clotting mechanism Flashcards
1) . when it clots, blood changes state? process?
2) . when bleed occurs which part of vessel has obviously been damaged?
1) . it goes from liquid to gel, forming a blot clot. process is coagulation/clotting
2) . endothelium
why do we need a control system for clotting?
The reactions that result in the formation of a blood clot are balanced by other reactions that stop the clotting process and dissolve clots after the blood vessel has healed. Without this control system, minor blood vessel injuries could trigger widespread clotting throughout the body—which actually happens in some diseases.
when bleeding occurs, what’s the sequence of protocol followed?
first, blood flow from damaged vessel is stopped (HAEMOSTASIS), then repair.
or other more structured form is:
haemostasis as a whole process with following steps:
1). vasoconstriction (so that blood flows out more slowly and clotting can start, even blood pooled outside ,haematoma, presses against the vessel and helps prevent further bleeding)
2). primary haemostasis
3). secondary haemostasis
4). regeneration/repair
haemostasis, too, is of two types: primary haemostasis and secondary haemostasis. In all mammals, clotting involves a cellular component (platelets) and a protein component (clotting factor). we can view the types of haemostasis on the basis of the component at work. Primary haemostasis employs platelets immediately to form a plug and secondary haemostasis involves cascade mechanism of clotting factors.
clotting disorders may lead to
contusions (bruises, haematoma of tissue), thrombosis (formation of blood clot inside vessel), haemorrhage
(haematoma: localised bleeding outside of vessel)
clotting works how?
certain clotting factors respond in a cascade mechanism which ultimately leads to the formation of an insoluble, fibrous mesh like structure made of protein fibrin (from “fibre”, literally thread-like). It’s the body’s equivalent to stitching.
types of cascade mechanisms
two types: intrinsic and extrinsic pathways (Tissue factor pathway) which ultimately lead to a common pathway.
extrinsic pathway begins with tissue factor/thromboplastin being released from damaged blood vessels. It is activated by calcium ions (factor 4).
who plays the central role in blood coagulation pathways? how and why?
THROMBIN is the most important constituent of blood clotting mechanism in terms of its feedback mechanism role. The major, major role of the extrinsic or tissue factor mechanism is to create a thrombin burst, even otherwise, thrombin formation is ultimately important because it converts fibrinogen (factor 1) to insoluble fibrin
which factor is hypothetical? why so?
factor 6: unknown factor, it was earlier assumed to be the activated form of factor 5. Not been isolated/ was but later discovered to be a part of some other factors/not working independently
factor 5: labile factor/proaccelerin
factor 6: accelerin
proconvertin is?
factor 7 or stable factor is also known as proconvertin
which factor deficiency causes haemophilia A?
Factor 8, AHF-A.
In this disorder, the time of clotting increases.
Plasma thromboplastin antecedent is?
factor 11/ AHF-C
factors responsible for three types of haemophilia?
factors 8, 9, 11
1) . surface factor
2) . laki lovand factor
1) . factor 12 or glass/hageman factor
2) . factor 13/ fibrin stabilising factor
why does blood not clot when it has clotting factors swimming around in it?
the factors are in inactivated forms and some (CF) are inactivated by heparin
what could be the different causes of clotting disorders?
1) . liver damage (cirrhosis, liver failure) can reduce the number of clotting factors.
2) . vitamin K deficiency
3) . aplastic anaemia (bone marrow cannot make enough new cells for the body to work normally)
4) . other vitamin deficiencies: folate, cyanocobalamine, iron deficiency
