Name the main control of the kidney that acts in each situation, and say what it does…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Name the main control of the kidney that acts in each situation, and say what it does.
- A man in a hot field loses much water in sweat.
- A person loses a large volume of blood in an accident, and the blood pressure falls.
- A patient is given a large volume of fluid into a vein, and more blood flows into the atria.
- Which of these three acts as a check on the renin-angiotensin mechanism?
Need a reminder? The key ideaShow
ADH is made in the hypothalamus and released by the neurohypophysis. It helps the reabsorption of water and prevents diuresis. Renin from the JG cells changes angiotensinogen to angiotensin I and II. Angiotensin II narrows the vessels and makes the adrenal cortex release aldosterone. ANF from the atria widens the vessels and lowers the blood pressure. In a model, the urine volume is .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) ADH. The osmoreceptors are activated and the neurohypophysis releases ADH. It helps the reabsorption of water and the urine becomes small and concentrated.
Step 2. (b) The renin-angiotensin mechanism. The JG cells release renin, and angiotensin II narrows the vessels and aldosterone gives Na and water reabsorption, so the blood pressure rises.
Step 3. (c) ANF. It is released from the atria, causes vasodilation and lowers the blood pressure. The extra fluid is lost.
Step 4. (d) ANF is the check.
Answer: (a) ADH; (b) renin-angiotensin; (c) ANF; (d) ANF.
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