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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
 Function: 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
 Pointed apex directed toward left hip
 Base points toward right shoulder
 About the size of your fist
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Slide 11.2a
The Heart
Figure 11.1
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Slide 11.2b
The Heart: Coverings
 Pericardium – a double serous
membrane
 Visceral pericardium
 Next to heart
 Parietal pericardium
 Outside layer
 Serous fluid fills the space between the
layers of pericardium
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.3
The Heart: Heart Wall
 Three layers
 Epicardium
 Outside layer
 This layer is the parietal pericardium
 Connective tissue layer
 Myocardium
 Middle layer
 Mostly cardiac muscle
 Endocardium
 Inner layer
 Endothelium
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Slide 11.4
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
 Receiving chambers
 Right atrium
 Left atrium
 Ventricles
 Discharging chambers
 Right ventricle
 Left ventricle
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.6
Internal Heart Anatomy
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Slide 11.6
Blood Circulation
Figure 11.3
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Slide 11.7
Pulmonary Circuit
 Function—carry blood to lungs for gas
exchange and return it to the heart
 Blood vessels involved
 Pulmonary arteries—carry oxygen-poor
blood to the lungs away from the heart
 Pulmonary veins—carry oxygen-rich blood
to the heart from the lungs
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.8
Systemic Circuit
 Function—carries oxygen- and nutrientrich blood to all body organs, and carries
oxygen-poor blood back to heart
 Blood vessels involved
 Arteries—carries oxygen-rich blood from
heart to body
 Veins—carries oxygen-poor blood from
body to heart
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.8
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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.9
Operation of Heart Valves
Figure 11.4
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Slide 11.10
The Heart: Associated Great Vessels
 Aorta
 Leaves left ventricle
 Pulmonary arteries
 Leave right ventricle
 Vena cava
 Enters right atrium
 Pulmonary veins (four)
 Enter left atrium
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.11
Coronary Circulation
 Blood in the heart chambers does not
nourish the myocardium
 The heart has its own nourishing
circulatory system
 Coronary arteries
 Cardiac veins
 Blood empties into the right atrium via the
coronary sinus
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.12
Circulatory homeostatic imbalances
 Angina pectoris
 Myocardium is deprived of oxygen when
there is not enough blood supply,
resulting in crushing chest pain
 Myocardial infarction
“heart attack” or “coronary”
Ischemic (decrease in blood supply)
heart cells die forming an infarct
(region of dead tissue)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.12
The Heart: Conduction System
 Intrinsic conduction system
(nodal system)
 Heart muscle cells contract, without nerve
impulses, in a regular, continuous way
 Enforces contraction rate of ~75 beats/min
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.13a
The Heart: Conduction System
 Special tissue sets the pace
1. Sinoatrial node—pacemaker (highest
rate of depolarization, starts each
heartbeat)
2. Atrioventricular node
3. Atrioventricular bundle (Bundle of His)
4. Bundle branches (right and left)
5. Purkinje fibers
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Slide 11.13b
Heart Contractions
Figure 11.5
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Slide 11.14b
The Heart: Cardiac Cycle
 Cardiac cycle – events of one complete heart
beat (~0.8 sec)
 Atrial systole and diastole followed by ventricular
systole and diastole
 Atria contract simultaneously
 Atria relax, then ventricles contract
 Most pumping is done by ventricles
 Systole = contraction
 Diastole = relaxation
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.16
The Heart: Cardiac Cycle
 Mid-to-late diastole (relaxation) – blood flows
into ventricles
 Ventricular systole – blood pressure builds
before ventricle contracts, pushing out blood
(atria are relaxed and filling with blood)
 Early diastole – atria finish re-filling,
ventricular pressure is low, semilunar valves
shut
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.17
Slide 11.17
The Heart: Cardiac Cycle
Mid-to-late Diastole Ventricular Systole
Early Diastole
1.
PRESSURE LOW
1.
PRESSURE HIGH
1.
PRESSURE LOW
2.
AV VALVES OPEN
2.
AV VALVES CLOSE
2.
AV VALVES OPEN
3.
SEMILUNAR
VALVES CLOSED
3.
3.
4.
BLOOD FLOWS
INTO
VENTRICLES
SEMILUNAR
VALVES FORCED
OPEN
SEMILUNAR
VALVES SNAP
SHUT
4.
BLOOD PUSHED
OUT OF
VENTRICLES INTO
PULMONARY
TRUNK/AORTA
4.
VENTRICLES
REFILL WITH
BLOOD
5.
ATRIA BEGIN TO
CONTRACT,
VENTRICLES
RELAX
5.
ATRIA
CONTRACT,
VENTRICLES
RELAX
5.
ATRIA RELAX,
VENTRICLES
CONTRACT
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Filling of Heart Chambers –
the Cardiac Cycle
Figure 11.6
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Slide 11.15
Heart Sounds
 Lub-dup, pause, lub-dup, pause…
 Lub-first sound louder and longer when
AV valves close
Signifies start of systole when
ventricular pressure rises above atrial
pressure
 -dup-sharp sound when SL valves snap
shut
Signifies start of ventricular diastole
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.14a
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
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.18
Cardiac Output Regulation
Figure 11.7
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Slide 11.19