1. 19
The Heart

2. I. Circuits and Chambers
The heart is a muscular double pump
A. Pulmonary circuit: Right side receives oxygen-poor blood from the body and pumps it to the lungs
B. Systemic circuit: Left side receives oxygenated blood from lungs and pumps throughout the body
Atria = Receive blood from the pulmonary and systemic circuit
Ventricles = Pump blood to the pulmonary and systemic circuit 2

3. Pulmonary Circuit Aorta and branches Pulmonary arteries Left atrium
Pulmonary veins
Right atrium
Heart
Right ventricle
Left ventricle
Systemic Circuit
Venae cavae
Oxygen-rich, CO2-poor blood
Oxygen-poor, CO2-rich blood 3

4. II. Location and Orientation within the Thorax
A. Healthy heart typically weighs 250–350 grams
B. Largest organ of the mediastinum - located between the lungs
C. Apex lies to the left of the midline
D. Base is the broad posterior surface
E. The Four “Corners”
► Superior right - at costal cartilage of third rib and sternum
► Inferior right - at costal cartilage of sixth rib lateral to sternum
► Superior left - at costal cartilage of second rib lateral to sternum
► Inferior left - lies in the fifth intercostal space 4

5. 5 Superior vena cava Midsternal line Aorta Rib 2 Parietal pleura (cut)
Diaphragm
Pulmonary trunk
Left lung
Pericardium (cut)
Mediastinum
Apex of heart
Heart
Diaphragm
Right lung T8
Posterior
Mediastinum
Aorta
Superior vena cava
Left lung
Fat in epicardium
Right auricle of right atrium
Rib 5
Right ventricle
Pericardium (cut)
Apex of heart 5

6. III. Membranes of the Heart
Pericardium - two primary layers
A. fibrous pericardium - strong layer of dense connective tissue
B. serous pericardium – reduces friction as heart beats
1. parietal layer = attached to the “wall” of cavity
2. visceral layer = attached to the heart surface (“organ”) 6

7. Parietal layer of serous pericardium
Pulmonary trunk
Fibrous pericardium
Parietal layer of serous pericardium
Pericardium
Pericardial cavity
Myocardium
Epicardium (visceral layer of serous pericardium)
Heart wall
Myocardium
Endocardium
Heart chamber 7

8. IV. Layers of the Heart Wall
A. Epicardium - visceral layer of the serous pericardium (“upon”)
B. Myocardium - consists of cardiac muscle
1. cardiac muscle arranged in circular and spiral patterns
C. Endocardium – inner surface
1. endothelium resting on a layer of connective tissue
2. lines the internal walls of the heart
3. Continuous with endothelium of arteries and veins 8

9. Cardiac muscle bundles9

10. V. Heart Chambers A. Right and left atria - superior chambers
B. Right and left ventricles - inferior chambers
C. Internal divisions – septum wall between chambers
1. interventricular septa
2. interatrial septa 10

11. Auricle of left atrium
Right atrium
Left ventricle
Right ventricle
Apex
Anterior view 11

12. VI. Right Atrium A. Forms right border of heart
B. Receives oxygen-poor blood from systemic circuit through:
1. superior vena cava
2. inferior vena cava
3. coronary sinus (blood returning from veins of heart itself)
C. Pectinate muscles - ridges inside anterior of right atrium
D. Fossa ovalis - depression in interatrial septum
1. remnant of foramen ovale – hole between atria in fetal heart 12

13. VII. Right Ventricle
A. Receives blood from right atrium through the right atrioventricular valve (tricuspid valve)
B. Pumps blood into pulmonary circuit through pulmonary trunk
C. Features of the internal walls of right ventricle
► trabeculae carneae – “fishnet like” small cavities
► chordae tendineae – “strings” attached to the valve cusps
► papillary muscles – attached to the chordae
► pectinate muscle – normal “smooth-like” muscle of walls
D. Pulmonary semilunar valve (pulmonary valve)
1. Located at opening of right ventricle and pulmonary trunk 13

14. VIII. Left Atrium A. Forms the apex of the heart
B. Makes up heart’s posterior surface
C. Receives oxygen-rich blood from lungs through pulmonary veins
D. Opens into the left ventricle through
1. left atrioventricular valve (bicuspid valve)
a. mitral valve is another name for the left AV valve
E. Pumps blood through systemic circuit via
1. aortic semilunar valve (aortic valve) 14

15. Brachiocephalic trunk
Superior vena cava
Right pulmonary artery
Ascending aorta
Pulmonary trunk
Right pulmonary veins
Right atrium
Right ventricle
Inferior vena cava
Anterior view 15

