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