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11
The Cardiovascular
System
Lesson 11.1: Heart Anatomy and the
Function of the Cardiovascular System
Lesson 11.2: Regulation of the Heart
Lesson 11.3: Blood Vessels and
Circulation
Lesson 11.4: Heart Disease
Chapter 11: The Cardiovascular System
Lesson 11.1
Heart Anatomy and the
Function of the
Cardiovascular System
Cardiovascular System
• Includes:
– heart, blood vessels, and blood
• Functions:
– transports oxygen, hormones, and other nutrients to
cells
– rids the body of carbon dioxide and other metabolic
waste products
– helps regulate body temp by vasodilation and
vasoconstriction
– assists with immune function
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The Heart
• a normal healthy adult heart beats 72-82 bpm
• located in the thoracic cavity between the lungs
and under the sternum
• centered in the chest and tilted slightly to the left
• sits on the diaphragm
• base is at the top of the heart and apex is at
the bottom of the heart
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The Heart: Location and Size
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The Four Chambers of the Heart
•
•
•
•
•
right atrium and right ventricle
left atrium and left ventricle
atria act as low pressure, collecting chambers
ventricles act as powerful pumps
septums
– prevent oxygen-rich blood from mixing with oxygen-poor
blood
– interatrial septum separates right and left atria
– interventricular septum separates right and left
ventricles
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The Four Chambers of the Heart
• right atrium
– receives deoxygenated blood from the venous system
via the superior vena cava and inferior vena cava
• right ventricle
– pumps blood to the lungs
• left atrium
– receives oxygenated blood from the lungs
• left ventricle
– pumps blood through the aorta to the body
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The Heart Valves
• permit blood to flow only in one direction
• atrioventricular (AV) valves
– located between atria and ventricles
– when open, allow blood to flow from atria to ventricles
– tricuspid
• 3 cusps (flaps)
• located on the right side of the heart
– bicuspid (mitral)
• 2 cusps (flaps)
• located on the left side of the heart
– chordae tendineae
• attach cusps to papillary muscles to secure the AV valves in
place
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The Heart Valves
• semilunar valves
– allow blood to flow from the ventricles to the lungs and
the rest of the body
– consist of 3 semilunar cusps
– pulmonary valve
• located on the right side of the heart at the opening of the
pulmonary artery
– aortic valve
• located on the left side of the heart at the opening of the
aorta
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Blood Flow through the Heart
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Blood Flow Through the Heart
1. Deoxygenated blood enters the right atrium through the
inferior vena cava and superior vena cava
2. The collecting blood in the right atrium increases the
pressure against the tricuspid valve, causing the valve to
open
3. After the right ventricle fills passively with blood, the right
atrium contracts, forcing the remaining blood into the right
ventricle
4. Right ventricle contracts – increasing pressure causes the
tricuspid valve to close and the pulmonary valve to open
forcing the blood into the pulmonary artery
5. Pulmonary artery carries the blood to the lungs where it is
oxygenated
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Blood Flow Through the Heart
6.
Oxygenated blood returns to the left atrium via
the pulmonary veins
7. Blood collecting in the left atrium increases the
pressure in the chamber, forcing the mitral valve
open
8. After the left ventricle fills passively with blood,
the left atrium contracts which forces the
remaining blood into the left ventricle
9. The left ventricle contracts – increasing pressure
causes the mitral valve to close and the aortic
valve to open
10. The oxygenated blood travels through the aorta and to all parts of the
body
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• heart diagram
• heart animation
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Walls of the Heart
• pericardium
– fluid-filled sac
– 3 layers
• fibrous pericardium
– outer wall that anchors the heart to surrounding structures
• parietal pericardium
• epicardium
– parietal pericardium and epicardium are separated by
the fluid-filled pericardial cavity
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The Heart
• 3 layers
– epicardium
• also the innermost layer of the pericardium
• outermost layer of the heart
• surface contains the coronary arteries
– myocardium
• middle layer that makes up about 2/3rds of the heart muscle
• “workhorse” of the heart
– endocardium
• innermost layer
• lines the interior of the heart chambers and covers the valves pf
the heart
• helps blood flow smoothly through the heart
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Cardiac Cycle
• 2 phases – contraction and relaxation
– diastole
• 4 chambers undergo period of relaxation
• chambers fill with blood
• 2nd number of blood pressure reading
– systole
• period of contraction
• chambers are pumping blood out of the heart
• 1st number of blood pressure reading
• 1 cardiac cycle is 0.81 seconds in duration
• 2/3rds of the cardiac cycle is spent in diastole, 1/3rd
is spent in systole
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Cardiac Cycle
• lub-dub sound of heart
– “lub” produced by the closing of the AV valves
– “dub” produced by the closing of the semilunar valves
– an additional sound may indicate a heart murmur when
the valves don’t close properly
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Cardiac Output
• cardiac output
– amount of blood pumped from the heart per minute
(liters/minute)
• stroke volume
– amount of blood pumped from the heart per beat
(mL/beat)
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Review and Assessment
Match these words with 1–4 below: tricuspid,
thoracic cavity, ventricle, aortic.
