Which of the following hormone acts upon the renal tubule and blood capillaries?

Options

A. Glucagon
B. Aldosterone
C. Vasopressin
D. Glucocorticoids

Explanation

To solve the question "Which of the following hormone acts upon the renal tubule and blood capillaries?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Options**: The options given are glucagon, aldosterone, vasopressin, and glucocorticoid.

2. **Evaluate Glucagon**:
- Glucagon is a hormone secreted by the alpha cells of the pancreas.
- Its primary role is in glucose metabolism, specifically increasing blood glucose levels by promoting glycogenolysis.
- **Conclusion**: Glucagon does not act on the renal tubule or blood capillaries. **(Incorrect option)**

3. **Evaluate Aldosterone**:
- Aldosterone is a hormone secreted by the adrenal cortex.
- It is a mineralocorticoid that plays a significant role in maintaining electrolyte balance and water retention.
- While it affects kidney function, its primary action is on the renal tubules to regulate sodium and potassium levels, not directly on blood capillaries.
- **Conclusion**: Aldosterone is not primarily acting on blood capillaries. **(Incorrect option)**

4. **Evaluate Vasopressin**:
- Vasopressin, also known as antidiuretic hormone (ADH), is synthesized in the hypothalamus and released by the posterior pituitary gland.
- Its main function is to promote the reabsorption of water in the kidneys, particularly in the distal convoluted tubules and collecting ducts.
- Vasopressin also affects blood capillaries by causing vasoconstriction, which can influence blood pressure.
- **Conclusion**: Vasopressin acts on both the renal tubule and blood capillaries. **(Correct option)**

5. **Evaluate Glucocorticoids**:
- Glucocorticoids, such as cortisol, are secreted by the adrenal cortex and are involved in carbohydrate metabolism and stress response.
- They do not have a direct action on renal tubules or blood capillaries.
- **Conclusion**: Glucocorticoids do not act on the renal tubule or blood capillaries. **(Incorrect option)**

### Final Answer:
The hormone that acts upon the renal tubule and blood capillaries is **vasopressin**.

---