What are the effects of parathormone in the kidney?
I. it decreases the level of release of calcium
II. it increases the reabsorption of phosphate, which binds to calcium, increasing its blood concentration
III. it stimulates the reabsorption of calcium in the proximal convoluted tubule
IV. it promotes the elimination of phosphates by decreasing their tubular reabsorption
A. II and III
B. I and III
C. II only
D. I and IV
E. None of them
What’s the answer? I think I got it but I’m unsure whether it’s right before I explain it
Okay so first let’s do the elimination method:
1 - Parathormone does control both the reabsorption of calcium as well as the release of calcium so this could be correct
2 - It doesn’t reabsorb phosphate, one of the hormone’s main functions is the excretion of phosphate by blocking reabsorption of phosphate in the proximal tubule. So this is wrong
3 - It does reabsorb calcium however not in the proximal convoluted tubule, it promotes calcium reabsorption in the ascending loop of Henle, distal tubule, and collecting tubule.
4 - This is correct as I stated that it does make sure excretion of phosphate occurs by blocking reabsorption of phosphate in the proximal tubule or their “tubular reabsorption” as stated in the question.
Hope this helps! Remember this hormone acts on the bones, kidneys and the small intestine too
bones - stimulates the release of calcium from large calcium stores in the bones into the bloodstream.
intestines - – parathyroid hormone indirectly increases calcium absorption from food in the intestine, via its effects on vitamin D metabolism.
It is mainly controlled by the negative feedback of calcium levels in the blood to the parathyroid glands.
Thank you. May I know where can I read the details to remember about Parathormone?
Google definitely helps! I used this site Hormones | You and Your Hormones from the Society for Endocrinology to study on all the hormones :)) It gives a very concise but useful description of all the hormone functions. You don’t need to know all of them just the important ones. May I ask where you found this question?
I bought a package on imattestbusters.com.
Thank you for your recommendation.