Some Bio related questions

[orangetea]

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So these are just some thought questions I had that I couldn't really find answers to online.. Like concrete answers.

1. So osteoblast and osteoclasts are always working right? Their actions are not necessarily dependent on parathyroid hormone. The only reason PTH acts on osteoclasts is when there's calcium deficiency?

2. How is thyroxin and the kidney related because they are but I couldn't figure out their relationship. Does the Kidney filter it out? idk =/

3. For recyrstalization, to remove impurities when would you wash it with cold water versus heating it?


That's all for now.
Thanks friends 🙂

 

[lumpyduster]

I can only offer an answer to three - but if your impurities are water soluble and your crystal isn't really water soluble, then you can just rinse the impurities away. But let's say your impurity is also not soluble in water and is trapped inside the crystal - then you would do recrystalization.

 

[sillyjoe]

So these are just some thought questions I had that I couldn't really find answers to online.. Like concrete answers.

1. So osteoblast and osteoclasts are always working right? Their actions are not necessarily dependent on parathyroid hormone. The only reason PTH acts on osteoclasts is when there's calcium deficiency?

2. How is thyroxin and the kidney related because they are but I couldn't figure out their relationship. Does the Kidney filter it out? idk =/

3. For recyrstalization, to remove impurities when would you wash it with cold water versus heating it?


That's all for now.
Thanks friends 🙂

1. Bone is in a constant state of resorption (osteoclast) and mineralization (osteoblast). There is always a basal level of both PTH hormone and a basal level of bone resorption / mineralization (remodeling). PTH just regulates the ratio of bone resorption to bone mineralization. In addition, PTH does not actually directly interact with the osteoclast, which interestingly, does not contain a receptor for PTH. PTH actually binds to osteoblasts and through paracrine signaling causes a proliferation of osteoclasts. Just to summarize: bone resorption and mineralization is always going on and PTH modifies this when there is low calcium by indirectly activating osteoclasts. This is way over the top for MCAT and will be learnt in depth in medical school.

2. Thyroxin effects renal development and physiology by multiple mechanisms. Both the kidney and thyroid functioning can effect one another in many ways relating to GFR, renin-angiotensin system, and renal development. The kidney is actually one organ that "activates" thyroid hormone to triiodothyronine. When there are issues with the thyroid hormone it has a great effect on the kidney's ability to maintain water and osmolar homeostasis. Even kidney disease has notable effects on the hypothalamus–pituitary–thyroid axis so it goes both ways. Finally, the kidney is one of the major organs responsible for elimination of thyroid hormone from the body. Again, this is way out of the scope of the MCAT.

3. Can't help you yet with this orgo question. I have to read the TBR chapter on experiments 🙂

 

[sillyjoe]

 

[orangetea]

Thanks so much!!!