Cardiovascular System: Regulation of Mean Arterial Pressure

baroreceptor reflexes

change peripheral resistance, heart rate, stroke volume in response to changes in blood pressure; carotid sinus, aortic arch

effects of aging

degenerative changes (arteriosclerosis, atherosclerosis, etc.) increased resistance to blood flow

CNS ischemic response: lack of oxygen causes vasomotor center to become inactive then...

extensive vasodilation follows with associated drop in BP. death in CNS ischemic response lasts longer than a few minutes

atrial natriuretic hormone (ANH) mechanism

from cardiac muscle cells when atrial BP increase --> increase urinary production --> decrease BP and blood volume

CNS ischemic response: neurons of vasomotor center strongly stimulated which...

increases blood flow to brain if vessels are intact but at the same time, decreases oxygenation of blood because blood does not go to lungs

angiotensin-converting enzyme (ACE)

inhibitors for controlling hypertension angiotensinogen --> angiotensin I --> (ACE) --> angiotensin II (active)

fluid shift mechanism

movement of fluid from interstitial space into capillaries with decreased BP to maintain blood volume and vice versa

renin-angiotensin-aldosterone mechanism

renin (kidneys) --> angiotensin I --> angiotensin II --> vasoconstriction --> increase aldosterone (increase Na+ reabsorption) requires angiotensin-converting enzyme (ACE)

long-term regulation of blood pressure

renin-angiotensin-aldosterone mechanism vasopressin (ADH) mechanism atrial natriuretic mechanism fluid shift mechanism stress-relaxation response

central nervous system ischemic response

results from high carbon dioxide or low pH levels in medulla and increases peripheral resistance elevation of BP in response to lack of blood flow to medulla oblongata vasomotor center --> vasoconstriction --> increase systemic BP only works for a few minutes and if blood vessels are intact

chemoreceptor reflexes

sensory receptors sensitive to oxygen, carbon dioxide, and pH levels of blood

adrenal medullary mechanism

stimulation of medulla by sympathetic nerve fibers releases epinephrine and norepinephrine --> increase HR and SV vasoconstriction to skin and viscera

vasopressin (ADH - antidiuretic hormone) mechanism

ADH from post. pit. gland --> vasoconstriction to increase BP and decrease urinary production

stress relaxation response

adjustment of blood vessel smooth muscle to respond to change in blood volume when blood volume suddenly declines and pressure drops, smooth muscles contract and vice versa

short-term regulation of blood pressure

baroreceptor reflexes, chemoreceptor reflexes, central nervous system ischemic response, adrenal medullary mechanism