Question

Which of the following factors prevents the formation of blood clot within blood vessels

Answer 1

Well…. It is a complex process where many chemical factors strike a balance between them in order to make it flow in continuation…

Blood doesn’t clot until and unless there is oxygen presence. Either in case of internal bleeding or external bruises..
Inside the body, liver secretes a substance called heparin an anticoagulant chemical which prevents clotting of blood in blood vessels. But if there is internal injury, platelets break to release a thermoplastic substance and it initiates clotting. Remember internal injury allow oxygen presence there as well as extra surface where heparin is not present…
The process begins whenever flowing blood comes into contact with specific substances in your skin or in blood vessel walls. When they touch, it usually means the skin or blood vessel wall is broken.

Tiny bits in our blood called platelets get "turned on" by triggers released when a blood vessel is damaged. They stick to the walls in the area and each other, changing shape to form a plug that fills in the broken part to stop blood from leaking out.

When activated, platelets also release chemicals to attract more platelets and other cells, and to set off the next step.

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