly. Fortunately, prescribed inhalant medicines
may help to stop an asthma attack by expanding the bronchioles.
People of all ages can have asthma.
LS Visual
Emphysema
TAKS 2 Bio 10B (grade 11 only); Bio 3E
Quiz
Emphysema (ehm fuh SEE muh) is a chronic pulmonary disease
resulting from a chemical imbalance that destroys elastic fibers in
the lungs. Normally, these elastic fibers allow the lungs to expand
and contract. Emphysema begins with the destruction of alveoli. Damage to the alveoli is irreversible and results in constant fatigue and
breathlessness. Severely affected individuals must breathe from tanks
of oxygen in order to live. Smoking is the cause of up to 90 percent of
emphysema cases. Emphysema claims millions of lives annually.
GENERAL
1. The ________ in the lungs are the
sites of oxygen uptake into the
blood. (alveoli)
2. The muscles involved in breathing are the muscles of the
________ and the ________ .
(rib cage, diaphragm)
3. Oxygen is carried in the blood
bound to ________ inside
________ cells. (hemoglobin,
red blood)
4. Carbon dioxide is carried in the
blood primarily in the form of
________ .(bicarbonate ions)
Lung Cancer
Lung cancer is one of the leading causes of death in the world today.
As shown in Figure 16, cancer is a disease characterized by abnormal
cell growth. In the United States alone, about 28 percent—155,000—
of all cancer deaths each year are attributed to lung cancer. Once
cancer is detected, the affected lung is sometimes removed surgically.
Even with such drastic measures, lung cancer usually is not curable.
About 15 percent of lung cancer victims live more than 5 years after
diagnosis.
TAKS 2 Bio 10A, 10B (grade 11 only)
Section 3 Review
Alternative
Assessment
GENERAL
Have students draw pictures of
lungs during inhalation and exhalation. Students should use labeled
arrows to show the direction of
diaphragm and rib muscle movement
and oxygen and carbon dioxide
movement.
Sequence the path a breath of air follows through
Evaluate the role that bicarbonate plays in
transporting carbon dioxide in the blood.
10A 10B
the respiratory system. (Begin with air that enters
10A 10B
through the nose or mouth.)
Critical Thinking Justifying Conclusions
State the direction in which the diaphragm and
rib muscles move before inhalation.
Would a person with emphysema have trouble
10A 10B 11C
climbing stairs? Explain.
10A 10B
TAKS Test Prep
Name the main factor that regulates the rate of
breathing.
Gases are exchanged between
10A
the blood and inhaled air in the
A larynx
C trachea
B alveoli
D bronchi
10A
TAKS 2 Bio 10B (grade 11 only); Bio 3E
890
Answers to Section Review
pp. 890–891
Student Edition
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 10A, 10B, 11C
Teacher Edition
TAKS Obj 2 Bio 10A
TAKS Obj 2 Bio 10B
TEKS Bio 3E, 10A, 10B, 11C
890
1. mouth, trachea, bronchi, bronchioles, and
alveoli TAKS 2 Bio 10A, 10B (grade 11 only)
2. The diaphragm moves down; the ribs move up
and out. TAKS 2 Bio 10A, 10B (grade 11 only)
3. Levels of oxygen and carbon dioxide in the
blood regulate the rate of breathing. Increased
blood carbon dioxide concentration triggers
the brain to send a message to the diaphragm
and rib muscles that speeds up the rate of
breathing. TAKS 2 Bio 10A
4. Seventy percent of the carbon dioxide in the
blood is carried as bicarbonate ions.
TAKS 2 Bio 10A, 10B (grade 11 only)
Chapter 38 • Circulatory and Respiratory System
5. Yes, any physical effort increases the oxygen
needed and energy required to breathe.
TAKS 2 Bio 10A, 10B (grade 11 only); Bio 11C
6.
A. Incorrect. The function of the
larynx is to produce sound. B. Correct. The
alveoli are air sacs where gas exchange takes
place. C. Incorrect. The trachea transports air
to the bronchi. D. Incorrect. The bronchi are
tubes that lead to the lungs. TAKS 2 Bio 10A
Study
CHAPTER HIGHLIGHTS
ZONE
Key Concepts
Alternative
Assessment
Key Terms
Section 1
1 The Circulatory System
●
The human cardiovascular system is made up of blood
vessels, blood, and the heart, which together function to
transport materials, remove wastes, and distribute heat.
