1. Seeley, Stephens and Tate
Essentials of Anatomy and Physiology
Fifth edition
Seeley, Stephens and Tate
Chapter 12: The Heart
Slide 2.1
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

2. The Cardiovascular System
A closed system: heart and blood vessels
The heart pumps blood
Blood vessels allow blood to circulate
A double system:
Pulmonary circuit
Systemic circuit
Slide 11.1
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3. The Cardiovascular System
Functions:
Delivery system for everything!
Remove carbon dioxide and other waste products
Slide 11.1
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4. The Heart Location Size: About the same as your fist
Thoracic cavity, between the lungs
In mediastinum
Pointed apex directed toward left hip
2/3 to left of median plane
Size: About the same as your fist
Slide 11.2a
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5. Location and Orientation within the Thorax
Figure 18.2

6. The Heart: Did You Know…
A blue whale’s heart may weight 1000 pounds (454,000 grams)
It’s the size of a VW beetle!
An elephant heart may weigh 75 pounds
Heart rate about 10 bpm
A mouse’s heart weighs ~ 10 grams
Heart rate about 250 bpm
Slide 11.2a
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7. The Heart: Coverings Pericardium – a double serous membrane
Visceral pericardium
On the surface of the heart
Parietal pericardium
Lines pericardial cavity
Slide 11.3
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8. The Heart: Coverings

9. The Heart: Coverings Pericardial cavity: between layers
Serous fluid fills the space
Fluid required for lubrication
Heart moves!!
Slide 11.3
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10. Structure of the Heart – Coverings
Figure 18.3

11. The Heart Wall Three layers Epicardium Outside layer
This layer is the visceral pericardium
Connective tissue layer
Thin, shiny, slick
Slide 11.4
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12. Structure of the Heart Wall
Epicardium
= visceral pericardium
Figure 18.3

13. The Heart: Heart Wall Myocardium Endocardium Middle layer
Mostly cardiac muscle
Very thick
Endocardium
Inner layer
Endothelium (Simple squamous E.T)
Slick, shiny
Slide 11.4
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14. Structure of the Heart Wall
Myocardium
Endocardium
Figure 18.3

15. The Heart: Chambers Right and left side are separate systems
Four chambers
Atria
Thin walled upper chambers
Receiving chambers
Right atrium (-O2 blood)
Left atrium (+O2 blood)
Slide 11.6
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16. External Heart Anatomy
Figure 11.2a
Slide 11.5
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17. The Heart: Chambers Ventricles Thick walled, lower chambers
Pumping chambers
Right ventricle:
to pulmonary circuit (-O2 blood)
Left ventricle
To systemic circuit (+O2 blood)
Slide 11.6
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18. External Heart Anatomy
Figure 11.2a
Slide 11.5
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19. The Heart: Valves Function: to direct blood flow Two pairs
Atrioventricular valves – between atria and ventricles
Bicuspid (Mitral) valve (left)
Tricuspid valve (right)
“Active”: function with cardiac muscle
Slide 11.8
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20. Heart Valves
Figure 18.5c

21. The Heart: Valves Semilunar valves between ventricle and artery
“Passive”: depend on blood pressure
Pulmonary semilunar valve
RV to pulmonary trunk
Aortic semilunar valve
LV to aorta
Slide 11.8
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22. Heart Valves
Figure 18.5c

23. The Heart: Valves Valves open as blood is pumped through
AV valves held in place by chordae tendineae (“heart strings”)
Close to prevent backflow
Slide 11.9
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24. Heart Valves
Figure 18.5c

25. Operation of Heart Valves
Figure 11.4
Slide 11.10
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26. The Heart: Associated Great Vessels
Great Arteries
Aorta
Leaves left ventricle
Supplies systemic circuit
Pulmonary trunk (artery)
Leaves right ventricle
Supplies pulmonary circuit
Slide 11.11
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27. Great Arteries

28. The Heart: Associated Great Vessels
Great Veins
Venae cavae (superior, inferior)
Enter right atrium
Drain systemic circuit
Pulmonary veins (four)
Enter left atrium
Drain pulmonary circuit
Slide 11.11
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29. Great Vessels
Figure 18.5c

30. Coronary Circulation The heart muscle has its own blood supply
Part of systemic circuit
Coronary arteries (+O2 blood)
Cardiac veins (-O2 blood)
Blood returns to the right atrium via the coronary sinus (-O2 blood)
Slide 11.12
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31. Coronary Circuit, Anterior View
Figure 11.2a
Slide 11.5
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32. Coronary Circuit, Posterior View

33. The Heart: Conduction System
Intrinsic conduction system (nodal system)
Heart muscle cells contract without nerve impulses
Heart has an intrinsic rhythm (“built in”)
Slide 11.13a
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34. The Heart: Conduction System
Specialized cardiac muscle tissue
Sinoatrial (SA) node
Pacemaker
Atrioventricular (AV) node
Atrioventricular bundle (of His)
Bundle branches (R and L)
Purkinje fibers
Slide 11.13b
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35. The Heart: conduction system
Figure 11.5
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36. Heart Contractions
Contraction is initiated by the sinoatrial node: “pacemaker”
Sends information to all muscle cells of both atria
Atria contract simultaneously
Slide 11.14a
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37. The Heart: conduction system
Figure 11.5
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38. Heart Contractions Impulse transmission
AV Node serves as “booster station”
Sends impulse through AV bundle, along bundle branches
Finally to Purkinje fibers
Ventricle muscles contract simultaneously
Slide 11.14a
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39. Heart: conduction system
Figure 11.5
Slide 11.14b
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40. The Heart: Cardiac Cycle
Atria contract simultaneously
Atria relax, then ventricles contract
Systole = contraction of ventricles
Diastole = relaxation of ventricles
Slide 11.16
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41. The Cardiac Cycle Figure 11.6 Slide 11.15
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42. ECG P wave: QRS complex: T wave: Atrial depolarization.
Ventricular depolarization.
Atrial repolarization.
T wave:
Ventricular repolarization.

43. Heart Sounds “Lubb-dupp” – sound of valves closing
First sound “lubb” – the AV valves closing
Second sound “dupp” – the semilunar valves closing

44. The Heart: Cardiac Output
Cardiac output (CO)
Amount of blood pumped by each side of the heart in one minute
CO = (heart rate) x (stroke volume)
Stroke volume
Volume of blood pumped by each ventricle in one contraction
Slide 11.18
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45. Cardiac Output Regulation
Figure 11.7
Slide 11.19
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