16. Anterior view 16

17. Left common carotid artery
Left subclavian artery
Aortic arch
Left pulmonary artery
Left pulmonary veins
Auricle of left atrium
Left ventricle
Apex
Anterior view 17

18. Anterior view 18

19. Right atrium Right ventricle Fossa ovalis Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Frontal section 19

20. Frontal section 20

21. Left atrium Left ventricle Left pulmonary veins
Mitral (bicuspid) valve
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Frontal section 21

22. Frontal section 22

23. Inferior view; surface shown rests on the diaphragm.
Auricle of left atrium
Right atrium
Left atrium
Left ventricle
Right ventricle
Apex
Inferior view; surface shown rests on the diaphragm. 23

24. IX. Heart Valves—Valve Structure
A. Atrioventricular (AV) valves
1. between atria and ventricles
Right AV valve  tricuspid valve
Left AV valve  bicuspid (mitral) valve
B. Aortic and pulmonary valves
1. at junction of ventricles and great arteries 24

25. Mitral (left atrioventricular) valve
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Mitral (left atrioventricular) valve
Tricuspid (right atrioventricular) valve
Aortic valve
Pulmonary valve
Anterior 25

26. 26 Direction of blood flow Atrium
Cusp of atrioventricular valve (open)
Chordae tendineae
Papillary muscle
Ventricle 26

27. X. Pathway of Blood Through the Heart
superior/inferior vena cavae ►
right atrium ►
(tricsupid valve) ►
right ventricle ►
(pulmonary semilunar valve) ►
pulmonary trunk ►
LUNGS ► pulmonary veins ►
left atrium ►
(bicuspid (mitral) valve) ►
left ventricle ►
(aortic semilunar valve) ►
aorta ► BODY 27

28. 28

29. XI. Structure of Heart Wall
A. Walls differ in thickness
1. atria = thin walls; ventricles = thick walls
2. left ventricle 3X thicker than right ventricle
a. exerts more pumping force (to the body!!)
Left venticle 29

30. XII. Conduction System of the Heart
A. Cardiac muscle cells have intrinsic ability to:
1. generate and conduct impulses
2. signal these cells to contract rhythmically
SA node ►
AV node ►
AV Bundle (Bundle of His) ►
Bundle branches ►
Purkinje fibers 30

31. Inter- ventricular septum
Right atrium
sinoatrial (SA) node (pacemaker cells)
atrioventricular (AV) node
Left atrium
atrioventricular (AV) bundle
Inter- ventricular septum
bundle branches
Purkinje fibers 31

32. Inter- ventricular septum
Right atrium
Left atrium
Inter- ventricular septum 32

33. XIII. Innervation of the Heart
A. Parasympathetic fibers 1. branches of vagus nerve (X) 2. decrease heart rate 3. restricted to: SA node, AV node, coronary arteries B. Sympathetic nerves 1. travel from cervical and upper thoracic chain ganglia 2. also SA node, AV node, coronary arteries 3. also innervate cardiac muscle throughout the heart a. increase heart rate and strength of contraction

34. 34 Dorsal motor nucleus of vagus
The vagus nerve (parasympathetic) decreases heart rate.
Cardioinhibitory center
Cardioacceleratory center
Medulla oblongata
Sympathetic trunk ganglion
Thoracic spinal cord
Sympathetic trunk
Sympathetic cardiac nerves increase heart rate and force of contraction.
AV node
SA node
Parasympathetic fibers
Sympathetic fibers
Interneurons 34

35. XIV. Blood Supply to the Heart
A. Coronary arteries 1. right coronary artery ► branches to form the marginal artery ► later branches into the posterior interventricular artery 2. left coronary artery ► anterior interventricular artery and circumflex artery

36. XV. Cardiac Veins
A. carry deoxygenated blood from the heart wall to the right atrium B. occupy sulci (grooves) on the heart’s surface C. Coronary sinus—runs in the posterior part of the coronary sulcus 1. Returns majority of venous blood from heart to the right atrium D. Three tributaries of coronary sinus ► great cardiac vein ► middle cardiac vein ► small cardiac vein

37. Anastomosis (junction of vessels) Left atrium
Superior vena cava
Aorta
Pulmonary trunk
Anastomosis (junction of vessels)
Left atrium
Left coronary artery
Right atrium
Right coronary artery
Circumflex artery
Left ventricle
Right ventricle
Anterior interventricular artery
Right marginal artery
Posterior interventricular artery
The major coronary arteries
Superior vena cava
Anterior cardiac veins
Great cardiac vein
Coronary sinus
Small cardiac vein
Middle cardiac vein
The major cardiac veins 37