●
Arteries carry blood away from the heart. Materials are
exchanged at the capillaries. Veins contain valves and carry
blood back to the heart. Fluids not returned to the capillaries
are picked up by lymphatic vessels.
●
Blood consists of plasma (water, metabolites, wastes, salts,
and proteins), red blood cells, white blood cells, and platelets.
●
Blood types are defined by the presence or absence of
complex carbohydrates on the surface of red blood cells.
cardiovascular system (872)
artery (873)
capillary (873)
vein (873)
valve (874)
lymphatic system (875)
plasma (876)
red blood cell (876)
anemia (877)
white blood cell (877)
platelet (877)
ABO blood group system (878)
Rh factor (879)
GENERAL
Have students make a board game
with questions about normal and
abnormal function of the circulatory and respiratory systems.
TAKS 2 Bio 10B (grade 11 only)
Chapter Resource File
• Science Skills Worksheet GENERAL
• Critical Thinking Worksheet
• Test Prep Pretest GENERAL
• Chapter Test GENERAL
Section 2
2 The Heart
●
The right side of the heart receives oxygen-poor blood from
the body and circulates it to the lungs. In the lungs, gases
are exchanged. The left side of the heart receives oxygenated
blood from the lungs and circulates it to the rest of the body.
●
Atria receive blood entering the heart. Ventricles pump
blood away from the heart.
●
Contraction of the heart is initiated by the sinoatrial node.
The health of the cardiovascular system can be monitored by
measuring blood pressure, electrical impulses, and pulse rate.
●
Blockages in blood vessels can lead to heart attacks or strokes.
3 The Respiratory System
atrium (881)
ventricle (881)
vena cava (881)
aorta (882)
coronary artery (882)
sinoatrial node (882)
blood pressure (882)
pulse (883)
heart attack (884)
stroke (884)
Section 3
●
A series of tubes and bunched air sacs (alveoli) take in
oxygen and remove carbon dioxide.
●
Breathing is caused by pressure changes within the chest cavity.
●
The concentration of carbon dioxide in the blood is the most
critical factor affecting a person’s breathing rate and depth.
●
Oxygen is transported to tissues by combining with hemoglobin molecules inside red blood cells. Most carbon dioxide
is transported to the lungs as bicarbonate ions.
●
Asthma, emphysema, and lung cancer limit lung function.
pharynx (886)
larynx (886)
trachea (886)
bronchus (886)
alveolus (886)
diaphragm (886)
891
Answer to Concept Map
The following is one possible answer
to Performance Zone item 15.
Circulatory system
is composed of
blood vessels
heart
lymphatic system
such as
arteries
capillaries
has
regulates
veins
largest is
largest are
aorta
venae cavae
atria
ventricles
systemic
circulation
pulmonary
circulation
Chapter 38 • Circulatory and Respiratory Systems
891
Performance
ZONE
CHAPTER 38
ANSWERS
Using Key Terms
Using Key Terms
1. The chamber of the heart that sends blood
1. b TAKS 2 Bio 10A, 10B (grade 11 only)
2. b TAKS 2 Bio 10A
3. c TAKS 2 Bio 10A; Bio 11C
4. b TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10A
5. a. Plasma is the liquid part of the
blood; lymph is fluid that
leaks out of blood vessels and
into surrounding tissues.
b. Blood pressure is the pressure
exerted by blood as it moves
through the blood vessels.
Blood pressure is expressed in
mm Hg. Pulse is a series of
pressure waves within an
artery caused by a contraction
of the left ventricle. Pulse is an
indicator of the number of
times the heart beats in a
minute.
c. A heart attack occurs when an
area of the heart muscle is
starved of oxygen and stops
working; it is usually caused
by a blocked blood vessel in
the heart. A stroke is a sudden
attack of weakness or paralysis that occurs when an area of
the brain is starved of oxygen
after blood flow to that part
is interrupted.
Understanding Key Ideas
6. b
7. c
8. a
9. c
10. b
11. c
12. d
TAKS 2
TAKS 2
TAKS 2
TAKS 2
TAKS 2
TAKS 2
TAKS 2
CHAPTER REVIEW
Bio 10A
Bio 10A
Bio 10A
Bio 10A
Bio 10A
Bio 10A, 10B (grade 11 only)
Bio 10A; Bio 11C
to the lungs is the
a. left ventricle.
b. right ventricle.
