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Essentials of Human Anatomy & Physiology
Elaine N. Marieb
Seventh Edition
Chapter 11
The Cardiovascular
System
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
The Cardiovascular System
 A closed system of the heart and blood
vessels
 The heart pumps blood
 Blood vessels allow blood to circulate to all
parts of the body
 The function of the cardiovascular
system is to deliver oxygen and
nutrients and to remove carbon dioxide
and other waste products
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.1
The Heart
 Location
 Thorax between the lungs
• Called the Mediastinum
 About the size of your fist
 Less than 1 lb.
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The Heart
Figure 11.1
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The Heart: Coverings
 Pericardium – a double serous
membrane
The Heart: Heart Wall (3 Layers)
 Epicardium
 Outside layer
 Connective tissue layer
 Myocardium
 Middle layer
 Mostly cardiac muscle
 Endocardium
 Inner layer
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Slide 11.3
External Heart Anatomy
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Figure 11.2a
Slide 11.5
The Heart: Chambers
 Right and left side act as separate pumps
 Four chambers
 Atria (Superior)
 Receiving chambers: Small with thin walls
 Right atrium
 Left atrium
 Ventricles (Inferior)
 Discharging chambers: Big with thick walls
 Right ventricle
 Left ventricle
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Slide 11.6
Blood Vessels
 Arteries: “Superhighways”
 Carry blood away from the heart to the body
 Thick elastic walls to withstand spurts of
blood produced by heart contractions
• Veins: “Roads”
• Thin walled and less elastic
• Collect blood after it passes through
capillaries and sends blood back to the heart
Blood Vessels
• Capillaries: “Side-streets and alleys”
• Smallest, microscopic vessels
• Wastes and nutrients are diffused through
capillary membranes into and out of cells
Blood Circulation
Figure 11.3
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Slide 11.7
Pathway of Blood
• Pulmonary Circuit
• Right side of heart  heart to lungs back to heart
• Oxygen poor and carbon dioxide rich blood
• Short, low pressure circuit
• Right ventricle is not as thick as the left
Pathway of Blood
• Systemic Circuit
• Left side of the heart
 from heart to body
to heart
• Oxygen rich and
carbon dioxide poor
blood
• Long, high pressure
circuit because it
pumps to entire body
• Left ventricle is 3x as
thick as the right
Pathway of Blood
1. Superior/Inferior Vena Cavae
2. Right Atrium
3. Right Ventricle
4. Pulmonary Artery
5. Lungs
6. Pulmonary Veins
7. Left Atrium
8. Left Ventricle
9. Aorta
10. Arteries and Capillaries
11. Veins back to the Heart
The Heart: Valves
 Allow blood to flow in only one direction
 Four valves
 Atrioventricular valves – between atria and
ventricles
 Bicuspid valve (left)
 Tricuspid valve (right)
 Semilunar valves between ventricle and
artery
 Pulmonary semilunar valve
 Aortic semilunar valve: guards base of artery
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Slide 11.8
The Heart: Valves
 Valves open as blood is pumped
through
 Held in place by chordae tendineae
(“heart strings”)
 Close to prevent backflow
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Slide 11.9
Operation of Heart Valves
Figure 11.4
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Electrocardiograms (EKG/ECG)
• A graphic picture of cardiac conduction cycle
• Three formations “waves”
– P wave: Atria depolarize and contract
– Small, lasts .08 seconds
– QRS complex: ventricles depolarize and contract
– Larger, lasts .08 seconds
– T wave: ventricles repolarize and relax
– More spread out, low height
Electrocardiograms (EKG/ECG) (cont.)
Figure 8.15B, C
Blood Pressure
 Measurements by health professionals are
made on the pressure in large arteries
 Force exerted by blood against inner walls of
blood vessels
 Systolic – left ventricle; contracting and pushing
blood into Aorta causes pressure to peak
 Diastolic – amount of pressure that the Aorta
and Arteries can maintain on reducing blood
volume. Ex: 120/70
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Measuring Arterial Blood Pressure
Figure 11.18
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Variations in Blood Pressure
 Human normal range is variable
 Normal
 140–110 mm Hg systolic
 80–75 mm Hg diastolic
 Hypotension
 Low systolic (below 110 mm HG)
 Often associated with illness
 Hypertension
 High systolic (above 140 mm HG)
 Can be dangerous if it is chronic
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Heart Sounds
 “Lub-dub”: closing of the heart valves
 1st Sound: “Lub”  AV valves closing
 2nd Sound: “Dub”  Semi-lunar valves closing
 Heart Murmurs
 Indicate valve problem (Ex: Leaky Valve)
 Pacemaker
 Small mass of cells on the posterior of right
atrium just inferior to superior vena cava
 They “excite” themselves and initiate rhythmic
contractions of the heart, the S-A node
The Heart: Cardiac Output
 Cardiac output (CO)
 Amount of blood pumped by each side of the
heart in one minute
 CO = (heart rate [HR]) x (stroke volume [SV])
 Stroke volume
 Volume of blood pumped by each ventricle in
one contraction
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Cardiac output, cont.
• CO = Heart Rate x Stroke Volume
– Normal = 5000 ml/min
Example: HR= 75 beats/min
SV= 70 mL/ beat
CO=?
CO= 75 x 70
CO= 5250 ml/min= 5.25 L/min
• Entire blood supply passes through body once per
minute.
• CO varies with demands of the body.
Cardiac Reserve
 The ability of the heart to push its
cardiac output beyond normal limit
depends on the person
 Most can push their CO up to 4x
beyond normal, whereas trained
athletes can push their CO up to 7x
above normal
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Sterling’s Law of the Heart
 The enlargement of the ventricular chambers
drives stroke volume and the force of heart
contractions
 The more blood received by the right atrium
through the SVC and IVC the stronger the
ventricular contraction and the greater the
stroke volume and cardiac output
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