Watch the following video to understand how autoregulation can maintain a consta

Question

Watch the following video to understand how autoregulation can maintain a constant GFR as mean arterial pressure (MAP) changes. https://www.youtube.com/watch?v=CMZ2AormwgU

1. Using the information from the video 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

1a. 70-100 mm Hg is the MAP range of a normal person.

So, if MAP is 85 mm Hg, means it is normal. In such a condition, blood will enter the afferent arteriole and leave the nephron via two paths: one is the efferent arteriole through which blood leaves and second is the filtrate through which water and salts leave.

If MAP is increased, this means that the blood will move with more pressure into the efferent arteriole. This situation occurs when efferent arteriole is vasoconstricted. Blood will be able to enter the afferent arteriole, but is unable to leave the efferent arteriole. This causes a build up of pressure in the glomerulus, which pushes the liquid out of the glomerular podocytes. So, the amount of GFR is increased. There is still increased resistance to blood flow, due to vaso constriction of efferent arteriole. Reduced renal blood flow will be there, thus, MAP will increase.

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