Pathology - Circulation Flashcards
What lines the lumen of blood vessels?
endothelium
What is around the basal lamina of blood vessels?
smooth muscle
What is around the smooth muscle in blood vessels?
interstitial collagen fibres
What does the lumen of blood vessels contains?
- red blood cells
- white blood cells
- platelets
- plasma
What does plasma consist of?
water, proteins, other solutes
What does plasma contain?
clotting factors
Where are many clotting factors mainly produced?
in the liver but also by endothelial cells
What are clotting factors?
an amplification system, resulting in thrombin production
What does thrombin do?
converts soluble fibrinogen into insoluble fibrin
What does fibrin do?
forms a mesh of strands
Simplified clotting cascade
damage → TF + prothrombin → thrombin + fibrinogen → fibrin
What is meant by initial damage in the clotting cascade?
one obvious is trauma
What does trauma lead to?
- exposure of interstitial collagens (collagens in connective tissue between structures)
- exposure of a molecule called tissue factor (TF)
What is tissue factor released from?
smooth muscle
What does “many clotting factors are serine proteases” mean?
that clotting factors have a serine amino acid in them and they cleave other clotting factors to form the active molecule
Where are platelets produced?
in bone marrow from a cell called megakaryocyte
What is a megakaryocyte?
large cell with many nuclei
How do platelets work
trauma to vessel → exposure of platelets to interstitial collagen → platelets adhere together and try to form bridge to close gap
What is coagulation
Solidification of blood (clotting)
What are the 2 types of coagulation
- Thrombus formation
2. Clot formation
Where does thrombus formation occur
In flowing blood
Pure thrombus
- Pale cream coloured
- Consists of platelets and a mesh like network of fibrin strands
What is thrombosis
The process of thrombus formation
Why does a thrombus of platelets and fibrin occur in flowing blood?
platelets have molecules on their surfaces which allows adherence to interstitial collagen ever when blood is flowing past them - the clotting cascade deposits factor VIII which enhances this further
Where does clot formation occur?
Blood leaks out of a vessel and becomes stationary (stagnant)