Blood Pressure PDF

# Blood Pressure ## Blood Pressure (BP) - Arterioles play role in blood distribution and control of BP - Blood flow to capillaries and BP is controlled by aperture of arterioles - Capillary BP is decreased because they are downstream of high resistance arterioles ...

# Blood Pressure ## Blood Pressure (BP) - Arterioles play role in blood distribution and control of BP - Blood flow to capillaries and BP is controlled by aperture of arterioles - Capillary BP is decreased because they are downstream of high resistance arterioles  ## Blood Pressure (BP) - Capillary BP is also low because of large total cross-sectional area  ## Blood Pressure (BP) - Is controlled mainly by HR, SV, and peripheral resistance - An increase in any of these can result in increased BP - Sympathoadrenal activity raises BP via arteriole vasoconstriction and by increased CO - Kidney plays role in BP by regulating blood volume and thus stroke volume ## Baroreceptor Reflex - Is activated by changes in BP - Which detected by baroreceptors (stretch receptors) located in aortic arch and carotid sinuses - Increase in BP causes walls of these regions to stretch, increasing frequency of APs - Baroreceptors send APs to vasomotor and cardiac control centers in medulla - Is most sensitive to decrease and sudden changes in BP ## Baroreceptor Reflex  ## Atrial Stretch Receptors - Are activated by increased venous return and act to reduce BP - Stimulate reflex tachycardia (slow HR) - Inhibit ADH release and promote secretion of ANP ## Measurement of Blood Pressure - Is via auscultation (to examine by listening) - No sound is heard during laminar flow (normal, quiet, smooth blood flow) - Korotkoff sounds can be heard when sphygmomanometer cuff pressure is greater than diastolic but lower than systolic pressure - Cuff constricts artery creating turbulent flow and noise as blood passes constriction during systole and is blocked during diastole - 1st Korotkoff sound is heard at pressure that blood is 1st able to pass thru cuff; last occurs when can no long hear systole because cuff pressure = diastolic pressure ## Measurement of Blood Pressure (continued) - Blood pressure cuff is inflated above systolic pressure, occluding artery - As cuff pressure is lowered, blood flows only when systolic pressure is above cuff pressure, producing Korotkoff sounds - Sounds are heard until cuff pressure equals diastolic pressure, causing sounds to disappear  ## Pulse Pressure - Pulse pressure = (systolic pressure) - (diastolic pressure) - Mean arterial pressure (MAP) represents average arterial pressure during cardiac cycle - Has to be approximated because period of diastole is longer than period of systole - MAP= diastolic pressure + 1/3 pulse pressure