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  #1  
Old 04-27-2013
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Vascular Intracranial Pressure and Cardiovascular Physiology?

Which of the following will be lower than normal in a patient with an abnormally high intracranial pressure

A. Ventricular contractility
B. Heart rate
C. Mean blood pressure
D. Stroke volume
E. Total peripheral resistance
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Old 04-27-2013
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I think it's B) Heart rate due to Cushing reflex
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Old 04-27-2013
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Certainly B. Heart rate
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Old 04-27-2013
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i would say B too
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Old 04-29-2013
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Can any1 plz explain..
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Old 04-29-2013
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Quote:
Originally Posted by cybron View Post
Can any1 plz explain..

The Cushing reflex is complex and seemingly paradoxical.The reflex begins when some event causes increased intracranial pressure (ICP). Since CSF is located in an area which is surrounded by the skull, increased ICP consequently increases the pressure in the fluid itself. The pressure in the cerebral spinal fluid eventually rises to the point that it meets and gradually exceeds the mean arterial blood pressure (MABP or MAP). When the ICP exceeds the MABP, arterioles located in the brain become compressed. Compression then results in diminished blood supply to the brain, a condition known as cerebral ischemia.

During the increase in ICP, both the sympathetic nervous system and the parasympathetic nervous system are activated. In the first stage of the reflex, sympathetic nervous system stimulation is much greater than parasympathetic stimulation.The sympathetic response activates Alpha-1 adrenergic receptors causing constriction of the body's arteries. This constriction raises the total resistance of blood flow, elevating blood pressure to high levels, which is known as HTN. The body's induced hypertension is an attempt to restore blood flow to the damaged, ischemic brain. The sympathetic stimulation also increases the rate of heart contractions and cardiac output. Increased heart rate is also known as Tachycardia. This combined with hypertension is the first stage of the Cushing reflex.

Meanwhile, baroreceptors in the aortic arch detect the increase in blood pressure and trigger a parasympathetic response via the Vagus nerve. This induces bradycardia, or slowed heart rate, and signifies the second stage of the reflex.Bradycardia may also be caused by increased ICP due to direct mechanical distortion of the vagus nerve. Mechanical distortion of the vagus nerve stimulates a parasympathetic response, which can in turn induce bradycardia.
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Old 04-29-2013
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Default My answer

My answer Is B
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Old 04-30-2013
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Default guess

B heart rate, it can be seen especially in children patients,
show bradycardia.
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Old 05-06-2013
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think its b??
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Old 05-06-2013
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Default Explanation.

Quote:
Originally Posted by cybron View Post
Can any1 plz explain..
all the others are in pairs lol. co and contractility are the same. MAP and TPR are the same. i mean affect each other heavily. the only thing left there is hr which hardly affects the others.
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