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19 Cards in this Set
- Front
- Back
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What is achieved by unilateral carotic occlusion?
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Decreased carotid sinus pressure which prompts a responsive increase in MAP
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How does carotic occlusion cause an increased MAP?
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-Decreased rate of firing caused by decreased stretch of stretch receptors
-Decreased PNS output; increased SNS output -> incr HR/contractility and circulatory vasoconstriction. |
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3 Effects of increased SNS:
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1. increased HR
2. increased contractility 3. increased TPR |
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Why doesn't unilateral carotic occlusion increase MAP as much as bilateral?
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Because buffering is achieved by the remaining carotid sinus and the aortic baroreceptors.
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What happens when the unilateral occlusion is released?
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Undershoot and overshoot of MAP due to a percieved increased pressure in the carotid sinuses.
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Why doesn't MAP decrease in response to the increased CO when people exercise?
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Because the baroreceptors reset themselves.
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How is a bilateral carotid sinus occlusion different from unilateral?
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The increase in MAP will be bigger and oscillation after release may be larger.
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What happens when you occlude IVC and SVC?
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-Decrease venous return
-Decr preload -> contractility -Decrease MAP |
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What is the baroreceptor response to IVC/SVC occlusion?
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Detects decreased MAP so decreases firing; reduces PNS outflow and increases SNS outflow to bring MAP back up
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What happens when IVC/SVC occlusion is released?
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All of a sudden VR increases again; filling of heart increases contractility, SV, BP.
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What happens when the Aorta is occluded?
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-Afterload acutely increased
-BP below occlusion decreases -BP before occlusn increases |
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What is the response to BP changes after aortic occlusion?
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The aortic baroreceptors just before the occlusion see an increased BP so they decrease SNS and increase PNS
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Results of Aortic occlusion effects on circulation:
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-Vasodilation
-Decreased HR -Decreased contractility |
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How is nonneural effect of aortic occlusion different from neural?
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The neural decrease in heart contractility is masked by the decreased ejection fraction which causes increased stroke volume so incr contractility.
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Why does the aortic pressure waveform have a characteristic appearance?
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Because the pressure values and wave configurations are altered during transmission thru the arterial tree.
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What happens to the aortic pressure waveform with increasing distance from the aorta?
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1. Dicrotic notch lessons and waves may appear in it.
2. Pulse pressure increases |
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Why does pulse pressure increase w/ distance form the aorta?
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Because pulse waves summate
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Why may waves develop in the dicrotic notch of aortic pressure waveform?
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Because of resonant oscillations in the elastic arteries caused by the ejected volume bolus.
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What is the effect of a sudden 50 mL injection of volume?
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-Suddenly VR increases
-EDV increased - so increased contractility, stroke volume, and MAP. |
