https://www.youtube.com/watch?v=CMZ2AormwgU https://bb.ndsu.nodak.edu/bbcswebdav
ID: 71376 • Letter: H
Question
https://www.youtube.com/watch?v=CMZ2AormwgU
https://bb.ndsu.nodak.edu/bbcswebdav/pid-2961857-dt-content-rid-15730710_2/xid-15730710_2
1. Using the information from the video and the graph attached to this assignment about maintenance of a constant GFR over a range of MAP, determine what adjustment would have to be made if a person had a MAP of:
a. 85
b. 130
2. What stimuli would be used to trigger autoregulatory adjustments in each of the above situations.
3. If a person had a blood pressure reading of 80/45, would autoregulation be able to maintain his GFR at 180 L/day? Explain how you arrived at your answer. You will need to calculate this person's MAP in order to answer this question.
Explanation / Answer
1)At 85 mmHg of MAP
When there is a drop in systemic blood pressure, it causes the dilation of afferent arterioles and thus increases the glomerular hydrostatic pressure, which helps in the maintenance of normal GFR .
At 135 mmHg of MAP
Whenever the mean arterial pressure increases, the renal autoregulation comes into action and it causes the afferent arteriole to constrict and thus prevents the pressure from increasing and thus it will not be transmitted to the glomerular capillaries and so steady GFR will be maintained.
2) Myogenic mechanism triggers antiregulatory adjustments in each of the above situations.
3) Mean Arterial Pressure (MAP) = Diastolic pressure + (1/3xPulse Pressure)
First calculate Pulse pressure= Systolic Pressure – Diastolic pressure
=80-45
=35
MAP=45 + (1/3x35)=45+11.7=56.7=57
So, here the MAP is 57.
Intrinsic controls or autoregulation will play a role in the maintenance of steady GFR when the MAP ranges from 80 to 180 mm Hg. But if it drops below 80 or goes beyond 180 mm Hg, autoregulation cannot maintain constant GFR at 180 L/day..
In this case, extrinsic control will take over the job, which mainly involves neural and hormonal mechanisms. It is maintained by sympathetic nervous system and Renin angiotensin mechanism.
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