Cardiovascular Pathology 1

Question 1

What forms a haemtostatic plug

Answer 1

Platelets
Fibrin
Red blood cells

Question 2

How is a haemostatic plug formed?

Answer 2

Endothelial injury leads to adhesion and aggregation of platelets
Platelets adhere to collagen by vWF and RBC becomes enmeshed with the platelets forming a loose platelet plug
At the same time, exposure of tissue factor initiates the coagulation cascade forming insoluble fibrin stabilising the loose plug

Question 3

Fibrinolysis

Answer 3

Ensures the haemostatic plug does not become too big
Fibrinolysis is activated by the same injury that initiates haemostasis
TPA cleaves plasminogen
Plasmin is formed and this breaks down insoluble fibrin to soluble products

Question 4

Thrombosis

Answer 4

Inappropriate activation of haemostasis which overwhelms the capacity of the fibrinolytic system leading to a solid plug-thrombus
This is pathological

Question 5

Clot vs. Thrombus

Answer 5

Both are made from RBC and fibrin, but thrombus also have platelets
Clots: Forms outside cardiovascular system and in stationary life
Thrombus: Forms within the cardiovascular system and flowing blood

Question 6

Virchow’s Triad

Answer 6

Endothelial Injury
Abnormal blood flow
Hypercoagulability

Question 7

Causes of endothelial injury

Answer 7

Atherosclerosis
Vasculitis
Direct trauma e.g. heat, chemical injury

Question 8

Causes of abnormal blood flow

Answer 8

Turbulence:
Atherosclerosis, artificial valves, stents, implanted devices
Stasis:
Recent surgery, trauma, immobilisation, pelvic obstruction

Question 9

Causes of hypercoagulability

Answer 9

Too many blood cells:
Erythrocytosis, thrombocytosis
Coagulation factor defects:
Hereditary e.g. Factor V Leiden, prothrombin mutation
Acquired: DIC, active cancer, anti-phospholipid syndrome

Question 10

Most important risk factor for thrombosis in an artery

Answer 10

Atherosclerosis

Question 11

Most important risk factors for thrombosis in a vein

Answer 11

Stasis and hypercoagulability

Question 12

Complications of Thrombosis

Answer 12

Partial occlusion of the vessel at the site of thrombosis
Complete occlusion of the vessel at the site of thrombus
Embolism to a distant site

Question 13

Modifiable risk factors for developing atherosclerosis

Answer 13

Smoking
Hypertension
DM
Dyslipidemia

Question 14

What happens to damaged endothelial cells?

Answer 14

They become dysfunctional
Increased permeability
Produce adhesion molecules and cytokines which attract inflammatory cells and prothrombotic molecules
e.g. VCAM-1 binds monocytes and T cells

Question 15

What happens when inflammatory cells are recruited?

Answer 15

Monocytes and T cells adhere to the endothelium and migrate into the intima
Monocytes differentiate into macrophages

Question 16

What effects do the macrophages have?

Answer 16

Produce free radicals that drive LDL oxidation to form oxidised LDL