1. Section 4.2 The Heart
 Chapter 18, pp. 661-687
 Keep an eye on the Forum over the next few days
for a new question
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

2. Heart Anatomy
 Approximately the size of your fist
 Two side-by-side pumps
 Location
 Superior surface of diaphragm
 Left of the midline, from 2nd rib to 5th intercostal
space
 Anterior to the vertebral column, posterior to the
sternum
 “mediastinum”
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

3. Heart Anatomy Broad, flat base points to rt. shoulder
Apex points to lt. hip
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.1

4. 3 layers of the heart
 Pericardium
 Outer sac
 Myocardium
 Muscle, bulk of mass
 Endocardium
 Inner lining
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

5. Coverings of the Heart: Anatomy
 Pericardium – a double-walled sac around the heart
composed of:
 A superficial fibrous pericardium
 A deep two-layer serous pericardium
 The parietal layer lines the internal surface of
the fibrous pericardium
 The visceral layer or epicardium lines the
surface of the heart
 They are separated by the fluid-filled pericardial
cavity
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

6. Coverings of the Heart: Physiology
 The pericardium:
 Protects and anchors the heart
 Prevents overfilling of the heart with blood
 Allows for the heart to work in a relatively friction-
free environment
 Epicardium – visceral layer of the serous
pericardium
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

7. Pericardial Layers of the Heart
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.2

8. Heart Wall
 Myocardium – cardiac muscle layer forming the bulk of
the heart
 Branching muscle cells arranged in bundles
 Provides support for great vessels and valves
 Directs spread of action potentials across heart
 Fibrous skeleton of the heart – crisscrossing, interlacing
layer of connective tissue, insulation, supports great vessels
 Endocardium – endothelial layer of the inner myocardial
surface; continuous with vessels leaving and entering the
heart
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

9. Cardiac Muscle Bundles
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.3

10. External Heart: Major Vessels of the Heart
(Anterior View)
 Vessels returning blood to the heart include:
 Superior and inferior venae cavae, meaning?
 Right and left pulmonary veins
 Vessels conveying blood away from the heart:
 Pulmonary trunk, which splits into right and left pulmonary
arteries
 Ascending aorta (three branches) – brachiocephalic, left
common carotid, and subclavian arteries
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

11. External Heart: Vessels that Supply/Drain the
Heart (Anterior View)
 Arteries – right and left coronary (in
atrioventricular groove), marginal, circumflex, and
anterior interventricular arteries
 Veins – small cardiac, anterior cardiac, and great
cardiac veins
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

12. Brachiocephalic Left common
trunk carotid artery
Superior Left
vena cava subclavian artery
Aortic arch
Right
Ligamentum
pulmonary artery
arteriosum
Ascending Left pulmonary artery
aorta
Pulmonary trunk Left pulmonary veins
Left atrium
Right
pulmonary veins Auricle
Right atrium Circumflex
Right coronary artery
artery (in coronary Left coronary
sulcus) artery (in coronary
Anterior sulcus)
cardiac vein Left ventricle
Right ventricle
Marginal artery Great cardiac vein
Small cardiac vein Anterior
Inferior interventricular artery
(in anterior
vena cava interventricular sulcus)
Apex
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4b

13. External Heart: Major Vessels of the Heart
(Posterior View)
 Vessels returning blood to the heart include:
 Right and left pulmonary veins
 Superior and inferior venae cavae
 Vessels conveying blood away from the heart
include:
 Aorta
 Right and left pulmonary arteries
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

14. External Heart: Vessels that Supply/Drain the
Heart (Posterior View)
 Arteries – right coronary artery (in atrioventricular
groove) and the posterior interventricular artery (in
interventricular groove)
 Veins – great cardiac vein, posterior vein to left
ventricle, coronary sinus, and middle cardiac vein
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

15. Aorta Superior
vena cava
Left Right
pulmonary artery pulmonary artery
Left
pulmonary veins Right
pulmonary veins
Auricle
of left atrium Right atrium
Left atrium
Inferior
Great cardiac vein vena cava
Right coronary
Posterior vein artery (in coronary
of left ventricle sulcus)
Coronary sinus
Posterior
interventricular artery
Left ventricle (in posterior
interventricular sulcus)
Apex Middle cardiac vein
(d) Right ventricle
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4d

16. Aorta
Superior vena cava
Left
Right pulmonary artery
pulmonary artery Left atrium
Pulmonary trunk
Left
Right atrium pulmonary veins
Right
pulmonary veins Mitral
Fossa (bicuspid-2 flaps)
ovalis valveAortic
Pectinate valve
Pulmonary
muscles valve
Tricuspid Left ventricle
Valve (3 flaps)
Papillary
Right ventricle
muscle
Chordae Interventricular
tendineae septum
Trabeculae Myocardium
carneae Visceral
Inferior pericardium
vena cava Endocardium
(e)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4e

