me007
Forum Guru
Topics: 72
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b.
osmotic effect -dehydration of swollen tissue.
(along with osmotic diuresis)
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| epica
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Sorry, try again
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| epica
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It's not simple Q, try again.
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| me007
Forum Guru
Topics: 72
Posts: 803
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mannitol is osmotically active substance.
will increase blood oncotic pressure. By this water content in ECF will decr - decr swelling
I remember that constriction of cerebral arterioles is important and it managed by hyperventilation -decreasing pt's PCO2, what constrict brain arterioles
But how mannitol would constrict arterioles i don't know.
Blood viscosity vs blood osmolarity - might be that -e?
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| epica
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Ans is A
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| new_n_lost
Politically InCorrect
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There is no proof that osmotic agents such as mannitol lower intracranial pressure (ICP) by decreasing brain water content. An alternative mechanism might be a reduction in cerebral blood volume through vasoconstriction. Mannitol, by decreasing blood viscosity, would tend to enhance cerebral blood flow (CBF), but the cerebral vessels would constrict to keep CBF relatively constant, analogous to pressure autoregulation
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| new_n_lost
Politically InCorrect
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Honestly Speaking i was always under the impression that Mannitol removes water from tissues n that also applies to the brain this is an Eye Opener.
Epica CAn u plz post the Explanation to the Question. that wud be certainly helpful.
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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| me007
Forum Guru
Topics: 72
Posts: 803
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from Katzung.
osmotic diuresis alter Starling forses so that water leaves cells and reduce intracellular volume.
This effect is used to reduce intracranial pressure.
Can't belive that A is correct ans.
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| epica
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BELIEVE, it's correct, It's already explained
You can do additional search in PubMed, but NNL already explained
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| po
Forum Elite
Topics: 39
Posts: 356
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just a doubt,mannitol causes diuresis...reduces blood volume...so should increase viscosity??
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| epica
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Please see nnl post, he already explained
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| shalini.ravi
Forum Senior
Topics: 17
Posts: 153
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good q epica !!! but i still hvnt completely understood the explanation,how is the blood viscocity decreasin nnl? well i'll remember that there's vasoconstiction but its still vague  can anyone explain? am a bit slow ,sorry abt that
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| epica
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Please read my post above.
I gave exact explan. I can not add more.
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