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37–1 The Circulatory System
I. Functions of the Circulatory System
A. Needed in large organisms since most of their
cells are not in direct contact with the
environment
B. Like the transportation system in a city
C. Consists of:
1. the heart
2. blood vessels
3. Blood
II. The Heart
A hollow organ made almost entirely of muscle
Enclosed in a protective sac = pericardium
Septum separates left from right
Chambers that receive blood = atrium (atria)
Chambers that pump blood out = ventricle
Circulation through the heart
1. Valves between the atria and ventricles
2. Valves also prevent backflow of blood
A.
B.
C.
D.
E.
F.
G. Circulation through the Body
1. Pulmonary circulation
a. The right side of the
heart pumps blood
from the heart to the
lungs (O2 poor blood)
2. Systemic circulation
a. The left side of the
heart pumps blood
from the heart to the
rest of the body (O2
rich blood)
III. Blood Vessels
A. 3 types of blood vessels:
1. Arteries = Large vessels with thick walls that
carry O2 rich blood from the heart to the
tissues
2. Capillaries = smallest blood vessels with
walls only 1 cell thick so nutrients, wastes,
CO2, and O2 can diffuse between tissues and
blood
3. Veins = vessels with thinner walls than
arteries which carry O2 poor blood back to
the heart
IV. Diseases of the Circulatory System
A. Cardiovascular diseases are among the leading
causes of death and disability in the U.S.
B. Atherosclerosis = fatty deposits called plaque build
up on the inner walls of the arteries (can lead to high
blood pressure)
C. Heart Attack and Stroke
1. Heart attack occurs if one of the coronary arteries
becomes blocked
2. Stroke occurs if a blood clot gets stuck in a blood
vessel leading to the brain
37–2 Blood and the Lymphatic
System
I. Blood
A. Blood contains both dissolved substances and
specialized cells
B. The functions of blood include:
1. collecting O2 from the lungs, nutrients from the
digestive tract, and waste products from
tissues
2. regulating the body’s internal environment
3. helping to fight infections
4. forming clots to repair damaged blood
vessels
C. Plasma
1. The body has 4-6 Liters of blood
2. About 45% of blood volume is cells
3. The other 55% is plasma
D. Red Blood Cells
1. The most numerous cells in the blood
2. Transport oxygen
3. Are produced in bone marrow
4. Have no nuclei
5. Live for about 120 days
White Blood cells
1. Also produced in bone marrow
2. Have a nucleus
3. May live for days, months, or years
4. Are the “army” of the circulatory system
a. Guard against infection
b. Fight parasites
c. Attack bacteria
F. Platelets & Blood Clotting
1. Clotting is a mechanism to slow bleeding and
start healing
2. Made possible by plasma proteins & platelets!
E.
II. Lymphatic System
A. As blood circulates through the body, fluid leaks into
the surrounding cells
B. A network of vessels, nodes, and organs collects the
“lost” fluid and returns it back to the circulatory
system
C. Lymph nodes act as filters and trap bacteria and
other microorganisms
D. Lymph vessels absorb fats and fat soluble vitamins
from the digestive system
E. Thymus and the spleen are organs that play a role in
this system
37-3 The Respiratory System
I. What Is Respiration?
A. Respiration means 2 things:
1. Cellular respiration = release of energy from
the breakdown of food in the presence of
oxygen
2. Respiration = process of gas exchange—the
release of CO2 and the uptake of O2 between
the lungs and the environment
3. The basic function is the exchange of O2 and
CO2 between the blood, the air, and tissues
B. Air entering the nose must be warmed,
moistened, and filtered (mucous & cilia)
C. Pharynx serves as a passageway for both air
and food
1. Epiglottis covers entrance to trachea when
you swallow
2. At top of trachea is the larynx (vocal cords)
D. Air moves from pharynx  trachea  (bronchi
bronchioles  alveoli)
Pharynx
Nose
Larynx
Mouth
Alveoli
Trachea
Epiglottis
Lungs
Bronchus
Bronchioles
Diaphragm
Capillaries
O2
II. Gas Exchange
A. Gas exchange takes
place in the alveoli
1. O2 diffuses into the
blood
2. CO2 in the blood
leaves and diffuses
into the alveolus
Capillary
O2
CO2
III. Breathing
A. Breathing is the movement of air into and out of
the lungs
B. The force that drives air into the lungs comes
from air pressure
C. Lungs are sealed in membranes inside the chest
cavity
D. At the bottom of the cavity is a large, flat
muscle known as the diaphragm
1. Inhalation = the diaphragm contracts,
increase volume of chest cavity, air goes in
2. Exhalation = diaphragm relaxes, air forced
out by decrease in chest cavity volume
What controls breathing?
(Hint: we talked about it in Ch. 35)
Inhalation
Diaphragm contract
Rib cage rises &
increases volume in
chest
Exhalation
Diaphragm relaxes
Rib cage lowers &
decreases volume in
chest