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CHAPTER 21 Blood Vessels & Circulation 21.1: Blood Vessels • Vessel types from heart & back Structure of Vessel Walls • Tunica intima vs. tunica media vs. tunica externa • Know differences in each vessel wall between arteries & veins (Figure 21-2) Arteries • Vasoconstriction vs. vasodilation • Know differences in elastic arteries, muscular arteries & arterioles • Arteriosclerosis—pg. 712 – 713 Capillaries • Permit gas exchange • Capillary beds join arterioles; empty into venules Veins • Know differences in venules, medium-sized veins & large veins • Function of valves in veins Distribution of Blood • Heart, arteries, capillaries: 30 – 35% of blood volume; venous system contains rest • Capacitance vessels accommodate changes in blood volumes 21.2: Capillary Exchange • Pressure & resistance • Inc. pressure inc. flow • Inc. resistance dec. flow Pressure • Blood pressure (BP) vs. capillary hydrostatic pressure (CHP) vs. venous pressure • For circulation to occur, circulatory pressure must overcome total peripheral resistance Total Peripheral Resistance • Vascular resistance • Length vs. diameter; effects • How blood viscosity & turbulence increase resistance • Pressures in vessels (Figure 21-11) Arterial Blood Pressure • Systolic vs. diastolic pressures • Hypertension vs. hypotension Venous Pressure & Return • Venous return has direct impact on cardiac output • Muscular compression & respiratory pump Capillary Pressure & Exchange • Differences & functions of diffusion & filtration • Hydrostatic pressure forces water out of solution; osmotic pressure draws water into solution 21.3: Cardiovascular Regulation Autoregulation • Vasodilators accelerate blood flow • Know examples Neural Mechanisms • Cardiac centers & vasomotor centers of medulla oblongata • Cardioacceleratory / -inhibitory; control of vasodilation / vasoconstriction • Baroreceptor reflexes • ↑ BP = ↓ CO, vasodilation • ↓ BP = ↑ CO, vasoconstriction • Chemoreceptor reflexes • ↑ CO2 or↓ pH = ↑ CO, ↑ BP, vasoconstriction 21.4: CVS Responses CVS Response to Exercise • How cardiovascular system & body responds to light & heavy exercise • More fit heart = ↑ SV, slower HR • Know benefits of exercise in reducing cardiovascular disease CVS Response to Hemorrhaging • Short-term elevation of BP • ↑ CO, vasoconstriction • Continual blood loss promotes shock • Long-term restoration of blood • Fluid retention, release of EPO Vascular Supply to Special Regions • Blood transferred to brain, heart, & lung tissues 21.5: Pulmonary & Systemic Circulation • Pulmonary circuit vs. systemic circuit • Patterns of blood vessel organization • R & L sides generally identical • Vessels have several names • Several arteries & veins supply organs & tissues 21.6 – 21.7: Pulmonary & Systemic Vessels • Know major blood vessels of pulmonary circuit; general function • Know major blood vessels of systemic circuit; general function • Think vessels learned during cat dissection!