20. Platelets,Hemostasis and disorder of coagulation Flashcards
What is Hemostasis ?
-Refers to a process that prevents blood loss from a broken blood vessel ; essential to life
What three major steps that Hemostasis has?
Vascular spasm(constriction of vessel)
-Reduces blood flow through a damaged vessel
Formation of a platelet plug
-Unstable
Blood coagulation(clotting)
-Transformation of blood from liquid into a solid gel
What is the function of platelets and when is it released?
To seal breaks in blood vessel and released when needed by sympathetically induced splenic contraction
How does the production of platelets work ?
Its a self regulating process
What are the regulation factors of Platelets?
-Thrombopoietin
-Hormone produced by liver increases platelet production
-Interleukin-3(IL-3),IL-6,IL-11
What is the platelet plug and what is it stabilized by?
It is a bunch of platelets that clump up and together to form a plug around the site of an injury.
-Stabilized by fibrin network
what is clot formation?
-It reinforces platelet plug and converts blood in the vicinity of vessel injury into a non flowing gel
Clotting factors are always present in _____________ in inactive precursor form
Blood plasma
How is Fibrinogen converted into Fibrin?
By the means of Intrinsic and extrinsic pathway
What is Fibrinogen?
Precursor of fibrin, an insoluble protein=protein meshwork of clot
What is Thrombin?
-Converts fibrinogen to fibrin at site of injury
What is Factor XIII?
-Fibrin stabilizing factor ; xlink fibrin molecules
What is factor x?
-Last component of clotting cascade that activates thrombin from prothrombin
What is a Clotting Cascade?
It is a series of steps involving 12 plasma clotting factors that lead to final conversion of fibrinogen into a stabilized fibrin mesh
What is Intrinsic pathway?
-Involves seven separate steps–> takes long to develop
-Set off when blood clot factors come into contact with exposed collagen in injured vessel or foreign surface such as glass test tube
What is Extrinsic pathway?
-requires only four steps–>it is a fast reaction
-requires contact with tissue factors external to the blood
-Tissue damage and blood vessel break
DRAW the CLOT PATHWAY on slide 37
What is Clot Dissolution?
-Tissue heals
-New cells secrete tissue plasminogen activator
What are examples of Clot busting drugs?
-Anticoagulant drugs
-Fibrinolytic drugs
-Antiplatelet drugs
In abnormal Blood clotting, What is Thrombus?
Abnormal intravascular clot attached to a vessel wall
In abnormal blood clotting, what is an emboli?
-Freely floating clots
What are factors that can cause thromboembolism ?
-Roughend vessel surfaces associated with atherosclerosis
-Imbalances in the clotting-anticlotting systems
-slow moving blood
In abnormal blood clotting, what is septicemic shock ?
-Widespread clotting that is caused by toxins released by infectious bacteria
In abnormal blood clotting, what is Hemophilia?
-Excessive bleeding caused by deficiency of one of the factors in the clotting cascade
-Treatment by infusion of the missing factors into blood
