Understanding Cardiovascular System: Heart Anatomy and Functions

1. Chapter 15 Cardiovascular System

2. Organs • Heart - begins beating in the 4th week of development. • Pumps 7,000 liters of blood each day. • Contracts 2.5 billion times in a lifetime. • Closed Vessel System • Arteries - carry blood away from the heart. • Veins - carry blood toward the heart. • Capillaries - attach arteries and veins.

3. Function • Circulates blood to every cell in the body and removes waste.

4. The Heart • Location and Size • Size of a man’s fist (14 cm long and 9 cm wide) • Lies within the mediastinum - behind sternum (rests on diaphragm). • 2/3 of the heart is on the left side of the body. • Apex is the lower, left “point” of the heart. • Stethoscope is placed here to count the beats.

5. The Heart • Coverings • Pericardium - sac around the heart - loose-fitting • Fibrous - tough white outer covering, • Serous parietal - smooth lining of the fibrous sac. • Epicardium - covers surface of the heart - smooth • Also called serous visceral pericardium • Pericardial space - area between pericardium and epicardium • Contains fluid - pericardial fluid • Lubricates beating heart • Pericarditis - inflammation of pericardium due to infection - linings stick together, very painful.

6. The Structure of the Heart • The wall of the heart: • Epicardium – reduces friction. • Myocardium – thick contractile middle layer, high in mitochondria. • Endocardium – delicate inner layer.

7. The Structure of the Heart Continued • Cavities • Upper – atria • Lower – ventricles • Larger and thicker walled • Carry heavier pumping burden • Left is thickest – has to pump blood to all parts of the body

8. The Structure of the Heart Continued • Valves and Openings • Blood flows in one direction. • Cuspid valves – between cavities. • Bicuspid (mitral) valve - left cavities. • Tricuspid valve - right cavities. • The semi-lunar valve moves blood out of the heart to the aorta and pulmonary artery. • A murmer is an abnormal sound that identifies the leakage of blood through valves in the wrong direction.

9. The Structure of the Heart Continued • Blood Supply • Ventricles get blood from the right and left coronary arteries. • Atria get blood from the small branch coronary artery. • Anastomosis is branching of the main arteries “detours” • Myocardial infarction - death of the heart muscles due to a clot (heart attack).

10. Blood Vessels • Structure • Outer – fibrous tissue, keeps firm • Middle – muscle, constriction, and dilation. • Inner – endothelium - capillaries

11. Blood Vessels Continued • Function • Transportation of nutrients to cells • Capillaries perform this function • Arteries = distributors arterioles capillaries venules veins • Veins = carry and pool blood

12. Blood Vessels Continued • Main Blood Vessels • ascending aorta • aortic arch • subclavian • common carotid • common iliac Ascending Aorta

13. Blood Vessels Continued

14. Blood Vessels Continued • Portal Circulation • Organs that do not pour blood into inferior vena cava. • Blood sent to the liver by the portal vein.

15. Blood Vessels Continued • Fetal Circulation • Gets oxygen and food from mother, not own lungs and digestive tract. • Additional vessels • Umbilical arteries (2) – carry fetal blood to placenta • Placenta – exchanges oxygen and other substances between mother and fetus • Umbilical vein – returns oxygenated blood to liver of fetus • Foramen ovale – opening between right and left atria bypass lungs, closes with first breath. Shed at birth