In humans one of the constituents of the pancreatic juice which is poured into the duodenum is

Options

A. trypsinogen
B. chymotrypsin
C. trypsin
D. enterokinase.

Explanation

To answer the question about one of the constituents of pancreatic juice that is poured into the duodenum in humans, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Pancreatic Juice**:
- Pancreatic juice is a digestive fluid produced by the pancreas. It contains several enzymes that aid in digestion, particularly of proteins, carbohydrates, and fats.

2. **Identifying the Enzymes in Pancreatic Juice**:
- The pancreatic juice contains several proenzymes (inactive enzymes) that are secreted by the pancreas. These include:
- Trypsinogen
- Chymotrypsinogen
- Procarboxypeptidase
- Elastase

3. **Function of Proenzymes**:
- These proenzymes are inactive forms of enzymes. They need to be activated to perform their function of digesting proteins.

4. **Activation of Trypsinogen**:
- Among the proenzymes, trypsinogen is one that is secreted into the duodenum. It is activated to its active form, trypsin, by the enzyme enterokinase, which is secreted by the intestinal mucosa.

5. **Conclusion**:
- Therefore, the correct answer to the question is that one of the constituents of pancreatic juice that is poured into the duodenum is **trypsinogen**.

### Final Answer:
- **Trypsinogen** is the constituent of pancreatic juice that is poured into the duodenum.