1. atrioventricular valve
2. semilunar valve
3. location of heart
4. heart chamber
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Blood Flow through the Heart
• (1) deoxygenated blood flows from the body to the
inferior and superior vena cavae to right atrium
• (2) right atrium contracts, forcing blood through the
tricuspid valve to right ventricle
• (3) right ventricle contracts, forcing blood through
the pulmonary valve, to the pulmonary artery
• (4) blood exits to the lungs
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Blood Flow through the Heart (continued)
• (5) oxygenated blood from lungs travels through
the pulmonary veins to the left atrium
• (6) left atrium contracts, forcing blood through the
mitral valve to the left ventricle
• (7) left ventricle contracts, forcing blood through
the aortic valve
• (8) blood passes to the aorta
• (9) blood travels out to parts of the body
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Blood Flow through the Heart
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Walls of the Heart
• epicardium
– outermost layer
• myocardium
– middle layer
• endocardium
– inner layer
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Cardiac Cycle
• diastole
– ventricle relax, atria contract
• systole
– ventricles contract, atria relax
• mean arterial pressure
– overall pressure within cardiovascular system
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Cardiac Output
• amount of blood pumped by heart in 1 minute
measured in liters/minute
• stroke volume
– amount of blood pumped in 1 beat
• heart rate
– number of beats per minute
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Review and Assessment
True or False?
1. The ventricles contract in diastole.
2. Stroke volume is measured in beats/minute.
3. The epicardium is the inner heart layer.
4. Deoxygenated blood enters the left atrium.
5. The aortic valve is in the left ventricle.
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Chapter 11: The Cardiovascular System
Lesson 11.2
Regulation of the Heart
Regulation of the Heart
• internal control of the heart
– sinoatrial node (SA node)
• also called the pacemaker
• located at the top of the right atrium
• sends out an electrical impulse that tells the heart to beat
at a rate of between 60 and 100 bpm
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Regulation of the Heart
• external control
– cardiac center
• located in the medulla oblongata
• consists of sympathetic and parasympathetic branches
– sympathetic stimulation
» increases the heart rate
» affected by emotions and physical activity
– parasympathetic stimulation
» decreases the heart rate
» dominant when you are at rest
» releases acetylcholine to decrease heart rate
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Regulation of the Heart
• External control (cont’d)
– endocrine system
• adrenal medulla
– secretes epinephrine and norepinephrine to increase heart
rate
• thyroid gland
– releases thyroxine to increase heart rate
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The Conduction System
1. SA node sends the electrical impulse to the left
atrium and to the atrioventricular node (AV node).
2. The electrical impulse is delayed briefly at the AV
node.
3. The impulse travels down the left bundle
branches and right bundle branches to the
Purkinje fibers in both the left and right ventricles.
4. The Purkinje fibers stimulate the ventricles to
contract
Heart Diagram
Conduction Animation
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The Conduction System
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Electrocardiogram
• ECG or EKG
– electrical activity of the heart
– when the atria and ventricles contract = depolarize
– when the atria and ventricles relax = repolarize
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Electrocardiogram
Electrical Event
Mechanical Event
ECG Recording
SA node fires
Atria contract
P wave
Impulse travels to
Purkinje fibers
Ventricles contract
QRS complex
Ventricles relax
Atria and ventricles fill
T wave
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Review and Assessment
Match these words with 1–4 below: parasympathetic,
EKG, SA node, sympathetic.
1. speed up
2. slow down
3. pacemaker
4. electrical activity of the heart
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Cardiac Arrhythmias
• normal contractility condition
– sinus rhythm
• abnormal contractility condition
– arrhythmia
• ventricle or atria contraction is not
normal
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Cardiac Arrhythmias
• bradycardia
– slow heart beat
• tachycardia
– fast heart beat
• premature atrial
contraction (PACs)
– atria contracts before
SA node
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Cardiac Arrhythmias
• atrial fibrillation
– atria contract faster than 350
bpm
• premature ventricular
contractions (PVCs)
– ventricles contract too soon
• ventricular tachycardia (VT)
– ventricles, rather than SA
node, cause beat
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Cardiac Arrhythmias
• ventricular fibrillation (VF)
– ventricles contract faster
than 350 bpm
• heart block
– impulse from SA node to
AV node
• first–impulse delayed
• second–intermittently
blocked
• third–completely blocked
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Defibrillators and Life-Threatening
Arrhythmias
• automatic external defibrillator (AED)
–
–
–
–
electric shock
stops heart
allows heart to start normal rhythm
anyone can use one
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Review and Assessment
Fill in the blanks with: Tachycardia, Atrial fibrillation,
Bradycardia, or Defibrillator.
