hey! it’s me again. 😀 Form5 Biology Chapter 1 . Check this out!
NECESSITY FOR BLOOD CLOTTING
- Prevent excessive blood loss from the body when there is a damage of the blood vessel.
- Maintain the blood pressure.
- Prevent the entry of microorganism and foreign particles into the body.
- Promote wound healing
BLOOD CLOTTING MECHANISM
- When you get cut, platelets exposed to air and become sticky then clump together to plug the wound.
- Clotting factors are released by platelets and damage tissue called thrombokinase.
- Thrombokinase in the presence of calcium ions, converts prothrombin into thrombin
- The formation of prothrombin in the livers requires vitamin K
- Thrombin converts soluble plasma protein, fibrinogen into insoluble fibrin fibres which form a meshwork of thread over the wound.
- As the blood flows, erythrocytes and platelets are trapped in the fibrin fibres and a blood clot are form.
CONSEQUENCES OF AN IMPAIRED BLOOD CLOTTING MECHANISM
PROBLEMS RELATED TO BLOOD CLOTTING INCLUDE HAEMOPHILIA AND THROMBOSIS
- Haemophilia is a heritance disease due to the lack of certain gene for the production of certain factors.
- This is an impaired clotting mechanism which causes serious bleeding particularly in the joints
- The afflicted person may die as the result of excessive bleeding from even minor cuts and bruises because blood clotting cannot take place.
- Sometimes a local blood clot(thrombus) is formed on the damaged rough inner wall of the artery.
- This may cause blockage of the artery known as thrombosis.
- Embolus formed when the thrombus dislodges and is carried away by blood circulation.
- It may trapped in a small artery where it blocked the blood flow, this condition called embolism.
- The blocked coronary artery cuts off the supply of oxygen and nutrients to the heart muscles, hence causes the heart attack.
here are the link about the blood clotting : http://www.youtube.com/watch?v=–bZUeb83uU&feature=related