The blood does not clot inside the body because of

Options

A. Oxygenation of blood
B. Absence of fibrinogen in blood
C. Movement of blood
D. Heparin in blood .

Answer

### Step-by-Step Solution:

1. **Understanding Blood Clotting**: Blood clotting is a process where blood transforms from a liquid to a gel, forming a thickened mass known as a clot. This process is essential for stopping bleeding when there is an injury.

2. **Role of Blood Platelets**: Blood platelets, also known as thrombocytes, are crucial in the clotting process. They are small cell fragments derived from larger cells in the bone marrow called megakaryocytes. When a blood vessel is injured, platelets aggregate at the site and form a clot to prevent further bleeding.

3. **Normal Conditions in the Body**: Under normal, healthy conditions, blood does not clot inside the blood vessels. This is important to maintain proper blood flow and prevent unnecessary clot formation that could lead to blockages.

4. **Presence of Anticoagulants**: The reason blood does not clot inside the body is due to the presence of anticoagulants. Anticoagulants are substances that prevent blood from clotting.

5. **Heparin as an Anticoagulant**: One of the key anticoagulants in the blood is heparin. Heparin is secreted by certain white blood cells, specifically basophils and mast cells. It is released into the bloodstream and helps to inhibit the clotting process.

6. **Conclusion**: Therefore, the blood does not clot inside the body primarily because of the presence of anticoagulants like heparin, which prevent the formation of clots under normal physiological conditions.

### Final Answer:
The blood does not clot inside the body because of the presence of anticoagulants, specifically heparin, which is secreted by basophils and mast cells.