The Cardiovascular System The Heart 20-1

FUNCTIONS OF THE HEART Generating blood pressure Routing blood Heart separates pulmonary and systemic circulations Ensuring one-way blood flow Heart valves ensure one-way flow Regulating blood supply Changes in contraction rate and force match blood delivery to changing metabolic needs 20-2

SIZE, SHAPE, LOCATION OF THE HEART Size of a closed fist Shape Apex: Blunt rounded point of cone Base: Flat part at opposite of end of cone Located in thoracic cavity 20-3

HEART CROSS SECTION 20-4

HEART WALL Three layers of tissue Epicardium: This serous membrane of smooth outer surface of heart Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contracting Endocardium: Smooth inner surface of heart chambers 20-5

HEART WALL LAYERS 20-6

HEART WALL LAYERS 20-7

EXTERNAL ANATOMY Four chambers 2 atria 2 ventricles Auricles a small, muscular pouch at the upper corner of the atrium Major veins Superior vena cava Pulmonary veins Major arteries Aorta Pulmonary trunk 20-8

EXTERNAL ANATOMY 20-9

HEART VALVES Atrioventricular Tricuspid Bicuspid or mitral Semilunar Aortic Pulmonary Prevent blood from flowing back 20-10

HEART VALVES 20-11

FUNCTION OF THE HEART VALVES 20-12

BLOOD FLOW THROUGH HEART 20-13

INTERACTIVE HEART Go to: And use the inteactive explorer to practice your knowledge of the heart.