Thrombosis

Question 1

What is the structure of platelets?

Answer 1

Peripheral - rich in glycoproteins for adhesion
- contains plt factor 3 promotes clotting

Sol-gel
- contains microtubules, microfilments

Organelle
- contains alpha granules - factor VIII, V, fibrinogen, fibronectin
PDGF

Membrane
- Dense tubular system for platelet contractile functions and prostaglandin synthesis

Question 2

What simulates thrombus formation

Answer 2

Exposure to endothelial collagen and fibrin

Results in adhesion of platelets to vessel endothelium

Question 3

What stimulates platelet aggregation? Inhibits?

Answer 3

Thromboxane A2 stimulates

Prostaglandin I2 inhibits

Question 4

What is Virchows triad

Answer 4

1. change in nature of blood flow
2. change in the vessel wall
3. change in the constituents of blood

Question 5

What can happen once a thrombus is formed?

Answer 5

Detach from teh vesssel wall froming an embolus
Lysed by plasmin
Persist at the vessel wall to form an occlusive thrombus - recanalisation can occur through an occlusive thrombus
form a mural thrombus covered by smooth muscle cells which become vascularised

Question 6

What is protein C

Answer 6

Vitamin K dependent protease that inhibits Factors Va and VIIIa

Question 7

How is protein C deficiency inhertied?

Answer 7

Autosomal dominant

Clinically affected are heterozygous with aprotein C conc of 50%

Question 8

What is factor V leiden

Answer 8

Resistance of factor V to bearkdown by protein C

Question 9

What is protein S

Answer 9

Cofactor in inactivation of factor Va and VIIIa by protein C

Ineritance of deficiency is autosomal dominance

Question 10

What is antithrombin III

Answer 10

Inhibitor of activated coagulation factors inc thrombin factor 9a and 10a

Question 11

What is an embolus

Answer 11

Mass of material carried in the bloodstream which finally impacts in the lumen of a vessel

May be solid, fluid and gas

Question 12

What is the process of atheroma formation

Answer 12

Endothelial cell damage
Platelets adhere to endothelium
Smooth muscle cell prolfieration in intima

PDGF stimulates

Intracellular and extracellular lipid accumulates at the site due to breakdown in the endothelial cell barrier

Fibrolipid plaque formed

Question 13

What are complications of atherosclerotis plaques?

Answer 13

NEcorsis and softening of the plaque base resulting in aneurysm formation due to thinning adventitia

Small plaque fissures can lead to microthrombi and larger fissures can lead to emobli

Question 14

What are risk factors for atherosclerosis?

Answer 14

Smoking, HTn, DM, Hyperlipidaemia

Age
Male
Sex

Question 15

What lipoproteins are protective

Answer 15

High HDLs