Phase 1 drive Cardiovascular notes- blood Flashcards
What is haematocrit?
Volume of red blood cells
What does it mean to be rhesus negative?
D antigen is not present
What is anaemia?
Reduced haemoglobin in the blood. (Lower than 12.5g/dL)
What is polycythaemia?
Higher than average haemoglobin levels
What is the lifespan of a neutrophil?
10 hours
What is prothrombin time?
How long it takes for blood to clot
What coagulation factors is vitamin K essential for the synthesis of?
2,7,9 and 10 can remember this as 1972
What protein in the blood plays the biggest role at maintaining oncotic pressure?
Albumin
In haemophilia, which clotting factor is there a deficiency of?
VIII (most common) or XI
Describe the mechanism of inheritance of Von Willebrands disease
Autosomal dominant
What does Von Willebrands disease result in?
A lack of vonwillebrand factor. Usually mild disorder
What could cause an acquired bleeding disorder?
Liver disease- site of clotting factor synthesis
Vitamin K deficiency- Vitamin K needed for synthesis of coagulation factors 10, 9, 7 and 2 (1972)
Drugs
Describe the solubility of vitamin K
Fat soluble
Describe the formation of the platelet plug
- Exposure of collagen fibres
- Platelets adhere to collagen via vWF. (adheres to vWF by GP1b)
- Platelets release their contents
- ADP is released which acts on P2Y1 and P2Y12, causing platelet amplification
- Thrombin binds to PAR1 and PAR4 receptors, inducing platelet activation and further thrombin release
- Platelet activation causes an increase in GPIIb/IIIa receptors which allow platelets to bind to other platelets with a bridge of fibrinogen inbetween
- Thromboxane A2 released from platelets and stimulates vasoconstriction and platelet aggregation
- Platelet plug contacts
Why doesn’t the platelet plug expand away from the damaged endothelium?
Undamaged endothelium secrete prostacyclin which inhibits platelet aggregation
Normal endothelium releases nitric oxide- vasodilator and inhibitor of platelet aggregation
What is the first plasma protein in the intrinsic pathway?
XII
What causes the activation of factor XII in the intrinsic pathway?
Contact with the exposed collagen fibres
What does XIIa catalyse the activation of?
factor XI
What does factor XI catalyse the activation of?
factor IX
What does IXa catalyse the activation of and what acts as a cofactor in this activation?
Catalyses the activation of factor X
Factor VIIIa acts as a cofactor
What does Xa convert?
prothrombin to thrombin
What is thrombin ?
the enzyme that converts soluble fibrinogen into insoluble fibrin
Where is tissue factor located?
On the outer plasma membrane of various tissue cells, including fibroblasts.
When the endothelial lining is damaged, the exposed tissue factor binds to which clotting factor?
Factor VII
What does the complex of tissue factor bound to factor VIIa go on to activate in the extrinsic pathway?
Activates factor X and factor IX
What clotting factors does thrombin contribute to the activation of in the intrinsic pathway?
XI, VIII and V
Which pathways is clotting usually initiated by?
The extrinsic pathway
What roles does the liver play in clotting?
Production of clotting factors
Produces bile salts for the absorption of vitamin K- lipid soluble. Vitamin K is needed for synthesis of several clotting factors
What is the function of plasminogen activators?
Covert plasminogen into plasmin
What does plasmin do?
Degrades fibrin
What platelet receptors does ADP bind to?
P2Y1 and P2Y12
What receptors on platelets does thrombin bind to?
PAR1 and PAR4
