BLOOD CLOTTINGMECHANISM

is a body mechanism to reduce and stop blood loss from the injured blood vessel.

BLOOD CLOTTING MECHANISM

The importance of blood clotting

a) Prevent serious blood loss when a person is injured

b) Maintain blood pressure

c) Maintain the circulation of blood in a closed circulatory system

d) Prevent the entry of microorganisms and foreign substances into the body through the damage of blood vessels.

The mechanism of blood clotting

Small injury

Platelets

Severe injury

Fibrin is fibrous protein which aggregates to form a mesh of long threads over the wound, trapping red blood cells and

sealing the wounds.

Fibrin is fibrous protein which aggregates to form a mesh of long threads over the wound, trapping red blood cells and

sealing the wounds.

BLOOD CLOTTING COMPONENT

Fibrin

Red blood cell

Platelet

Exercise

1) Explain how a platelet plug is formed– A platelet plug is formed when platelets stick to

the collagen fibres in the connective tissue and release chemicals that make nearby platelets sticky and clumped together.

2) Thrombin, fibrin, prothrombin and fibrinogen are four types of proteins

Arrange in sequence the involvement of these proteins during blood clotting.

– Prothrombin, thrombin, fibrinogen, fibrin.

Problems related to the blood clotting

• Haemophilia– Is a hereditary disease.– Caused by lack of clotting factors in blood– May cause death due to the excessive

bleeding from minor cuts and bruises.– Also can cause spontaneous internal

bleeding.

• Thrombosis– formation of blood clot in unbroken blood

vessel– Caused by the defect in blood vessel wall or

the blood flows too slowly.

– The clot formed is called thrombus.

– If thrombus travel in blood stream, it is called an embolus.

– embolus stuck in coronary artery- heart attack– Embolus stuck in brain artery- stroke

Problems related to the blood clotting

BLOOD CLOTTING MECHANISMANIMATION

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