PTH and Calcitonin

[miringains]

I always mess up my line of thinking.... ugh I am frustrated

For example: Prior to eating a meal, a person has very low blood calcium... what are the 2 levels of the hormones in this persons body?? After digesting a calcium rich meal, the blood calcium levels rise very high.


Alright so my line of thinking

--> You have low blood calcium.... it means that calcitonin is overactive, and PTH is not active enough

EDIT2 : Is this line of thinking wrong because you would have to have some kind of disease for this to be true?


--> Your blood calcium is low, so to get back to homeostasis, your body will release PTH to bring up blood calcium levels.


I believe that the first line of thinking I have here is INCORRECT. However I cannot put my hand on why... before the person eats the meal, how would the 2 hormone levels be?


EDIT: Am I supposed to think of how the hormones will be at that very moment of time, or what was happening before, or what will happen after?

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[shaboobly]

both hormones are dependent on the blood calcium levels. too much calcium in the blood and calcitonin is secreted to TONE down the amount, if too little calcium is in the blood PTH will be secreted to increase the blood calcium level.

the amount of calcium in the blood depends on a number of things, but probably the most important is the relationship it has with bone remodeling. PTH will induce more activity in the osteroclasts because these cells break down bone and release calcium in the blood. osteoblasts take up calcium from the blood and build new bone.

it's too hard to say what the hormone levels will be before someone eats because you arent given enough information.

 

[curt656]

Calcitonin only results in modest changes and is not a critical factor in calcium levels in blood. It's more of a fine-tuning mechanism more than anything versus PTH which has a much more pronounced effect on blood calcium.

I surmise that calcitonin levels are decreasing before a meal at which time PTH levels are ramping up to increase osteoclast activity in order to increase calcium levels. This response will be mitigated somewhat once calcium levels increase as a result of eating a meal. This will stimulate an increase in calcitonin in order to reduce osteoclast activity.

I am not 100% certain, but think I am correct.