10A 10B
c. left atrium.
d. right atrium.
2. The pacemaker of the heart is the
10A
a. left ventricle.
c. coronary sinus.
b. sinoatrial node.
d. inferior vena cava.
10A
in the chest cavity decreases during
a. bronchitis.
c. inhalation.
b. exhalation.
d. asthma attacks.
10. Breathing rate will automatically increase
when
10A
a. blood pH is high.
b. the amount of carbon dioxide in the
blood increases.
c. blood acidity decreases.
d. hemoglobin is unloaded.
10A 11C
alveoli are destroyed is called
a. atherosclerosis.
c. emphysema.
b. arteriosclerosis.
d. asthma.
2C 10A
4. The layer labeled A is
a. connective tissue. c. endothelium.
b. smooth muscle.
d. a valve.
11. Which organ receives the richest oxygen
supply from blood returning from the
lungs?
10A 10B
a. stomach
c. heart
b. brain
d. kidney
A
12. Which is not a factor that contributes
to chronic coronary disease?
a. a diet rich in fat
b. unmanaged stress
c. cigarette smoking
d. vigorous exercise
5. For each pair of terms, explain the
differences in their meanings:
a. plasma, lymph
b. blood pressure, pulse
c. heart attack, stroke
10A
6. Lymphatic vessels
a. transport blood.
b. return fluid to the blood.
c. produce antibodies.
d. control blood clotting.
7. What type of blood contains A antibodies
(but not B antibodies) in the plasma and
lacks Rh antigens?
10A
a. AB negative
b. A positive
c. B negative
d. O positive
10A 11C
13.
For what types of athletic
events would blood doping most likely
increase an athlete’s performance? Explain
your reasoning.
11C
14.
One of the effects of
aspirin is that it thins the blood. Why is
aspirin sometimes prescribed for people at
risk for heart attack?
10A 11C
15.
Concept Mapping Make a concept
map that outlines the path of blood
through the body. Try to include the following terms in your map: artery, capillary,
vein, lymphatic system, pulmonary circulation, systemic circulation, atrium, ventricle,
aorta, and vena cava.
2C 3E
Understanding Key Ideas
892
13. Answers will vary but may include any event
that has a significant aerobic component,
such as running, cycling, or swimming.
14. Thinner blood reduces the chances of clot
formation. TAKS 2 Bio 10A; Bio 11C
15. The answer to the concept map is found at
the bottom of the previous page.
TAKS 1 Bio/IPC 2C; Bio 3E
Review and Assess
TAKS Obj 1 Bio/IPC 2C
TAKS Obj 2 Bio 10A, 10B
TEKS Bio 3D, 3E, 3F, 10A, 10B, 11C
TEKS Bio/IPC 2C
892
9. The diaphragm contracts and the pressure
3. A disease in which the elastic fibers in the
Bio 11C
pp. 892–893
10A
8. Blood in the pulmonary veins is
a. oxygen-rich.
c. oxygen-poor.
b. iron-poor.
d. calcium-rich.
Chapter 38 • Circulatory and Respiratory Systems
Assignment Guide
Section
1
2
3
Questions
4, 5, 6, 7, 13, 15, 16, 17, 19, 21
1, 2, 8, 11, 12, 14, 20
3, 9, 10, 18, 22
Critical Thinking
Alternative Assessment
Critical Thinking
16. Forming Reasoned Opinions The frequency
20. Finding Information Use the media center
16. Clotting ability is most likely
diminished because platelets will
not stick as readily.
of blood clots and heart attacks is much
lower among the Inuit, the nomadic
hunters of the North American Arctic, than
it is among other North Americans. This difference is credited to fish oils in the Inuit diet
that cause blood platelets to be more slippery.
How might slippery platelets affect the clotting ability of the Inuit’s blood?
10A 11C
or Internet resources to find out which
foods are recommended as foods that
10A 11C
prevent heart disease.
Drew was an African-American physician.
Write a report that discusses the life of
Dr. Drew and his many accomplishments.
How did his work with blood help save
many lives?
3F
17. Interpreting Information What role do cell
surface markers play in blood typing?