1. _______________ is fast heart beat.
2. _______________ is slow heart beat.
3. _______________ is atria beating more than 350
bpm.
4. A(n) _______________ stops the heart so it can
reset.
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Chapter 11: The Cardiovascular System
Lesson 11.3
Blood Vessels and
Circulation
Blood Vessels and Circulation
•
•
•
•
blood vessels: the transport network
circulation: moving blood around the body
taking vital signs
know your numbers
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Blood Vessels: The Transport Network
• structure and function of vessels
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The Three Layers of Blood Vessels
• tunica intima
– innermost layer
• tunica media
– middle layer
• tunica externa
– outermost layer
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Differences between Arteries and Veins
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Capillaries
• exchange vessels
– gas moves between tissue and blood
• capillary bed
– network of exchange vessels
• precapillary sphincters
– close off capillary bed as needed
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Circulation: Moving Blood around the
Body
• cardiopulmonary circulation
– between heart and lungs
• systemic circulation
– between heart and body
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Circulation: Moving Blood around the
Body
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Review and Assessment
True or False?
1. Systemic circulation moves blood to lungs.
2. Capillaries are exchange vessels.
3. The tunica intima is the innermost layer.
4. Arteries move blood away from the heart.
5. Veins move blood toward the heart.
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Cardiac Circulation
• coronary arteries
– left
– right
• coronary sinus
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Hepatic Portal Circulation
• maintains proper levels in the blood
– carbohydrate
– fat
– protein
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Arteries
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Veins
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Fetal Circulation
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•
•
•
•
•
placenta
vena cava
right atrium
foramen ovale
right ventricle
ductus arteriosus
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Taking Vital Signs
• taking your pulse
– find radial, carotid or brachial artery
– count beats for 15 seconds, multiply by 4
• measuring blood pressure
– stethoscope, sphygmomanometer
– systolic/diastolic pressure
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Know Your Numbers
• weight
– body mass index–weight to height
• blood pressure
– systolic/diastolic–110/70 mmHg
• cholesterol
– LDLs and HDLs
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Review and Assessment
Match these words with 1–4 below: foramen ovule,
cholesterol, pulse, blood pressure.
1. systolic/diastolic
2. fetal circulation
3. LDLs and HDLs
4. carotid artery
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Chapter 11: The Cardiovascular System
Lesson 11.4
Heart Disease
Heart Disease
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•
•
•
valve abnormalities
diseases ending in -itis
heart failure
diseases of the arteries
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Heart Disease
•
•
•
•
heart attack
hypertension
peripheral vascular disease
stroke
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Valve Abnormalities
• heart murmurs
– valves do not close properly
• valvular stenosis
– narrowed, stiff heart valve
• mitral valve prolapse
– mitral valve does not fully close
• palpitations
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Diseases Ending in -itis
• pericarditis
– inflammation of heart sac
• myocarditis
– inflammation of heart muscle
• endocarditis
– inflammation of heart lining and valves
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Heart Failure
• heart cannot pump blood
• fluid backs up in
–
–
–
–
lungs
liver
limbs
gastrointestinal tract
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Diseases of the Arteries
• aneurysms
– weakened artery bulges,
may break
• coronary artery disease
– atherosclerosis
– angina pectoris
– ischemia
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Heart Attack
• myocardial infarction
– plaque blocks a cardiac artery
• treatment
– aspirin as soon as symptoms appear
– 20–60 minute window for treatment
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Heart Attack
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Heart Disease
• hypertension
– blood pressure above 140/90 mmHg
• peripheral vascular disease
– lack of circulation in legs
• stroke
– blockage of brain blood flow
• ischemic stroke
• hemorrhagic stroke
• transient ischemic attack (TIA)
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Review and Assessment
True or False?
1. Hypertension is 120/80 mmHg.
2. Aspirin helps in a heart attack.
3. An aneurysm is a weakened artery.
4. Myocarditis affects the heart wall.
5. In a heart murmur the valves do not close
properly.
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