Question

Proper blood calcium levels are required for muscle contraction, nerve function, and other critical activities in the body. How does the body maintain homeostasis in response to decreased blood calcium levels? Discuss the main gland, hormone, and target of the hormone.

a) Parathyroid gland, Parathyroid hormone (PTH), Bones and Kidneys
b) Thyroid gland, Thyroxine, Muscles and Brain
c) Pituitary gland, Growth hormone, Liver and Skin
d) Adrenal gland, Cortisol, Lungs and Heart

Answer 1

The parathyroid glands secrete PTH in response to decreased blood calcium levels, targeting bones and kidneys to increase blood calcium levels and maintain homeostasis. The correct option is a).

Step-by-step explanation:

The body maintains homeostasis in response to decreased blood calcium levels primarily through the actions of the parathyroid glands. When there is a drop in blood calcium levels, the parathyroid glands secrete the parathyroid hormone (PTH). PTH has several targets, including the bones, kidneys, and intestines.

In the bones, PTH stimulates the activity of osteoclasts, which are cells that break down bone tissue, resulting in the release of calcium into the blood. In the kidneys, PTH enhances the reabsorption of calcium, preventing its loss through urine.

Furthermore, PTH stimulates the kidneys to produce calcitriol (active form of vitamin D), which promotes calcium absorption from the small intestines into the bloodstream, thereby stabilizing blood calcium levels.

Therefore, the correct answer to maintaining calcium homeostasis in response to decreased blood calcium levels is a) Parathyroid gland, Parathyroid hormone (PTH), Bones and Kidneys. Option a) is the correct one.