1.3 THE MECHANISM OF 1.3 THE MECHANISM OF BLOOD CLOTTINGBLOOD CLOTTING

1. Blood clotting is necessary to1. Blood clotting is necessary to a) prevent serious blood lossa) prevent serious blood loss b) prevent the entry of b) prevent the entry of microorganisms microorganisms and foreign and foreign particlesparticles c) maintain blood pressurec) maintain blood pressure d) maintain circulatory of blood in a d) maintain circulatory of blood in a closed circulatory systemclosed circulatory system

HUMAN CIRCULATORY SYSTEMHUMAN CIRCULATORY SYSTEM

BLOOD CLOTTING - BLOOD CLOTTING - CoagulationCoagulation

a) When a) When a damagea damage to the vessel is to the vessel is smallsmall

Clumping together of platelets Clumping together of platelets (platelet aggregation forming (platelet aggregation forming platelet platelet plugsplugs))

Blood clotting (triggered by platelet Blood clotting (triggered by platelet aggregation)aggregation)

platelet plugs stop blood lossplatelet plugs stop blood loss

2. When the damage in the vessel is more 2. When the damage in the vessel is more severesevere

Platelets release enzymes which combines Platelets release enzymes which combines with clumped platelets, damage cells and with clumped platelets, damage cells and clotting factors to form clotting factors to form thromboplastinthromboplastin ((thrombokinasethrombokinase))

Thromboplastin combines with Thromboplastin combines with calcium calcium ionsions and and vitamin Kvitamin K to convert plasma to convert plasma protein protein prothrombinprothrombin (not active) to (not active) to thrombin thrombin ((active)active)

Thrombin converts plasma protein Thrombin converts plasma protein fibrinogen fibrinogen (soluble) to (soluble) to fibrinfibrin (insoluble) (insoluble)

SCHEMATIC DIAGRAMSCHEMATIC DIAGRAM

Vitamin K Prothrombin

Ca++ ion

Platelets

Thromboplastin

Other factors

Thrombin

Fibrinogen Fibrin

Fibrin forms a thick, sticky net of Fibrin forms a thick, sticky net of tangled threads which trap tangled threads which trap erythrocyteserythrocytes

This jelly like blood clot seals the This jelly like blood clot seals the wound to prevent further blood losswound to prevent further blood loss

The external side of the clot which is The external side of the clot which is exposed to air dries out and forms a exposed to air dries out and forms a scab which will drop off once scab which will drop off once complete healing underneath is complete healing underneath is completecomplete

PHOTOMICROGRAPH OF BLOOD PHOTOMICROGRAPH OF BLOOD CLOTCLOT

HAEMOPHILIAHAEMOPHILIA

Inherited blood disorderInherited blood disorderLack of protein needed for Lack of protein needed for

normal blood clottingnormal blood clottingBlood clots slowly/not at allBlood clots slowly/not at allUncontrolled/excessive bleeding Uncontrolled/excessive bleeding

from minor cutsfrom minor cutsMay also experience May also experience

spontaneous internal bleedingspontaneous internal bleeding

THROMBOSISTHROMBOSIS Blood clots may form within the blood vessels Blood clots may form within the blood vessels

due to various factors such as defects in the due to various factors such as defects in the vessel walls or blood that flows too sowly.vessel walls or blood that flows too sowly.

Clot formation inside unbroken blood vessel Clot formation inside unbroken blood vessel is called is called TROMBOSISTROMBOSIS

The clot is calledThe clot is called TROMBUS TROMBUS

Sometime trombus may dislodged and travel Sometime trombus may dislodged and travel in the bloodstream and called in the bloodstream and called EMBOLUS.EMBOLUS.

Arterial thrombosis cuts off OArterial thrombosis cuts off O22 and nutrition and nutrition - Heart (heart attack)- Heart (heart attack) - Brain (stroke)- Brain (stroke)