1. The Circulatory System
“The Heart and Blood Vessels”

2. Location of the Heart
The heart is a 4 - chambered muscle that pumps blood through a closed circulatory system
2/3 of the heart lies to the left of the midline of the body
The apex lies on the diaphragm and the upper border (base) just below the second rib

3. Anterior View

4. Posterior View

5. Coverings of the Heart
Pericardium is the tough sac that surrounds the heart.
Fibrous pericardium- tough inelastic sac around the heart.
Serous pericardium-consists of parietal layer (outside) and visceral layer (touches the heart).
Pericardial space is filled with lubricating (pericardial) fluid.

6. 3 Layers of the Heart
Epicardium- same as the visceral layer of the pericardium
Myocardium- thick contractile cardiac muscle cells. The cells are tightly joined together to form a syncytium which transmits action potentials seamlessly.
Endocardium- thin layer that covers muscular projections called trabeculae. This tissue’s folds make up the valves. It is also continuous with lining of blood vessels.

7. Chambers of the Heart
Septum separates the chambers
Atria- two upper chambers of heart - “receiving chambers” Veins carry blood into the atria
Ventricles- two lower chambers which have very thick myocardial “pumping chambers”

8. Valves of the Heart Valves permit blood flow in only one direction.
Atrioventricular (cuspid valves) are anchored to papillary muscles through chordae tendineae
Tricuspid valve has three flaps of endothelium and connects right atrium and ventricle
Bicuspid valve (mitral valve) has two flaps and connects left atrium and ventricle
Semilunar Valves have half-moon shaped flaps growing out of lining of blood vessels.
Pulmonary semilunar valve
Aortic semilunar valve

10. Blood Flow Through the Heart
Arteries always carry blood away from heart
Veins always carry blood toward the heart
Superior and inferior vena cavae
Right atrium
Tricuspid valve
Right ventricle
Semilunar pulmonary valve
Pulmonary arteries
Lungs
Pulmonary veins
Left atrium
Mitral valve
Left ventricle
Aortic semilunar valve
Aorta to the rest of the body

11. Blood Supply to the Heart
Coronary Arteries branch off Coronary Veins drain blood into
directly from the aorta. They the right atrium through the
can form anastomoses to coronary sinus.
ensure blood flow.

12. Heart Disorders
Myocardial infarction (heart attack) – when coronary arteries are clogged (by a clot or plaque) and cardiac cells are starved of oxygen (ischemia).
Mitral valve prolapse – mitral valve (bicuspid) flaps extend into atrium causing leaking