Hormone, responsible for raised level of `Ca^(+2)` in blood is

Answer

To determine the hormone responsible for raising the level of calcium ions (Ca²⁺) in the blood, follow these steps:

### Step-by-Step Solution:

1. **Identify the Hormone**: The hormone responsible for increasing the levels of calcium in the blood is known as the **parathyroid hormone (PTH)**.

2. **Source of the Hormone**: Parathyroid hormone is secreted by the **parathyroid glands**, which are small glands located behind the thyroid gland in the neck.

3. **Mechanism of Action**: Parathyroid hormone increases blood calcium levels through several mechanisms:
- **Increased Intestinal Absorption**: It enhances the absorption of calcium from the food we eat in the intestines.
- **Mobilization from Bones**: PTH stimulates the release of calcium from bones into the bloodstream, thus increasing blood calcium levels.

4. **Contrast with Other Hormones**: It is important to note that there is another hormone called **calcitonin** (also known as thyrocalcitonin) which has the opposite effect. Calcitonin is secreted when calcium levels in the blood are high, and it works to lower those levels by inhibiting bone resorption and increasing calcium excretion in the kidneys.

5. **Conclusion**: Therefore, the hormone responsible for raising the level of calcium ions in the blood is the **parathyroid hormone (PTH)**.