0513 - thrombus, embolism, atherosclerosis

Question 1

what is meant by haemostasis

Answer 1

haemostasis is the balance in blood viscosity between thrombosis (which is the clotting of blood) and haemorrhage (which is too much fluidity).
this is essential to flow and clotting in response to injury.

Question 2

describe how coagulation occurs

Answer 2

answer

Question 3

how is thrombosis regulated

Answer 3

answer

Question 4

differentiate clot formation in venous versus arterial systems

Answer 4

answer

Question 5

what is atherosclerosis, why is it pathological

Answer 5

formation of inflammatory fibrous plaques with lipid core.

chronic inflammation and oxidised LDL which attracts heap of monocytes, which then eats stuff, resulting in a fatty streak.
smooth muscle cells move into due to cytokines, accumulation with collagen and proteoglycan leads to fibrous plaque.
calcification then happens.

atherosclerosis is dangerous as it can trigger arterial thrombosis. plaque rupture results in embolism

Question 6

describe what is meant by embolism

Answer 6

answer

Question 7

how is haemostasis different from thrombosis

Answer 7

in response to a cut, haemostasis starts sealing of blood vessel via platelet adhesion and fibrin deposition. thrombosis is where this goes overboard and the entire vessel is blocked.

Question 8

what are the steps involved in clotting

Answer 8

vessel injury leads to endothelial cells being exposed, and vasoconstriction. endothelial cells kicks off 1 factors which lead to platelet activation and aggregation, and tissue factor which activates the coagulation cascade, fibrinolytic system. all these lead to thrombosis.

Question 9

what are the key player in thrombosis

Answer 9

endothelium - Von W factor and tissue factor activation
platelets - adhesion to vWF, activation, release granules, aggregation at site to form plug
coagulation proteins - zymogens, purpose is to cleave fibrinogen to fibrin. fibrin becomes crosslinked to form clot structure.

coagulation inhibitors
fibrinolytic and antifibrinolytic pathways

Question 10

what are the intrinsic and extrinsic pathways of the coagulaiton system

Answer 10

extrinsic is dominant initiating factor - initiation (TF activates enzymes, prothrombin to thrombin, thrombin makes fibrinogen to fibrin. thrombin also feeds into intrinsic pathway)
intrinsic is positive feedback/amplification loop

Question 11

how is coagulation inhibited

Answer 11

thrombin activated Protein C and Protein S. these cleave factors V and VII
Antithrombin binds to thrombin to stop it working with heparin
TF inhibitors