Major pathway of excretion of Calcium is:
- A- Kidney.
- B- Gut.
- C- Kidney and Gut.
- D- None of the above.
The major pathway of excretion for calcium is actually C. Kidney and Gut, although the kidney plays a more significant role.
Here's why:
Kidney:
- Around 60-70% of the filtered calcium in the kidneys (from dietary intake and bone resorption) gets reabsorbed back into the bloodstream.
- Only about 5-10% of the filtered calcium is actually excreted in the urine.
- However, the kidney plays a crucial role in regulating calcium excretion by adjusting the reabsorption rate based on various factors like dietary intake, vitamin D levels, and parathyroid hormone (PTH) levels.
Gut:
- Approximately 80-90% of the ingested calcium is not absorbed in the gut and is excreted in the feces.
- This unabsorbed calcium mostly comprises insoluble salts that pass through the digestive system without being broken down and absorbed.
- However, the gut also plays a role in regulating calcium absorption and excretion by influencing the solubility of calcium and its interaction with other dietary components.
Therefore, while the gut ultimately excretes more calcium in terms of quantity, the kidney is more crucial in regulating the total body calcium balance through its control over reabsorption and excretion.
So, C. Kidney and Gut is the most accurate answer for the major pathway of calcium excretion.
