Question

1. In pregnant females, if dietary calcium intake is very low, how is calcium homeostasis maintained?

1. Phosphorus concentration increases to compensate for lack of calcium
2. Calcium is mobilized from the mother’s skeleton
3. Increased vitamin D3 production
4. Increased vitamin E production

2. What is a potential consequence of embryonic exposure to endocrine-disrupting compounds that can bind to estrogen receptors?

1. Increased growth rate and early birth
2. Decrease in size of developing testes
3. Increased rate of ovulation
4. Decreased sperm count
5. B and D

3. Which of the following compounds are, or can be the source of endocrine-disrupting chemicals?

1. Pesticides
2. Plastic
3. High energy drinks
4. A and B
5. A, B, and C

Answer 1

QUESTION 1

The correct answer is Increased vitamin D3 production. To answer this question, we need to review some basic aspects about the synthesis and function of Vitamin D3. One of the first mechanism of calcium homeostasis in pregnant females is the absorption of calcium. To accomplish the absorption, there is an increased production of a specific protein (calcium-binding protein) whose synthesis is stimulated by the active form of vitamin D (1.25-dihydroxyvitamin D).This active form is primarily formed in the kidney by enzymatic hydroxylation of calcifediol. Calcifediol is a prohormone which is produced in the liver by hydroxylation of the vitamin D3. So, to maintain the absorption of calcium, It’s necessary to increase vitamin D3 for the production of the active form of vitamin D.