Term
| which organs use the most oxygen? |
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Definition
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Term
| what are the three mechanisms for controlling local blood flow? |
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Definition
metabolic regulation
autoregulation
sheer stress induced vasodilation |
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Term
| define active / reactive hyperemia. |
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Definition
active - increase in blood flow to a region due to increased metabolite production
reactive - increased blood flow to an area due to oxygen debt after a pause in flow |
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Term
| describe the metabolic mechanism for increasing blood flow to an area. |
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Definition
| metabolites cause proportional vasodilation at the precapillary bed to remove the increased metabolites |
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Term
| describe the role of autoregulation of blood flow as it relates with changes in perfusion pressure. |
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Definition
| the body has a set blood flow, and changes in perfusion pressure (such as IV infusion) cause rapid changes in flow. the body adjusts to return the flow back to normal despite the change in pressure. this is because the body was already in a flow equilibrium |
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Term
| define transmural pressure. |
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Definition
| the difference in pressure inside and outside a wall. |
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Term
| define the myogenic hypothesis and how does it relate to changes in transmural pressure? |
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Definition
it states that an increase in tension on smooth muscle causes it to contract, and a decrease in tension causes it to relax
an increase in the transmural pressure due to an increase in flow causes the smooth muscle to constrict and therefore reduce vessel diameter |
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Term
| is myogenic regulation endothelium dependent or independent and why? |
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Definition
| independent, because it is caused by the stretch of the smooth muscle regardless of the presence of the endothelium |
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Term
| what causes the myogenic regulatory response? |
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Definition
| the stretch of the muscle cells cause changes in the conductance of the ion channels which leads to depolarization and contraction |
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Term
| describe shear stress induced vasodilation and how is it caused? |
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Definition
| it is an endothelium dependent mechanism in which an increase in flow causes vasodilation due to increased NO production, this mechanism is regardless of pressure |
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Term
| how does exercise affect upstream vessel diameter? |
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Definition
| increased metabolite production causes downstream vasodilation, this in turn causes an increase in flow up and downstream. the increased flow upstream leads to an increase in sheer stress which then causes upstream vasodilation in order to support more flow to the exercising muscle |
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Term
| what organs are predominantly under metabolic control? |
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Definition
| brain, heart, skeletal muscles |
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Term
| what organs are predominantly under sympathetic/neurogenic control? |
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Definition
| skin, kidney, splanchnic organs |
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Term
| at the sympathetic neuro-effector junction what determines the type of response? |
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Definition
| the receptor and not the neurotransmitter |
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Term
| what type of vascular response is caused by alpha 1 and 2 receptors and why? |
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Definition
| they cause vasoconstriction due to an increase in intracellular Ca |
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Term
| what type of vascular response is caused by beta 1 receptors and why? |
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Definition
| they cause vasoconstriction due to an increase in intracellular Ca, and they increase cardiac contractility and HR |
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Term
| what type of vascular response is caused by beta 2 receptors and why? |
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Definition
| they cause vasodilation due to a decrease in intracellular Ca |
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Term
| describe the difference between receptor affinities of epinephrine and norepinephrine. |
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Definition
| epi can bind all three receptors, but binds strongest to beta 2 receptors, and NE only binds to alpha 1 and beta 1 receptors |
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Term
| what is the main difference between smooth muscle cell receptors and neuronal cell receptors? |
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Definition
| smooth muscle cells have muscarinic acid receptors for Ach, whereas neuronal cells have nicatinic acid receptors |
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Term
| what affect does acetylcholine have on the heart? |
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Definition
| it causes a decrease in HR and conduction velocity |
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Term
| what affect does acetylcholine have on the blood vessels and where is this affect seen? |
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Definition
| it causes vasodilation, but is only seen in the distal end of the colon and genitals due to their innervation by the parasympathetic nervous system |
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