Hemostasis Blood Clotting Flashcards
Platelets function
release important clotting chemicals; temporarily patch damaged vessel walls; actively contract tissue after clot formation
Thrombocytopoiesus
production of platelets
What is hemostasis
process that stops bleeding, halts loss of blood through walls of damaged vessels and makes framework for repairs
3 stages of blood hemostasis
stage 1 - vascular phase
stage 2 - platelet phase
stage 3 - coagulation phase
What happens in the vascular phase of hemostasis
- lasts 30 minutes
1. endothelial cells contract to exposed basal lamina to bloodstream
2. endothelial cells release chemical factors (ADP, tissue factor, prostacyclin) and hormones to stimulate smooth muscle contraction and cell division
3. endothelial plasma membrane become “sticky” to cut off blood flow
What happens in the platelet phase of hemostasis
- begins 15 seconds after injury
1. platelets adhere to sticky endothelial surfaces, basal laminae, and exposed collagen fibers
2. platelets stick together to form platelet plugs
What happens in the coagulation phase of hemostasis
formation of a clot
Fibrinolysis definition
slow process of dissolving a clot
Clotting disorders
hemophilia and thrombosis
Describe hemophilia
genetic disorder that causes difficulty in clotting
Describe thrombosis and it’s symptoms
- abnormal blood clot in healthy vessels
- pain, reduced circulation, swelling in affected limb
Describe embolus and it’s symptoms
- travelling blood clot that can potentially get stuck and block blood flow
- chest pain, coughing, sudden shortness of breath
3 coagulation pathways
extrinsic, common, intrinsic
Common coagulation pathway
- intrinsic and extrinsic pathway activate prothrombin activator
- prothrombin splits into thrombin
- thrombin activates fibrinogen into fibrin (forms the clot)
