Thrombosis

Question 1

Define Thrombosis

Answer 1

Formation of a solid(or semi solid) mass from constituents of circulating blood (leads to formation of a thrombus which is the mass so formed)

Question 2

Define clot

Answer 2

Formation of a solid mass in blood which is not circulating e.g. in a test tube/after death

Question 3

List stages in the evolution of a thrombus

Answer 3

A thrombus is a blood clot that forms inside a blood vessel. It can block the blood flow and cause serious problems. The formation of a thrombus involves four main steps:

1. 1.Primary platelet thrombus (porous platelet plug)

Platelets stick to the damaged vessel wall and form a loose plug.

2. . Haemostatic plug

Fibrin, a protein that helps blood clot, joins the platelets and makes the plug stronger and denser. The plug has layers of platelets and fibrin, and some blood cells trapped inside. The fibrin can contract and make the plug bumpy.

3.Occlusive thrombus

The plug grows bigger and starts to slow down the blood flow. It can eventually fill up the whole vessel and stop the blood flow completely.

4. Propagation of thrombus

The plug breaks off from the vessel wall and becomes a clot that can travel in the bloodstream. The clot is made of platelets, fibrin, and blood cells. It can get stuck in another vessel and cause damage to other organs..

Question 4

List factors predisposing to thrombosis

Answer 4

Vessel wall
Blood Flow
Constituents of the blood

Question 5

List possible consequences of thrombi

Answer 5

2 effects Local vs Distant
1.Local
-venous
Stagnation of blood flow, congestion and oedema. If there is complete cessation of venous return from an organ
-Arterial
.Complete arterial occlusion Leads to progression of the ischaemia on the organ supplied to infarction.

Distant
thrombus may detach and form an embolus

Question 6

Classify specific types of venous thrombi

Answer 6

Deep veins
Superficial veins
Renal veins
Intracranial veins
Portal/mesenteric veins
Hepatic veins