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30 Cards in this Set

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What determines resistance to local flow?
Arteriolar diameter
There is a basal degree of vascular SM contraction(at rest)
True
Vascular tone allow both increases and decreases in resistance and therefore flow.
True
Cells tell arterioles they need more blood,so they
Dilate
What are the 2 responses intrinsic to an artery regarding vascular SM contraction?
-Myogenic response to stretch
-Endothelium-dependent response to flow.
Spontaneous depol. leads to APs that produce basal tone in cells of arteries.
True(mechanical and chemical factors can modify that)
What is autoregulation?
Mechanism which ensures constant flow despite a wide range of perfusion pressures w/o need for nervous or hormonal input.----> protects cells from fluctuations in BP.
What is autoregulation built around?
Myogenic response
What can be said about myogenic response?
It preserves organ flow in face of changing arterial pressure and is most obvious in arterioles.
Myogenic response maintains capillary hydrostatic pressures against
Postural changes in pressure.
Myogenic response involves the endothelium
False.
Who are the stretch receptors?
Na+ channels
WHat does the stretch do?
Deform the protein channels that allow Na+ in.
WHat constitutes the myogenic response?
Stretch-induced increase in vascular SM contraction and stretch-activated non-selective cation channels.
What can be said about the endothelium?
Adjacent to SM and separates SM from blood.(endothelium communicates constantly with SM)
What does the endothelium produce?
Substances that alter SM contraction-NO for SM relax.
-endothelim for SM contractio.
-Prostaglandins.
Endotheium mediates actions of circulating substances.
True-Angiotensin,Thrombin,bradykinin.
How do we get NO?
Produced by endothelial NO synthase from l-arginine.
What stimulates NO ?
Physical stimuli like shear stress.
Does hypoxia stimulate NO production?
Yes.
Name some other susbtances that stimulate NO production.
Bradykinin,ATP,ADP,histamine.
What is the function of NO ?
-Increases SM cGMP
-Reduced intracellular Ca2+
-Causes SM relaxation
Can white cells cause vasodilation?
True(NO,histamine,cytokines)
Platelets cause vasoconstriction via
Thrombin and ADP
Adrenaline constricts most arteries in the body except
in Muscles and Heart.(epi. in early phase of exercise cause muscles to dilate)
WHat do Angiotensin 2,epi and ADH have in common?
Reduce blood flow to organs by constricting arterioles.
What do symp NS release?
Noradrenaline
What does norad. do?
Constricts blood vessels by activating alpha-adrenergic receptors.
Sympathetic tone
constricts vessels at rest.
Integrated response depends on:
-nature and no. of specific receptors
-local metabolic signals
-hormonal and neural signals.