The calcium level is increased in blood by promoting

Options

A. Dissolution of skeletal structures
B. Excretion of calcium in urine
C. Mineralisation of bones
D. Mineralisation of teeth

Answer

To answer the question regarding how calcium levels are increased in the blood, we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding Calcium Regulation**: The body regulates calcium levels in the blood through hormones, primarily Parathyroid Hormone (PTH) and Calcitonin. These hormones have opposing effects on calcium metabolism.

2. **Role of Parathyroid Hormone (PTH)**: PTH is secreted by the parathyroid glands, which are located behind the thyroid gland. When calcium levels in the blood are low, PTH is released into the bloodstream.

3. **Effects of PTH**: PTH increases the concentration of calcium ions in the blood through several mechanisms:
- It stimulates the release of calcium from bones into the bloodstream (demineralization).
- It enhances the reabsorption of calcium in the kidneys, reducing the amount excreted in urine.
- It promotes the activation of vitamin D, which increases intestinal absorption of calcium from food.

4. **Role of Calcitonin**: Calcitonin, also known as Thyrocalcitonin, is produced by the parafollicular cells (C cells) of the thyroid gland. Its primary role is to lower blood calcium levels when they are elevated.

5. **Antagonistic Effects**: PTH and Calcitonin have antagonistic effects on calcium metabolism. While PTH increases calcium levels in the blood, Calcitonin works to decrease them by promoting the deposition of calcium in the bones.

6. **Conclusion**: Therefore, the increase of calcium levels in the blood is primarily promoted by Parathyroid Hormone (PTH), which facilitates the release of calcium from bones and enhances its absorption in the kidneys and intestines.

### Final Answer:
The calcium level is increased in blood by promoting the action of Parathyroid Hormone (PTH).

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