Blood 2 Flashcards
Platelets (thrombocytes) breakdown
Nucleus free fragments
-2-3um in diameter in inactive state
=not true cells, pieces of giant megabyte cell
Platelets (thrombocytes) contain 2 special types of granules:
- Dense core granules
- alpha-granules
-both are important in hemostasis in keeping blood within a damaged vessel
-contain clotting factor etc
Hemostasis
The prevention of hemorrhage (bleeding) from a damaged vessel
-achieved through 3 step process
3 Steps to get Hemostasis (stopping hemorrhage)
- vasoconstriction
- Platelet Plug Formation
- Coagulation (coagulation cascade)
How does Vasoconstriction prevent Hemorrhage
Closing the vessel, preventing blood flow to damaged region
-triggered by direct injury to vascular muscle, release of paracrines signals, or platelets
-bring pressure down in vessel so mechanical seal can be applied in form of a clot
-signaled by serotonin and thromboxane A2 from platelet
How does Platelet Plug Formation help Hemostasis
-during vasoconstriction, contain cell surface receptors
-breach of endothelium exposes collagen etc which cause platelets to bind
-binding of integrity causes intracellular signalling release serotonin for vasoconstriction, and more to release more platelets
How does Coagulation cascade help Hemostasis
-fibrin protein mesh stabilizes platelet plug by reinforcing it
-begins to pathways of activation (intrinsic, extrinsic) that converge onto common
Intrinsic Pathway Start and Final Product
Starts with factor 12 converted when comes into contact with damaged wall
Final product is Factor Active 10
Proteolysis
Breakdown of proteins into smaller polypeptides or amino acids
extrinsic Pathway Start and Final Product
Outside vascular system
-starts with Factor 7 leaving vessel through damage region
Final product is Activated 10
-produced from intrinsic and extrinsic -important for common pathway
Common pathway Start and Final product
Starts with Activated 10 from intrinsic and extrinsic
-used to create thrombin, converts fibrinogen to
Final product being a Stable Fibrin Cloth
Hemophilia
Several diseases in which one of the factors in the coagulation cascade is defective or lacking
-easily bruise, random bleeding
-bleeding in joints and muscles
Hemophilia A
Has a factor 13 deficiency
-activates 10
=most common in about 80% cases
X linked recessive gene
Hemophilia B
Factor 9 Deficiency
X linked recessive gene
Anticoagulant factors
Too much coagulation
=very bad
Stroke, heart attack, etc
