1. Chapter 17 Overview
Layers of heart tissue
Heart Chambers
Valves
Heart contraction
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2. Heart Anatomy
• Fist sized organ
• Located in mediastinum
• between 2nd and 5th rib
• 2/3 to the left
• Enclosed by pericardium, a double-walled sac
Midsternal line
2nd rib
Sternum
Diaphragm
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3. Pericardium
• Outer fibrous layer
• Anchors heart
• Parietal layer lines fibrous layer
• Visceral layer (epicardium) contacts heart
• Separated by pericardial fluid
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4. Layers of the Heart Wall
1. Epicardium — inner pericardium layer
2. Myocardium - cardiac muscle layer
3. Endocardium - inner layer of heart
Pulmonary
trunk
Pericardium
Myocardium
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Fibrous pericardium
Parietal pericardium
Pericardial cavity
Epicardium
(visceral
Heart
pericardium) wall
Myocardium
Endocardium
Heart chamber

5. Chambers of the Heart
• Four chambers
• Two atria (patient’s right and left)
• Two ventricles (patient’s right and left)
• Separated by septum
• interatrial
• interventricular
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6. Left atrium
Right atrium
Right ventricle
Left ventricle
(b) Anterior view
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Figure 17.4b

7. Atria: The Receiving Chambers
• Right atria
• Left atria
• Low O2 blood
• High O2 blood
• Blood from:
• Blood from:
• Sup. & inf. Vena cava
• Coronary sinus
Sup. Vena cava
Right atria
R. pulm. vein
Inf. Vena cava
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• R & L pulmonary veins
• From lungs
L. Pulmonary
vein
Left atria

8. Ventricles: The Discharging Chambers
Aorta
• Right ventricle
• pumps blood to the lungs
• Via pulmonary trunk
Pulmonary
trunk
• Left ventricle
• Pumps blood to the body
• Via the aorta
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Right
ventricle
Left
ventricle

9. Heart Valves
• Ensure unidirectional flow
• Two major types
1. Atrioventricular valves
2. Semilunar valves
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10. Heart Valves
1. Atrioventricular (AV) valves
•
Separates atria from
ventricles
•
Tricuspid valve (right side)
•
Mitral valve (left side)
• a.k.a bicuspid valve
Tricuspid
valve
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Mitral valve

11. Heart Valves
• Semilunar (SL) valves
• Separate ventricles from circulation
• Aortic semilunar valve
• Left ventricle / aorta
• Pulmonary semilunar valve
• Right ventricle / pulmonary trunk
Pulmonary
SL
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Aortic SL

12. Copyright © 2011 Pearson Education, Inc.

13. Left atrium
Right atrium
Mitral (bicuspid)
valve
Aortic valve
Tricuspid valve
Right ventricle
Chordae tendineae
Pulmonary valve
Left ventricle
Papillary muscle
(e) Frontal section
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Figure 17.4e

14. PATHWAY OF BLOOD
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15. Pathway of Blood Through the Heart
• The heart is basically two pumps
• Right side
• Pulmonary circuit
• to the lungs
• Left side
• Systemic circuit
• to the body
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16. Pathway of Blood Through the Heart
• R. atrium  tricuspid
valve  R. ventricle 
pulmonary valve 
pulmonary trunk 
pulmonary arteries 
lungs
• Blood through R. atrium &
ventricle is low O2
• In lungs becomes high O2
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17. Pathway of Blood Through the Heart
• High O2 blood enters left
atrium
• Lungs  pulmonary veins
 L. atrium  bicuspid
valve  L. ventricle 
aortic semilunar valve 
aorta  systemic
circulation
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18. Pathway of Blood Through the Heart
Pulmonary
Circuit
Pulmonary arteries
Venae cavae
Capillary beds
of lungs where
gas exchange
occurs
Pulmonary veins
Aorta and branches
Left atrium
Left ventricle
Right atrium
Right ventricle
Oxygen-rich,
CO2-poor blood
Oxygen-poor,
CO2-rich blood
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Heart
Systemic
Circuit
Capillary beds of all
body tissues where
gas exchange occurs
Figure 17.5

19. Pathway of Blood Through the Heart
• Left ventricle pumps blood through entire
body
• Thick myocardium, to generate large force
• Right ventricle pumps blood to lungs
• Thinner myocardium
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20. Coronary Circulation
• Supplies the heart with blood
• The heart is a muscle that requires its own blood supply
• Arteries
• Right and left coronary arteries
• Veins
• Coronary sinus, drains blood into the right
atrium
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21. Coronary vessels
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