Low blood levels of calcium stimulate the release of which hormone?

• A. Calcitonin
• B. Insulin
• C. Parathyroid hormone (PTH)
• D. Aldosterone

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the role of calcium in the body. Calcium is essential for various physiological processes, including muscle contraction, nerve signaling, and blood clotting. The body tightly regulates calcium levels to maintain homeostasis.
2. Step 2: Learn about the hormones involved in calcium regulation. Parathyroid hormone (PTH) and calcitonin are the primary hormones responsible for maintaining calcium balance. PTH increases blood calcium levels, while calcitonin decreases them.
3. Step 3: Recognize the stimulus for PTH release. Low blood calcium levels stimulate the parathyroid glands to release PTH. This hormone acts to increase calcium levels by promoting calcium release from bones, increasing calcium absorption in the intestines, and reducing calcium excretion by the kidneys.
4. Step 4: Differentiate between the listed hormones. Calcitonin lowers blood calcium levels, insulin regulates blood glucose, and aldosterone controls sodium and potassium balance. None of these, except PTH, are directly involved in increasing blood calcium levels.
5. Step 5: Conclude that the correct answer is Parathyroid hormone (PTH), as it is specifically released in response to low blood calcium levels to restore balance.