TAKS 2 Bio 10A; Bio 11C
21. Multicultural Perspective Dr. Charles
10A 10B
18. Evaluating Results As altitude increases,
the atmosphere becomes thinner. When a
runner who trained at sea level competes at
a location 500 m above sea level, how will
his or her performance compare with his or
10A 10B 11C
her training performance?
22. Career Connection Respiratory
Therapist Research the field of respiratory
therapy, and write a report on your findings. Your report should include a job
description, training required, kinds of
employers, growth prospects, and
starting salary.
3D
19. Inferring Function How is body tempera-
ture regulated by blood vessel diameter?
10A 10B
17. Cell surface markers called antigens exist on blood cells. Blood
types are named for the antigens
present.
TAKS 2 Bio 10A, 10B (grade 11 only)
18. It will decrease because the runner will not get as much oxygen
as obtained at sea level.
TAKS 2 Bio 10A, 10B (grade 11 only);
Bio 11C
19. Constriction of blood vessels conserves heat. Dilation of blood
vessels increases heat dissipation.
TAKS 2 Bio 10A, 10B (grade 11 only)
Alternative Assessment
TAKS Test Prep
The chart below shows the relationship
between daily salt intake and blood pressure in
humans. Use the chart and your knowledge of
science to answer questions 1–3.
Systolic pressure (mm Hg)
likely have a daily salt intake that does
not exceed
2C 10A
F 4 g.
H 19 g.
G 16 g.
J 27 g.
3. What conclusion can be drawn from
170
the chart?
2C 10A 10B 11C
A Increasing one’s salt intake leads
to an increased systolic pressure.
B Raising one’s systolic pressure leads
to a greater appetite for salt.
C A person can control hypertension by
consuming more salt.
D A daily salt intake of 10 g or less is
associated with a risk to health.
160
150
140
130
120
110
0
2. People with a normal systolic pressure
10
20
30
Daily salt intake (g)
1. A person who consumes 23 g of salt per day
is likely to have a systolic pressure of about
2C 10A
A 120 mm Hg.
C 140 mm Hg.
B 130 mm Hg.
D 150 mm Hg.
1. A. Incorrect. This is the blood pressure associated with about 10 g per day of salt intake.
B. Incorrect. This is the blood pressure associated with about 16 g per day of salt intake.
C. Incorrect. This is the blood pressure associated with about 20 g per day of salt intake.
D. Correct. Consumption of 23 g of salt per
day is correlated with a blood pressure of
150 mm Hg. TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10A
2. F. Incorrect. 16 g is a better choice because 4 g
is not an excessive amount. G. Correct. A
blood pressure of 130 mm Hg is at the high
end of normal and is correlated to 16 g per day
of salt. H. Incorrect. Daily consumption of 19 g
of salt is associated with a blood pressure of
Test
Scan the answer set for words such as “never”
and “always.” Such words often are used in
statements that are incorrect because they are
too general.
893
20. Answers will vary but should
include fish, fresh fruits, vegetables, and foods low in saturated
fat. TAKS 2 Bio 10A; Bio 11C
21. Answers will vary. Dr. Drew
found a way to keep blood
plasma fresh. He also started the
first blood bank. Bio 3F
22. Respiratory therapists treat
patients who have breathing difficulties. Respiratory therapists use
respirators and oxygen tents.
They develop treatment programs
for long-term care, and they operate and maintain oxygen delivery
equipment. Most attend two
years of college with an emphasis
on math and science courses.
Respiratory therapists must be
professionally certified. Many are
employed by hospitals or physicians. The growth prospects of
the field are excellent. Starting
salary will vary by region. Bio 3D
about 140 mm Hg, above normal. J. Incorrect.
Daily consumption of 27 g of salt is associated
with a blood pressure of about 160 mm Hg,
above normal. TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10A
3. A. Correct. There seems to be a direct relationship between salt intake and blood pressure.
B. Incorrect. Increased systolic blood pressure
does not itself increase a person’s appetite for
salt. C. Incorrect. Consuming more salt makes
hypertension worse. D. Incorrect. A daily salt
intake of 10 g or less does not increase blood
pressure above normal nor cause damage in
any other way to the cardiovascular system.
TAKS 1 Bio/IPC 2C; TAKS 2 Bio 10A, 10B (grade 11 only); Bio 11C
Chapter 38 • Circulatory and Respiratory Systems
893