Physioloical Thrombosis Flashcards
What is in the lumen of the artery?
Blood.
What cells line the lumen?
Endothelial cell.
Describe the structure of the lumen.
Stretchy as contains a lot of blood.
Anticoagulic.
what do endothelial cells it on?
Basal lamina or basement membrane.
this stops the cells from stretching too far.
What cells are around the basal lamina?
Smooth muscle cells.
wat are around the smooth muscle cells in blood vessels?
Interstital collagen fibres
What cells does the lumen contain?
Red blood cells
White blood cells
Platelets
.
What blood cell has a nucleus?
White blood cell.
What non-cellular components does the lumen contain?
Plasma (water and proteins)
What does plasma contain?
Clotting factors.
Where are clotting factors produced?
Liver
What kind of system are clotting factors part of?
Amplification system.
What is amplification system?
Clotting casacde- many more molecules of fibrin are compared to, for instance, TF.
What dpoes trauma lead to?
- Exposure of interstitial collagens (collagens in connective tissue between structures)
- Exposure of a molecule called Tissue Factor (=TF)
What does trauma result in?
Defects in vessels-
Blood leaks out and serum comes into contact with interstitial collagen fibres
When do plasma clotting proteins become activated?
When they come into contact w interstitial collagens
What is released from smooth tissue cells when activation occurs?
Tissue factor is released
After tissue factor is released, what can it do?
Tissue factor can now bind a particular clotting factor and initiate the clotting cascade
How do clotting factors become activated?
Cleave other clotting factors to form the active molecule
What does a clotting cascade lead to?
Clotting cascade leads to production of thrombin from prothrombin
What does thrombin converts soluble fibrinogen to?
insoluble fibrin
What is the endpoint of the clotting cascade?
production of insoluble fibrin strands that form a meshwork
Where are platelets produced?
Produced in bone marrow
From cell called a megakaryocyte
Define Megakaryocyte
Large cell w many nuclei
what happens in megakaryocytes in the bone marrow?
Undergoes nuclear division but not cell division so get huge cell with many nuclei
Where do platelets bud off as fragments from?
cytoplasmic extensions
How do platelets work?
Trauma to vessel exposure of platelets to interstitial collagen
Why do platelets join toegther?
Platelets adhere together try to form bridge to close gap
Define coagulation.
Solidification of blood
Name to the two types of coagulation
- Thrombus formation
- Clot formation
where does the formation of thrombus occur?
In flowing blood.
What colour is a pure thrombs?
Plae cream
Describe the structure of a thrombus.
A thrombus consists of platelets and a mesh like network of fibrin strands
Why does a thrombus of platelets and fibrin occur in flowing blood?
Platelets have molecules on their surfaces which allow adherence to interstitial collagen, even when blood is flowing past them – the clotting cascade deposits Factor VIII which enhances this further
Describe clot formation.
Blood leaks out off a vessel and becomes stationary (or stagnant
Whereabouts is the clotting cascade activated in clot formation?
Within the stagnant blood, sitting next to interstitial collagen
Describe the structure of a cloot.
Network of fibrin strands and red blood cells
tRauma to skin causes what to happen?
Every componant of blood leaks out.
This actiavtes the clotting system by collagen.
Then activated by stagnant blood which forms a clot.
What happens if the clotting system doesn’t work.
VESSEL VASOCONTRCITS T DECREASE BLOOD LOSS.
After vasocontriction, how will the platelets and fibrin thrombus reduce yet more blood loss?
A platelet and fibrin thrombus forms to bridge the gap between the ends of the vessel adjacent to flowing blood
When the skin has stopped beelding, waht process has been achieved?
Haemeostasis
Summarise howbleeding due to trauma can be stopped/
Vasoconstriction helps reduce bleeding
Clot formation occurs in space around vessel and may fill void of wounded tissue
Thrombus forms in flowing blood and stops bleeding from gaps in vessels
What can grow in the area of a wound?
New vessels = granulation tissue.
what do the capillaries which grown in the granulation tissue do?
They can oxygenate the area of the wound and keep it alive
How can a thrombus be removed?
A blood protein called Plasminogen converts to plasmin, and plasmin cuts up fibrin into smaller fragments, as a way of removing fibrin (in both clots and thrombi). In a thrombus this is sometimes called thrombolysis
How is the excess thrombus or clot removed?
By the fibrinolytic system which removes fibrin and stops thrombi from propagating
What does the fibrinolytic system dependant on?
-Plasma protein called plasminogen being converted to plasmin
-Plasmin cuts up fibrin into fibrin degradation products
What does plasmin do in fibrm?
cuts up fibrin in a thrombus.
what is the fibrinolytic system in balance with?
The clotting system.
What does palsmin generation at the site of injury do?
Plasmin generation, at the site of injury, limits the extent of the evolving thrombus
Name two times where thrombosis and blood clotting are normal.
- Wound healing
. Menstruation
What are the three mai causes of thrombosis?
Changes in the intimal surface of a vessel (we have discussed one example – that is when trauma occurs)
Changes in the pattern of blood flow
Changes in the blood constituents
