Components of Cardiovascular System Exercise Physiology

Organization of Circulatory System Functions ◦Deliver oxygenated blood to muscles; 1900 gals/day ◦Aerate blood in lungs ◦Transport heat to surface ◦Deliver nutrients to tissues ◦Transport hormones

Circulatory System: Valves Heart ChambersTwo Pumps in One Right heart to lungs Left heart to body Right and left atrioventricular valves prevent backflow into atria: tricuspid-right, bicuspid (mitral)-left Right and left semilunar valves prevent backflow into ventricles: pulmonic-right, aortic- left

Circulatory System: Heart

Circulatory System: Myocardium Heart wall composed of 3 layers ◦Epicardium ◦Myocardium ◦Endocardium Differs from skeletal ◦Intercalated discs connect cells to permit electrical transmission ◦Homogenous muscle fibers similar to slow twitch fibers

Circulatory System: Heart 1.Ventricular Diastole Ventricular filling and Atrial contraction A-V valve opens Aortic valve closes 2. Beginning of Ventricular Systole Isovolumetric Ventricular contraction A-V valve closes, Aortic valve closed 3. Ventricular Systole Ventricular ejection A-V valve closed Aortic valve opens 4. Beginning of Diastole Isovolumetric Ventricular relaxation A-V valve closed Aortic valve closes Cardiac Cycle

Circulatory System Vasculature Arteries: highly muscular, elastic Capillaries: thin, porous single layer ◦Capillary branching increases cross section area ◦Flow velocity inversely proportional to area, so broad capillary beds have slow blood flow

Circulatory System Vasculature Veins Thinner walls, less muscular Serve as blood reservoir Venous return facilitated by flaps Active cool-down facilitates blood flow

Blood Pressure Blood Pressure = cardiac output x total peripheral resistance

Blood Pressure at Rest Systolic Blood Pressure: pressure in blood vessel due to surge of blood in aorta and subsequent recoil of aortic wall propagates a wave of pressure through circuit. Diastolic Blood Pressure: pressure in blood vessel during diastole. DBP provides indication of peripheral resistance or ease of flow from “a to c”. Normal systolic BP < _?_ mm Hg and diastolic BP < _?_ mm Hg.

Blood Pressure during Exercise During RHYTHMIC exercise, increase in blood flow and dilation of blood vessels in active muscles cause SBP to __?__ and DBP to __?___. During RESISTIVE exercise, sustained muscular forces compress peripheral arteries causing blood pressure __?__. Upper body exercise has ___ BP than exercise with legs.

Blood Pressure during Recovery A bout of light- to moderate-intensity exercise decreases SBP for up to ___ hrs. Pooling of blood in visceral organs and lower extremities reduces central blood volume which contributes to hypotensive recovery response.

Heart’s Blood Supply Openings for left and right coronary arteries are in aorta just above the aortic valve. Aortic valve flaps close coronary arteries during ejection phase.

Heart’s Blood Supply Myocardial oxygen utilization is 70% to 80% at rest, contrast to 25% other tissues. In vigorous exercise, coronary blood flow increases 4-6x above normal.

Heart’s Blood Supply Impaired coronary blood flow: angina pectoris (chest pain). Rate pressure product: estimate of myocardial work (SBP x HR) Myocardium almost completely aerobic