drhouse
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what will happen to cerebral blood flow, intra cranial tension, and cerebral venous presser during upward vertical acceleration.
Cerebral blood flow -- ICT -- venous presser
A. increase -- increase -- increase
B. decrease-- decrease-- decrease
C. normal-- decrease -- decrease
D. normal -- increase-- increase
E. normal -- normal -- normal
F. increase -- increase -- decrease
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| silver
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B decrease decrease decrease ??
Edited by silver on 07/12/07 - 04:37 PM
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| P4a99
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| silver
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or C ?
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| drhouse
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yeah silver,
great going.....
wot is yr explanation for C???
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| silver
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because of gravitational pull
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| silver
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this is a good question. where is it from?
btw, what is the expln. you have
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| drhouse
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yeah the exact things are something like this....
Brain, spinal cord, CSF and vessels are encased in rigid bony structure. therefore volume of blood, CSF and brain must remain constant.
now if blood flow increases, more perfusion of fluid leads to increased CSF. these increased intra cranial tension compresses Artery thereby decreasing blood flow.
now here in acceleration against gravity. blood is pulled in leg vessels. decreases cerebral blood flow. simultenously ICT and venous presser also decreases thereby decreasing presser on artery. so blood flow increases to normal.
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| new_n_lost
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Good Concept !!
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| drhouse
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i formated this question based on my understanding....
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| silver
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drhouse,
looking back at this question i think the cerebral blood flow should decrease even if the ICT and venous pressure are no longer exerting their pressure on the artery.
i don't think the cerebral flow will return to normal--it will decrease.
your question encompasses the concepts behind the "G-force" and the linear acceleration aviators experience.
what i know of it, is that if a person is vertically accelerated in the headward direction, known as "+G" (positive G), in this case the blood from the head will drain to the lower parts of the body. and no matter how hard the heart works to pump blood to the head, the blood will nevertheless drain to the lower parts. this is why aviators are made to wear G-suits, which squeezes the legs and abdomen so blood flows to thorax and head.
perhaps what is necessary to know in this question stem is the duration of acceleration. if for a short time then yes, cerebral blood flow will maintain at normal cuz the body tries all it can to maintain cerebral blood pressure which is why initially people are conscious--so then the answer should be C. but if duration is prolonged, then ans. is B.
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| P4a99
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silver ... that made the whole story better ... cuz with out acurate numbers you cant make absolute conclusions ...
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| drhouse
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thanks silver for ur explanation,
i think u r right coz i red it from some good books( forgote the name). in that they mentioned that cerebral blood flow is less compromised. this may mean that blood flow is near normal but not exactly normal.
i dont know much about the duration and what happens as time passes. so probably body may keep it normal for short time but long time may take it tolls and it may not be possible to maintain it for long time..
thanks for the good research
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