Which hormone aids in regulating intestinal absorption of calcium and phosphorus?

• A. Insulin
• B. Glucagon
• C. Thyroxine
• D. Calcitriol (active form of vitamin D)

Answer: (D)

Verified step by step guidance

1. Understand the role of calcitriol: Calcitriol is the active form of vitamin D, which plays a crucial role in maintaining calcium and phosphorus homeostasis in the body. It aids in the absorption of these minerals from the intestine.
2. Recognize the importance of calcium and phosphorus: Calcium is essential for bone health, muscle function, and nerve signaling, while phosphorus is vital for energy production and the formation of DNA and RNA.
3. Learn how calcitriol is activated: Vitamin D is converted into calcitriol in the kidneys after being hydroxylated in the liver. This active form then acts on the intestines to enhance the absorption of calcium and phosphorus.
4. Differentiate calcitriol from other hormones: Insulin regulates blood glucose levels, glucagon raises blood glucose levels, and thyroxine regulates metabolism. None of these hormones directly influence calcium and phosphorus absorption like calcitriol does.
5. Connect calcitriol's function to its impact: By increasing calcium and phosphorus absorption, calcitriol ensures that these minerals are available for critical physiological processes, including bone mineralization and cellular function.