physio question

Started by oompaAPD
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oompaAPD

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Just reviewing a little physio before i start my CA-1 year. couldnt find the answer to this one
How long can various organs last without oxygen/blood flow (brain, heart, kidneys, liver, bowel, skeletal muscle, lungs)

Also, when pt is in shock and BP drops, alpha-1 receptors are stimulated and arterioles are constricted, shunting blood from kidneys, liver, etc to brain and heart. Are there any other organs that do not sacrafice blood flow during shock? How is the brain able to selectively receive blood flow? Are the alpha-1 receptors missing in the arterioles to the brain?

thanks to all that reply
 
If I recall corectly blood flow to the brain is largley controlled by Co2 levles or the H+ ion, not by A1 receptors, this is the reason for hyperventilaqtion in head cases, as for how long each organ can last I suspect that this a highley individual thing, an aneroboc patient (JOKE) or severe copd'er may tolerate longer periods ofO2 deprivation because they live there.
 
ATP levels in the brain will drop to zero in roughly seven minutes in a completely anoxic state.

Also, remember that when someone is declared clinically dead that the overwhelming majority of cells in the body are still alive and remain so for an extended period of time.

In the brain specifically, b-1 adrenergic stimulation results in vasodilatation, whereas a-2 adrenergic stimulation causes vasoconstriction and the CO2 response will only be short term (6-8 hours).
 
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