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Title: Why does the parasympathetic N.S. try to lower the blood pressure at the same time the sympathetic ... Post by: APL314 on Mar 6, 2017 If someone has a head injury that increases ICP, the sympathetic N.S. raises the blood pressure to pump against the increased resistance created by the ICP. This is necessary to perfuse the brain and maintain life. So why are the baroreceptors signaling for the parasympathetic N.S. to lower the blood pressure??? It seems detrimental to the body to do that.
Title: Re: Why does the parasympathetic N.S. try to lower the blood pressure at the same time the ... Post by: Othello2 on Mar 7, 2017 ICP is intracranial pressure. So yes you are right the symp system has to increase pressure to overcome in increase in ICP to perfuse the brain which is good right? well yes and now. Yes because your brain needs oxygen, but bad because increasing blood pressure will increase the pressure within the brain. The parasymp system reads this increase in pressure and tries to dampen the heart, which is also detrimental since your brain isn't getting enough oxygen.
Basically your body doesn't really know how to react, and basically both systems are hurting the brain.. symp system is increasing ICP but the parasymp is limiting perfusion. But both are fighting each other which is why portions of skull are often removed to release the pressure. |