CIRCULATORY SYSTEM FUNCTION OF THE HEART

Four Main Functions of the Circulatory System Pump ___________ is the pump that circulates blood to all parts of the body Blood transport system around body Arteries, veins, and capillaries are the structures that take blood from the heart Carries oxygen and nutrients to cells, carries away waste products Lymph system Returns excess tissue fluid to general circulation

Heart (see figure 13-2 pg. 262) Avg. 72 bpm, 100,000 beats per day Superior and inferior vena cava bring deoxygenated blood to the ________ atrium Cardiopulmonary circulation Circulation form the heart to the ________. Pulmonary artery Takes blood from the right ________ to the lungs Pulmonary veins Bring _______ blood from the lungs to the left atrium Aorta Takes blood from the left ventricle to the rest of the body Four heart valves which are:

Pump Heart is a double pump Which means what? Now look at the board for the order circulation Also see figure 13-5 pg. 266

Heart Sounds “Lubb dupp” sound Comes from the valves closing Lubb sound is heard 1st and made by tricuspid and bicuspid closing (S1 sound) Loudest at the apex Dupp sound is heard 2nd and is shorter and higher pitched (S2 sound) Caused by the semilunar and pulmonary valves closing

Electrical Activity SA (sinoatrial) node Pacemaker Sends out electrical impulses, spreads impulse over the atria and makes them contract AV (atrioventricular) node Carries impulse to Bundle of His Located b/t the atria and ventricle Bundle of His Conducting fivers in septum Divides into left and right branches in ventricles to Purkunje fibers Purkunje fibers Cause ventricles to contract

Cardiac Cycle 1 (see figure 13-6 pg. 268) SA node>stimulates both artia>blood flows from atria to ventricles via tricuspid and bicuspid valves At same time ventricles are relaxed allowing them to fill with blood = seminular valves closed so blood cannot enter pulmonary artery or aorta

Cardiac Cycle 2 AV node>stimulates contraction of both ventricles>blood pumped into the pulmonary artery and aorta Atria are relaxed and tricuspid and bicuspid valves close

Cardiac Cycle 3 Ventricles relax>semilunar valves close>heart rests briefly (repolarization) Cycle then begins again with the signal from the SA node Each cardiac cycle takes 0.8 seconds and represents one heart beat