CHAPTER 18 The Cardiovascular System: The Heart: Part B

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

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

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

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

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

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

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

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

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

(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

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

(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

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

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

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

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

(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

(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

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

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

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

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

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

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

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