explain in details why blood does not clot in the vessel or body but outside the body it clot
Blood clotting is a complex process of hemostasis that occurs when there is damage to a blood vessel. In the body, blood is constantly flowing through the circulatory system, and specialized cells and proteins work together to prevent excessive bleeding and promote healing of damaged tissues.
Inside blood vessels, the endothelial cells that line the walls of the vessels are smooth and prevent the formation of clots. Additionally, the constant flow of blood helps to prevent the accumulation of platelets and clotting factors that could lead to the formation of a clot.
However, when there is damage to a blood vessel, the endothelial cells are disrupted, exposing the underlying tissue to platelets and clotting factors. This triggers a series of events that leads to the formation of a blood clot, which helps to stop bleeding and promote tissue repair.
In contrast, when blood is outside the body, the natural flow of blood is disrupted, and the lack of endothelial cells allows for the accumulation of platelets and clotting factors. This can lead to the formation of a clot outside the body, such as when blood is spilled and allowed to sit undisturbed.
Overall, the complex interplay of cells and proteins in the body helps to prevent the formation of clots within the blood vessels while promoting clot formation in response to injury or damage. Outside the body, where these regulatory mechanisms are absent, blood can clot more easily.