In case of dehydration, secretion of all harmones increases expect one mark this except one `"_______"`

Options

A. Renin
B. Aldosterone
C. Vassopressin
D. ANF

Answer

**Step-by-Step Solution:**

1. **Understanding Dehydration**: Dehydration refers to a condition where there is a significant loss of water (H2O) from the body. This can occur due to various reasons such as excessive sweating, diarrhea, or insufficient water intake.

2. **Body's Response to Dehydration**: In response to dehydration, the body aims to conserve water. One of the primary ways the body conserves water is by producing concentrated urine.

3. **Hormones Involved in Water Conservation**:
- **Renin**: This hormone is secreted by the kidneys and plays a role in the renin-angiotensin-aldosterone system (RAAS), which helps in sodium reabsorption and consequently water retention.
- **Aldosterone**: This hormone works alongside renin to promote sodium reabsorption in the kidneys, which helps in retaining water and forming concentrated urine.
- **Vasopressin (ADH)**: Also known as antidiuretic hormone, vasopressin increases water reabsorption in the kidneys, leading to concentrated urine formation.

4. **Identifying the Exception**: The question asks which hormone does not increase during dehydration. The fourth hormone mentioned is **Atrial Natriuretic Factor (ANF)**.
- **ANF**: This hormone is secreted by the heart and promotes the excretion of sodium (natriuresis) and water, leading to the production of dilute urine. Therefore, during dehydration, the secretion of ANF decreases as the body tries to conserve water.

5. **Conclusion**: The hormone that does not increase during dehydration is **Atrial Natriuretic Factor (ANF)**.

**Final Answer**: ANF

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