Define thrombosis.

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Thrombosis**: Thrombosis is defined as the formation of a blood clot within a blood vessel.

2. **Blood Flow Dynamics**: In a healthy blood vessel, blood flows continuously, creating a gradient that circulates throughout the body.

3. **Initiation of Clotting**: If there is damage to the blood vessel, it can trigger the formation of platelets. These platelets are crucial for the clotting process.

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