Blood Clots
Blood Clots
Clotting (haemostasis) is the mechanism by which broken blood vessels are repaired when damaged
There are two key components of a blood clot – platelets and insoluble fibrin strands
Clotting (haemostasis) is the mechanism by which broken blood vessels are repaired when damaged
- Clotting functions to prevent blood loss from the body and limit pathogenic access to the bloodstream when the skin is broken
There are two key components of a blood clot – platelets and insoluble fibrin strands
- Platelets undergo a structural change when activated to form a sticky plug at the damaged region (primary haemostasis)
- Fibrin strands form an insoluble mesh of fibres that trap blood cells at the site of damage (secondary haemostasis)
Components of a Blood Clot (Scanning Electron Microscopy)
6.3 CLOTTING |
Understanding:
6.3.U3: Clotting factors are released from platelets.
Objective:
6.3.U3: Clotting factors are released from platelets.
Objective:
- Outline two roles of platelets in the blood clotting cascade.
Coagulation Cascade
Coagulation Cascade
The process by which blood clots are formed involves a complex set of reactions collectively called the coagulation cascade
The coagulation cascade involves many intermediary steps, however the principal events are as follows:
The process by which blood clots are formed involves a complex set of reactions collectively called the coagulation cascade
- This cascade is stimulated by clotting factors released from damaged cells (extrinsic pathway) and platelets (intrinsic pathway)
The coagulation cascade involves many intermediary steps, however the principal events are as follows:
- Clotting factors cause platelets to become sticky and adhere to the damaged region to form a solid plug
- These factors also initiate localised vasoconstriction to reduce blood flow through the damaged region
- Additionally, clotting factors trigger the conversion of the inactive zymogen prothrombin into the activated enzyme thrombin
- Thrombin in turn catalyses the conversion of the soluble plasma protein fibrinogen into an insolube fibrous form called fibrin
- The fibrin strands form a mesh of fibres around the platelet plug and traps blood cells to form a temporary clot
- When the damaged region is completely repaired, an enzyme (plasmin) is activated to dissolve the clot