ORGANIZATION OF CARDIOVASCULAR SYSTEM 1.HEART 2.BLOOD VESSELS A.ARTERIES B.VEINS 3.CAPILLARIES 1

Lungs Pulmonary capillaries Pulmonary veins Pulmonary circulation arteries Right side of heart Left side of heart Systemic arteries Systemic veins FIGURE 9-1: Pulmonary and systemic circulation in relation to the heart. The circulatory system consists of two separate vascular loops: the pulmonary circulation, which carries blood between the heart and lungs; and the systemic circulation, which carries blood between the heart and organ systems. Systemic circulation Systemic capillaries = O2-rich blood Organ systems = O2-poor blood Fig. 9-1, p. 242 2

MAIN FUNCTIONS OF THE CIRCULATORY SYSTEM Transport and distribute essential substances to the tissues. Remove metabolic byproducts. Adjustment of oxygen and nutrient supply in different physiologic states. Regulation of body temperature. Humoral communication.

Distribution of Blood in the Circulatory System 67% IN THE SYST. VEINS/VENULES 5% IN THE SYSTEMIC CAPILLARIES 11% IN THE SYSTEMIC ARTERIES 5% IN PULMONARY VEINS 3% IN PULMONARY ARTERIES 4% IN PULMONARY CAPILLARIES 5% IN HEART ATRIA/VENTRICLES

Left atrioventricular (AV) valve Right atrium Superior vena cava (from head) Aorta Left pulmonary artery Right pulmonary artery Left pulmonary vein Right pulmonary vein Left atrium Pulmonary semilunar valve Left atrioventricular (AV) valve Right atrium Right atrioventricular (AV) valve Aortic semilunar valve FIGURE 9-2: Blood flow through and pump action of the heart. (a) Blood flow through the heart. Inferior vena cava (from body) Left ventricle Interventricular septum Right ventricle Arrows indicate direction of the blood flow. = O2-rich blood = O2-poor blood Fig. 9-2a, p. 243 5

Interventricular septum Inferior vena cava Aorta Pulmonary artery Superior vena cava Pulmonary valve Pulmonary veins Pulmonary veins Left atrium Left AV valve Right atrium Aortic valve Chordae tendineae Right AV valve Papillary muscle FIGURE 9-4: Heart valves. (a) Longitudinal section of the heart, depicting the location of the four heart valves. Left ventricle Right ventricle Interventricular septum Inferior vena cava Fig. 9-4a, p. 245 6

Pressure Drop in the Vascular System ELASTIC TISSUE MUSCLE LARGE ARTERIES SMALL ARTERIES MEAN PRESSURE ARTERIOLES CAPILLARIES VENULES &VEINS LARGE SMALL LARGE INSIDE DIAMETER 7