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Physio Ch. 15, Blood Flow and BP

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hrdcorhrvivor's version from 2017-04-18 05:29

Section 1

Question Answer
elastic arteriesexpansion and recoil to maintain bp, recoil drives blood through diastolic phase
muscular arteriesthick tunica media, little change in diameter with bp, increased resistance to blood flow due to smaller lumen
arteriolessmallest arteries, control blood flow into capillaries with precapillary sphincters
physics of flowphysical laws govern blood flow through vessels, pressure gradients drive flow, resistance impedes flow
pressure gradientsmovement of blood occurs due to these
pressure differentialsgreatest loss of pressure across muscular arteries and arterioles
resistance (R)directly proportional to length of vessel (L) and viscosity of blood (n) indirectly proportional to radius of vessel (r)
decrease in r causes?increased R leading to increased bp
blood flow (F)directly proportional to pressure gradients and r, indirectly proportional to R
regulation of blood flowdepended on r, regulated by extrinsic neuroendocrine, paracrine, intrinsic myogenis and metabolic
extrinsic regulationANS controls blood flow through SNS and PSNS. SNS: alpha adrenergic: vasoconstriction and basal tone, cholinergic in skeletal muscle: vasodilation. PSNS: always cholinergic, always vasodilation, Gi tract, genitalia, salivary glands
paracrine regulationNO, bradykinin, prostacyclin produced by endothelium: vasodilators. endothelin-1:vasocontsrictor
intrinsic regulationmyogenic: auto regulatory mechanism used by brain and kidneys. metabolic: uses conc. of o2 and co2, low ph, release of k+ and ATP to vasodilate
hyperemiareddening of the skin. reactive: blood flow has been restricted from an area, metabolites built up. active: increase blood flow to skel musc when it undergoes increased metabolism
BP and pulsehigh in arteries, low in veins. systolic: pressure during vent systole 120, diastolic: pressure during vent diastole 80.
mean arterial pressureinfluenced by cardiac output and total peripheral resistance. map=diastolic bp+1.3 pulse pressure
blood is returned to the heart in 3 ways1. skeletal musc pump 2. respiratory pump 3. cardiac suction
pulserapid increase in pressure when left vent pushes into aorta
pulse pressure=systolic bp-diastolic bp
map relationship to co and tprF into aorta is equal to CO of left vent, F out of arteries influenced by tpr, map proportional to co x tpr, increase in co or tpr is increase in map
baroreceptor reflexprimary pathway for map control, mechanoreceptors sensitive to stress, aorta:monitors pressure to body. carotid arteries: monitors pressure to brain. send signals to CVCC
baroreceptor reflex proportions to bpincreased bp: increased APs to CVCC, increased PSNS and decreased SNS activity, decreased HR and BP
memorize

Section 2

Question Answer
hypertensionincreased bp 140/90 or higher, causes baroreceptors to adapt to high pressure, CVCC interprets this as new normal
orthostatic hypotensionlaying flat blood evenly distributed, standing causes blood to pool in lower extremities, leads to instant drop in venous return
vasovagal syncopetriggered by sight of blood or needles, leads to increase in PSNS activity decrease in SNS, systemic vasodilation and decreased HR
bulk flowmass movement of fluid due to hydrostatic pressure or osmotic pressure gradients. absorption: fluid into capillaries, filtration: fluid out of capillaries
starling forcesfluid movement is dependent on hydrostatic pressure and oncotic pressure. hydro: decreases along capillary length. oncotic: colloid osmotic, created by proteins in blood plasma
net pressuredriving fluid flow determined between hydrostatic and oncotic pressure. if np > 0: filtration favored. np <0: absorption favored np= no net flow
plasma flow on arterial endP-H is high 32 mmHg, oncotic pressure constant at 25 mmHg, filtration occurs
plasma flow on venous endP-H is low 15 mmHg, oncotic pressure constant at 25 mmHg, absorption occurs
memorize

Section 3

Question Answer
lymphatic system functions1. returning fluids and proteins back to circulation 2. picking up fat absorbed from small intestine 3. capture and destroy pathogens
lymph vessels one way flow from IF in tissues back to cirulation
edemaaccumulation of fluid in IF, two causes: inadequate drainage of lymph (elephantiasis), capillary filtration exceeds absorption
increase in capillary hydrostatic pressureindicative of increased venous pressure, common cause: heart failure
decrease in concentration of plasma proteinsdecreses oncotic pressure, increases filtration, causes: severe malnutrition or liver failure,
increase in intersitial proteinsdecreases oncotic pressure, increases filtration, cause: inflammation
memorize