chapter 19 part 2 Flashcards
platelets
- how many per mm3 of blood
- platelet production
- 3 functions
- 350,000
- thrombocytopoieosis
- release chemicals important for clotting process
- forms temporary patch in wall of damaged blood vessel
- release chemicals important for clotting process
- contracts formed clot
megakaryocyte
- big or small
- sheds what
- # of platelets produced from 1 megakaryocte
- how many days does it circulate in blood for
- very large
- cytoplasm in small membrane - enclosed packets
- 4000
- 9-12 days
platelet abnormalities
-2 types
- thrombocytopenia
2. thrombocytosis
thrombocytopenia
- definition
- what does it cause
- abnormally low platelet count
- causes uncontrolled internal bleeding
thrombocytosis
abnormally high platelet count
hemostasis
- definition
- 3 phases
- stoppage of bleeding in damaged vessel
- vascular phase
- platelet phase
- the coagulation phase
- vascular phase
Vascular phase
- definition
- cutting of vessel wall causes
- component
- immediate response that last ~30 min
- contraction of smooth muscle
- vascular spasm
vascular spasm
- definition
- minimizes what
- decrease diameter of vessel
- minimizes blood loss
Platelet phase
- definition
- 2 components
- begins ~15 sec after injury
- platelet adhesion
- platelet plug
platelet adhesion
platelets begin to attach to exposed vessel surface
platelet plug formation
platelets release various chemicals causing more platelets to adhere
coagulation phase
- definition
- what does it involve
- 3 steps
- begins ~30 sec after injury
- involved Ca++ and 11 different clotting factors
- fibrinogen
- fibrin
- forms threads that seal off damaged vessel (clot)
- fibrinogen
fibrinogen
soluable protein in plasma
fibrin
insoluable protein in plasma
Coagulation: the common pathway
- what does it do
- 4 steps
- forms a clot
- Activated factor X is converted to prothrombinase
- Prothrombinase converts prothrombin to thrombin
- Thrombin converts fibrinogen into fibrin
- fibrin forms the clot
- Activated factor X is converted to prothrombinase
Activated factor X is made where
in the liver
Is prothrombinase an active or inactive enzyme?
active enzyme
prothrombin
- what is it?
- active or inactive enzyme
- protein in plasma
- inactive enzyme
thrombin
-active or inactive enzyme
active enzyme
2 pathways to activated Factor X
- extrinsic
- intrinsic
extrinsic pathway
- what is it triggered by
- 1st or 2nd pathway to initiate clotting
- 7 steps
- factors that lie outside the blood
- 1st pathway
- Tissue damage
- Tissue Factor III
- plasma components (Ca2+ and clotting factor VII)
- Factor VII - tissue factor complex
- activated factor X
- common pathway
- clot
- Tissue damage
intrinsic pathway
- what is it triggered by
- 6 steps
- triggered by platelets found in blood
- exposed collagen fibers at injury site
- activated proenzymes (factor XII)
- Plasma components (platelet factor, Ca2+, clotting factors VIII,XI)
- activated factor X
- common pathway
- clot
- exposed collagen fibers at injury site
control of coagulation
-4 requirements
- calcium
- vitamin K
- clot retraction (syneresis)
- fibrinolysis
calcium requirement
any Ca2+ imbalance will have same affect on clotting
Vitamin K requirement
- why is it used
- obtained by what
- made by what
- to make clotting factors
- by diet
- bacteria in large intestine
clot retraction (syneresis)
- definition
- occurs over a period of how long
- pulls torn edges of vessel closer together to reduce size of damaged area
- over a period of 30 to 60 min
Fibrinolysis
- definition
- 3 steps
- dissolving the clot
- plasminogen (plasma protein, inactive enzyme)
- tissue plasminogen activator (t-PA) is released from damaged tissue
2. plasmin (active enzyme)
3. digests clot
unwanted blood clots
-2 types
- embolus
2. thrombus
embolus
- type of clot
- definition
moving clot
-becomes stuck in a blood vessel and blocks circulation in that area
thrombus
-type of clot
stationary blood clot
anticoagulants
prevents unwanted blood clots