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Anatomy
Regulation of blood flow
14
Anatomy
Not Applicable
02/16/2004

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Term
what is the goal to regulate blood flow?
Definition
to maintain homeostasis in blood flow to tissues-not too much, not too little
requires constant adjustments in blood pressure(usually accompanied or accomplished by changes in resistance & changes in blood volume)
Term
what's autoregulation?
Definition
changes in local tissue environment cause changes in blood flow to that region via precapillary sphincters
ex: O2 levels fall & CO2 levels rise in active muscles, cause sphincter to open & more blood flows through capillary bed
Term
what is the regulation at the tissue(capillary bed) level?
Definition
autoregulation
Term
what else does autoregulation assume?
Definition
there is adequate blood flowing to the capillary bed, systemic blood pressure must be maintained via short-term & long-term mechanisms
Term
systemic BP maintained(short-term mechanisms) by
Definition
baroreceptors
Term
what are baroreceptors?
Definition
pressure sensors in carotid artery signal brainstem, which relays signal via autonomic nervous system to change heart rate & artery diameter; good for minute-to-minute control, but can adapt(like touch receptors) to high BP
Term
what's an example of baroreceptors?
Definition
systemic flow to brain decreases as you stand up; baroreceptors signal brainstem, sympathetic nervous system increases heart rate & contractility, & causes peripheral vasoconstriction=results in inc of blood flow to brain
Term
what are venules?
Definition
have no smooth muscle; "leaky" site of fluid & WBC release into tissue
Term
what are veins?
Definition
very little elastin(pressure is low) or smooth muscle(no active vasoconstriction) backflow prevented by:
valves &
skeletal muscle contraction
Term
what causes varicose veins?
Definition
valves leak, pooling of blood causes walls to weaken & dilate
Term
adequate blood supply or flow is needed in?
Definition
tissues
Term
blood flow=?
Definition
difference in pressure/resistance
Term
what's difference in pressure?
Definition
blood pressure-blood flows from high pressure to low pressure
Term
what's resistance?
Definition
force that opposes the movement of blood
-plaque build up
-high red blood cell count
-turbulence(not flowing way should, murmur)
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