Blood and Lymphatic disorders Flashcards
3 main functions of the blood
- distribution
- regulation
- protection
Distribution
- O2 and nutrients
- hormones
- metabolic waste
Regulation
- fluid volume
- body temperature
- ph in body tissues
- bicarb ions
Protection
- WBCs, antibodies to fight infection
- platelets and plasma prevent blood loss
haemeostasis
clotting cascade - coagulation
5 steps of haemostasis
- Vascular spasm
- platelet plug formation
- coagulation
- clot retraction and repair
- fibrinolysis
vascular spasm
injury to endothelium - release endothelin - contracts smooth muscle - pain and vasoconstriction
platelet plug formation
damaged endothelial cells - VWF released - binds platelets.
secretion of ADP, TXA2 & Seretonin
what do platelets bind together with
fibrinogen
what chemicals enhance vascular spasm?
TXA2 & Seretonin
2 parts of clotting cascade
Intrinsic and extrinsic
contact activation
Intrinsic pathway
tissue factor
extrinsic pathway
trauma activates clotting factor ..
VII into VIIa
extrinsic pathway
-15 secs to activate
- trauma
- direct trauma releases factor III
Intrinsic pathway
- slower (several minutes)
- damaged surface
- backs up extrinsic
fibrin mesh
both pathways end up here at factor Xa
what converts fibrinogen to fibrin
thrombin
what is a blood clot
combination of platelets and fibrin meshed together
platelet contraction
actin and myosin contract and pull damaged cells together
