MCAT Question A Day - 7/4/14 - Answer!
Parathyroid hormone is an important hormone in the control of blood calcium ion levels. Parathyroid hormone directly impacts:
I. bone density
II. renal calcium reabsorption
III. blood calcium concentration
A. I only
B. I and II only
C. I and III only
D. I, II and III
D is correct. Parathyroid honnone stimulates osteoclast (bone resorbtion) activity. It also works in the kidney to slow calcium lost in urine. It controls blood calcium levels via these two mechanisms.
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