What is the functions of dorsal blood vessel in pheretima-

Answer

### Step-by-Step Solution:

1. **Understanding Pheretima**:
- Pheretima is the scientific name for the common earthworm. It is important to recognize that we are discussing the anatomy and physiology of this organism.

2. **Closed Vascular System**:
- Earthworms possess a closed vascular system, which means that the blood circulates within blood vessels and does not flow freely in the body cavity. This system is essential for efficient transport of nutrients and gases.

3. **Dorsal Blood Vessel**:
- The dorsal blood vessel is a key component of the earthworm's circulatory system. It runs along the back (dorsal side) of the earthworm.

4. **Function of the Dorsal Blood Vessel**:
- The primary function of the dorsal blood vessel in Pheretima is to act as a distributing vessel. This means it is responsible for distributing blood throughout the body.
- Specifically, it extends from the first 13 segments of the earthworm and reaches up to the cerebral ganglion, which is the nerve center of the earthworm.

5. **Branches of the Dorsal Blood Vessel**:
- In addition to its main function, the dorsal blood vessel also gives off branches that supply blood to the anterior (front) region of the earthworm. This ensures that the head and other vital organs receive an adequate blood supply.

### Summary of Functions:
- Acts as a distributing vessel for blood.
- Extends to the cerebral ganglion.
- Supplies blood to the anterior region through its branches.

---