Functional Model of the Cardiovascular System Figure 15-1

Figure 15-2 Blood Vessel Structure

Figure 15-3 MIcrocirculation Capillaries lack smooth muscle and elastic tissue reinforcement which facilitates exchange

Figure 15-4a, step 1 Elastic Recoil in Arteries (a)Ventricular contraction Ventricle contracts. Arterioles 1 1

Figure 15-4a, steps 1–2 Elastic Recoil in Arteries (a)Ventricular contraction Ventricle contracts.Semilunar valve opens. Arterioles

Figure 15-4a, steps 1–3 Elastic Recoil in Arteries (a)Ventricular contraction Ventricle contracts. Aorta and arteries expand and store pressure in elastic walls. Semilunar valve opens. Arterioles

Figure 15-4b, step 1 Elastic Recoil in Arteries (b)Ventricular relaxation Isovolumic ventricular relaxation occurs. 1 1

Figure 15-4b, steps 1–2 Elastic Recoil in Arteries (b)Ventricular relaxation Isovolumic ventricular relaxation occurs. Semilunar valve shuts, preventing flow back into ventricle

Figure 15-4b, steps 1–3 Elastic Recoil in Arteries (b)Ventricular relaxation Isovolumic ventricular relaxation occurs. Elastic recoil of arteries sends blood forward into rest of circulatory system. Semilunar valve shuts, preventing flow back into ventricle

Review of Blood Flow

Figure 15-5 Pressure throughout the Systemic Circulation Blood pressure is highest in the arteries and decreases continuously as it flows through the circulatory system

Blood Pressure  Pulse Pressure = systolic P – diastolic P  Valves ensure one-way flow in veins  MAP = diastolic P + 1/3(systolic P – diastolic P)

Figure 15-7 Measurement of Arterial Blood Pressure

Figure 15-8 Blood Pressure Mean arterial pressure is a function of cardiac output and resistance in the arterioles

Figure 15-9 Blood Pressure Blood pressure control involves both the cardiovascular system and the renal system

Figure Factors that Influence Mean Arterial Pressure

Arteriolar Resistance  Sympathetic reflexes  Local control of arteriolar resistance  Hormones

Arteriolar Resistance

 Myogenic autoregulation  Paracrines  Active hyperemia  Sympathetic control  SNS: norepinephrine  Adrenal medulla: epinephrine

Hyperemia Figure 15-11a

Figure Norepinephrine Tonic control of arteriolar diameter

Figure Distribution of Blood Distribution of blood in the body at rest

Figure 15-14a Blood Flow Blood flow through individual blood vessels is determined by vessel’s resistance to flow

Figure 15-14b Blood Flow Blood flow through individual blood vessels is determined by vessel’s resistance to flow Flow  1/resistance

Figure 15-18a Fluid Exchange at a Capillary Hydrostatic pressure and osmotic pressure regulate bulk flow Animation: Cardiovascular System: Autoregulation and Capillary Dynamics PLAY

Figure Medullary cardiovascular control center Carotid and aortic baroreceptors Change in blood pressure Parasympathetic neurons Sympathetic neurons Veins Arterioles Ventricles SA node Integrating center Stimulus Efferent pathway Effector Sensor/receptor KEY Blood Pressure Components of the baroreceptor reflex

Figure The baroreceptor reflex: the response to increased blood pressure

Figure The baroreceptor reflex: the response to orthostatic hypotension

Figure Hypertension The relationship between blood pressure and the risk of developing cardiovascular disease Essential hypertension has no clear cause other than hereditary

Hypertension  Carotid and aortic baroreceptors adapt  Risk factor for atherosclerosis  Heart muscle hypertrophies  Pulmonary edema  Congestive heart failure  Treatment  Calcium channel blockers, diuretics, beta-blocking drugs, and ACE inhibitors