Hormone having stimulatory effect on heart is

Options

A. Thyroxine
B. Gastrin
C. Glucagon
D. Adrenaline.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a hormone that has a stimulatory effect on the heart. This means we need to identify which of the listed hormones increases heart activity.

2. **Analyzing the Options**:
- **Thyroxin**: This hormone is produced by the thyroid gland and primarily regulates metabolism. While it does have effects on the cardiovascular system, its main role is not directly stimulating the heart. Thus, it is not the correct answer.

- **Gastrin**: This hormone is secreted by the stomach and is responsible for stimulating gastric acid secretion to aid digestion. It does not influence heart activity, making this option incorrect.

- **Glucagon**: Released by the alpha cells of the pancreas, glucagon's primary function is to increase blood glucose levels. It does not have a direct stimulatory effect on the heart, so this option is also incorrect.

- **Adrenaline (Epinephrine)**: This hormone is produced by the adrenal medulla and is well-known for its role in the "fight-or-flight" response. It increases heart rate, enhances breathing rate, and prepares the body for quick action. This makes adrenaline the correct answer as it has a direct stimulatory effect on the heart.

3. **Conclusion**: After analyzing all the options, the hormone that has a stimulatory effect on the heart is **Adrenaline**.

**Final Answer**: Adrenaline

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