Gastrin and secretin are secreted respectively by :

Options

A. Stomach and small intestine
B. Stomach and stomach
C. Small intestine and small intestine
D. Small intestine and stomach

Answer

To solve the question regarding the secretion of gastrin and secretin, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Hormones**: The question asks about two specific hormones: gastrin and secretin.

2. **Understand the Source of Gastrin**: Gastrin is a hormone that is primarily secreted by the G cells located in the gastric mucosa of the stomach. Its main function is to stimulate the secretion of gastric acid (HCl) and promote gastric motility.

3. **Understand the Source of Secretin**: Secretin is a hormone that is secreted by the S cells in the duodenum, which is the first part of the small intestine. Secretin plays a crucial role in regulating the pH of the small intestine by stimulating the pancreas to release bicarbonate, which neutralizes stomach acid.

4. **Match the Hormones to Their Sources**: Based on the information gathered:
- Gastrin is secreted by the stomach.
- Secretin is secreted by the small intestine.

5. **Evaluate the Options**: The options provided are:
- A) Stomach and small intestine
- B) Stomach and stomach
- C) Small intestine and small intestine
- D) Small intestine and stomach

From our understanding:
- Option A (Stomach and small intestine) is correct.
- Options B, C, and D are incorrect based on the sources of the hormones.

6. **Conclusion**: The correct answer to the question is that gastrin is secreted by the stomach and secretin is secreted by the small intestine.

### Final Answer:
**Gastrin and secretin are secreted respectively by the stomach and small intestine.**

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