Which hormone increases blood calcium levels by stimulating osteoclast activity in the skeletal system?

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

Answer: (A)

Verified step by step guidance

1. Identify the role of each hormone listed in the options. For example, Parathyroid Hormone (PTH) is known to regulate calcium levels in the blood, while insulin regulates blood sugar, growth hormone promotes growth, and calcitonin lowers blood calcium levels.
2. Understand the function of osteoclasts in the skeletal system. Osteoclasts are specialized cells that break down bone tissue, releasing calcium into the bloodstream.
3. Determine which hormone stimulates osteoclast activity. Parathyroid Hormone (PTH) is responsible for increasing osteoclast activity, leading to the release of calcium from bones into the blood.
4. Eliminate the incorrect options based on their functions. Insulin and growth hormone do not directly affect calcium levels, and calcitonin has the opposite effect by reducing blood calcium levels.
5. Conclude that the hormone which increases blood calcium levels by stimulating osteoclast activity is Parathyroid Hormone (PTH).