17. Atria of the Heart
 Atria are the receiving chambers of the heart
 Each atrium has a protruding auricle
 Pectinate muscles mark atrial walls
 Blood enters right atria from superior and inferior
venae cavae and coronary sinus
 Blood enters left atria from pulmonary veins
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

18. Ventricles of the Heart
 Ventricles are the discharging chambers of the
heart
 Papillary muscles and trabeculae carneae muscles
mark ventricular walls
 Right ventricle pumps blood into the pulmonary
trunk
 Left ventricle pumps blood into the aorta
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

19. Right and Left Ventricles
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.6

20. Pathway of Blood Through the Heart and
Lungs
 Right atrium  tricuspid valve  right ventricle
 Right ventricle  pulmonary semilunar valve 
pulmonary arteries  lungs
 Lungs  pulmonary veins  left atrium
 Left atrium  bicuspid valve  left ventricle
 Left ventricle  aortic semilunar valve  aorta
 Aorta  systemic circulation
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

21. Aorta
Superior vena cava
Left
Right pulmonary artery
pulmonary artery Left atrium
Pulmonary trunk
Left
Right atrium pulmonary veins
Right
pulmonary veins Mitral
Fossa (bicuspid) valve
ovalis Aortic
Pectinate valve
Pulmonary
muscles valve
Tricuspid Left ventricle
valve
Papillary
Right ventricle
muscle
Chordae Interventricular
tendineae septum
Trabeculae Myocardium
carneae Visceral
Inferior pericardium
vena cava Endocardium
(e)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4e

22. Pulmonary circuit:
Shorter, low
pressure
Systemic circuit:
Long pathway, 5x
pressure (more
resistance)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.5

23. 2 side-by-side pumps
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

24. Coronary Circulation
 Coronary circulation is the functional blood supply
to the heart muscle itself
 Collateral routes ensure blood delivery to heart
even if major vessels are occluded
Left coronary artery Right coronary artery
anterior circumflex marginal posterior
interventricular artery artery interventricular
artery artery
interventricular left atrium lateral right posterior right
septum & & posterior side of ventricular
anterior walls walls of left heart (incl walls
of both ventricle right atrium
ventricles
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

25. Coronary Circulation: Arterial Supply
Blockage results in:
Angina pectoris
Myocardial
Infarction (MI)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.7a

26. Coronary circulation
• many anastomoses, which provide alternate routes for nourishment if a
given artery begins to be occluded - but total occlusion means ????
(1) actively deliver blood when heart is relaxed
(2) largely ineffective when ventricles contracting because??
• heart ~1/200 of body but requires ~1/20 of blood supply (esp. left ventricle)
Coronary venous supply:
from capillaries → cardiac veins (great,
middle & small) → coronary sinus →
right atrium
also some anterior cardiac veins →
directly into right atrium anteriorly
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

27. Coronary Circulation: Venous Supply
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.7b

28. Aorta Superior
vena cava
Left Right
pulmonary artery pulmonary artery
Left
pulmonary veins Right
pulmonary veins
Auricle
of left atrium Right atrium
Left atrium
Inferior
Great cardiac vein vena cava
Right coronary
Posterior vein artery (in coronary
of left ventricle sulcus)
Coronary sinus
Posterior
interventricular artery
Left ventricle (in posterior
interventricular sulcus)
Apex Middle cardiac vein
(d) Right ventricle
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.4d

29. Heart Valves
 Heart valves ensure unidirectional blood flow
through the heart
 Atrioventricular (AV) valves lie between the atria
and the ventricles
 AV valves prevent backflow into the atria when
ventricles contract
 Chordae tendineae anchor AV valves to papillary
muscles
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

30. Heart Valves
 Aortic semilunar valve lies between the left
ventricle and the aorta
 Pulmonary semilunar valve lies between the right
ventricle and pulmonary trunk
 Semilunar valves prevent backflow of blood into
the ventricles
 No valves for vena cavae and pulmonary veins!
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

31. Heart Valves
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.8a, b

32. Heart Valves
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.8c, d

33. Atrioventricular Valve Function
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.9

34. Semilunar Valve Function
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.10

35. Microscopic Anatomy of Heart Muscle
 Cardiac muscle is striated, short, fat, branched, and
interconnected
 The connective tissue endomysium acts as both
tendon and insertion
 Intercalated discs anchor cardiac cells together and
allow free passage of ions
 Heart muscle behaves as a functional syncytium
PLAY InterActive Physiology ®:
Anatomy Review: The Heart, pages 3–7
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

36. Microscopic Anatomy of Cardiac Muscle
•1 or 2 nuclei/cell
•full of mitochondria
(25% vs 2% skeletal)
•Resist fatigue
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 18.11