1. CHAPTER 18
The Cardiovascular System: The Heart: Part B

2. Learning Objectives
At the end of the discussion students should be able to :
Recognize the pathway of the blood through the heart
Name and recognize the coronary circulation of the heart
Identify and enlist the types of the heart valves
Explain the development of the heart

3. Lecture Outline Pathway of Blood Coronary circulation Heart valves
Development of the heart

4. Pathway of Blood Through the Heart
The heart is two side-by-side pumps
Right side is the pump for the pulmonary circuit
Vessels that carry blood to and from the lungs
Left side is the pump for the systemic circuit
Vessels that carry the blood to and from all body tissues

5. Capillary beds of lungs where gas exchange occurs Pulmonary Circuit
Pulmonary veins
Pulmonary arteries
Aorta and branches
Venae cavae
Left atrium
Left ventricle
Right atrium
Heart
Right ventricle
Systemic
Circuit
Oxygen-rich,
CO2-poor blood
Capillary beds of all
body tissues where
gas exchange occurs
Oxygen-poor,
CO2-rich blood
Figure 18.5

6. Pathway of Blood Through the Heart
Right atrium  tricuspid valve  right ventricle
Right ventricle  pulmonary semilunar valve  pulmonary trunk  pulmonary arteries  lungs

7. Pathway of Blood Through the Heart
Lungs  pulmonary veins  left atrium
Left atrium  bicuspid valve  left ventricle
Left ventricle  aortic semilunar valve  aorta
Aorta  systemic circulation

10. Cardiac muscles need the blood too!!!! It’s a living tissue

11. Coronary Circulation
The functional blood supply to the heart muscle itself
Collateral routes provide additional routes for blood delivery

12. Coronary Circulation Arteries
Right and left coronary (in atrioventricular groove),
Marginal artery
Circumflex artery
Anterior interventricular arteries

13. (a) The major coronary arteries
Left
coronary
artery
Circumflex
artery
Right
coronary
artery
Anterior
interventricular
artery
Right
marginal
artery
Posterior
interventricular
artery
(a) The major coronary arteries
Figure 18.7a

14. Coronary Circulation Veins Small cardiac vein Anterior cardiac vein
Middle cardiac vein
Coronary sinus
Great cardiac vein

15. (b) The major cardiac veins
Superior
vena cava
Great
cardiac
vein
Anterior
cardiac
veins
Coronary
sinus
Small cardiac vein
Middle cardiac vein
(b) The major cardiac veins
Figure 18.7b

16. Right pulmonary artery
Aorta
Superior vena cava
Left pulmonary
artery
Right pulmonary artery
Right pulmonary veins
Right atrium
Great cardiac
vein
Coronary sinus
Left ventricle
Middle cardiac vein
(d) Posterior surface view
Figure 18.4d

17. Heart Valves Types Atrioventricular (AV) valves Semilunar valves
Ensure unidirectional blood flow through the heart
Types
Atrioventricular (AV) valves
Semilunar valves

18. Heart Valves Atrioventricular (AV) valves
Prevent backflow into the atria when ventricles contract
Tricuspid valve (right)
Mitral valve (left)

19. Heart Valves Semilunar (SL) valves
Prevent backflow into the ventricles when ventricles relax
Aortic semilunar valve
Pulmonary semilunar valve

20. (right atrioventricular) valve Area of cutaway
Myocardium
Pulmonary valve
Aortic valve
Tricuspid
(right atrioventricular)
valve
Area of cutaway
Mitral valve
Tricuspid valve
Mitral
(left atrioventricular)
valve
Myocardium
Tricuspid
(right atrioventricular)
valve
Aortic
valve
Mitral
(left atrioventricular)
valve
Pulmonary
valve
Aortic valve
Pulmonary valve
Aortic valve
Pulmonary
valve
Area of cutaway
(b)
Fibrous
skeleton
Mitral valve
Tricuspid valve
(a)
Anterior
Figure 18.8a

21. (right atrioventricular) valve
Myocardium
Tricuspid
(right atrioventricular)
valve
Mitral
(left atrioventricular)
valve
Aortic
valve
Pulmonary
valve
Pulmonary valve
Aortic valve
Area of cutaway
(b)
Mitral valve
Tricuspid valve
Figure 18.8b

22. Opening of inferior vena cava Mitral valve Chordae tendineae
Tricuspid valve
Myocardium
of right
ventricle
Myocardium
of left ventricle
Pulmonary
valve
Aortic valve
Area of
cutaway
Papillary
muscles
Mitral valve
Interventricular
septum
Tricuspid
valve
(d)
Figure 18.8d

23. Developmental Aspects of the Heart
Development of heart occurs from 4th week – 6th week from mesoderm.
Right and left endocardial tubes fuse by Day 22 of development to form heart tube

24. Developmental Aspects of the Heart
Folding and rotation of heart tube results in the formation of cardiac chambers

25. Ductus arteriosus Arterial end Arterial end Aorta 4a Superior vena
cava 4
Pulmonary
trunk
Tubular
heart
Ventricle
Foramen
ovale 3
Atrium 2
Ventricle 1
Inferior
vena cava
Ventricle
Venous end
Venous end
(a) Day 20:
Endothelial
tubes begin
to fuse.
(b) Day 22:
Heart
starts
pumping.
(c) Day 24: Heart
continues to
elongate and
starts to bend.
(d) Day 28: Bending
continues as ventricle
moves caudally and
atrium moves cranially.
(e) Day 35: Bending
is complete.
Figure 18.23

26. KEY POINTS Pathway of Blood
-Right side is the pump for the pulmonary circuit
-Left side is the pump for the systemic circuit
Right atrium  tricuspid valve  right ventricle
Right ventricle  pulmonary semilunar valve  pulmonary trunk  pulmonary arteries  lungs
Lungs  pulmonary veins  left atrium
Left atrium  bicuspid valve  left ventricle
Left ventricle  aortic semilunar valve  aorta
Aorta  systemic circulation

27. KEY POINTS Coronary circulation Heart valves
Arteries – right coronary, left coronary, marginal, circumflex, and anterior interventricular arteries
Veins – small, anterior and great cardiac veins
Heart valves
Atrioventricular (AV) valves – Tricuspid (right)
– Mitral ( left)
Semilunar (SL) valves – Aortic valve
– Pulmonary valve

28. KEY POINTS Development of the heart - Develops from the mesoderm
between 4th -6th week
- Right and left endocardial tubes fuse
- Folding and rotation of heart tube results in the formation of cardiac chambers