Thrombosis, embolism and shock Flashcards
Briefly describe what happens in haemostasis when there is an injury to a vessel.
After the injury the arterioles constrict and expose the extracellular matrix which attracts platlets which aggregate and then become active. The active platelets cause release of chemokines, sending signals to attract more platelets to the site and form a platelet plug.
The presence of which clotting factor catalyses the action of fibrinogen to fibrin?
Thrombin
How do we limit coagulation to the site of an injury?
Anticoagulents ciculating in the blood. e.g. antithrombins and plasmin
What affect does a high prothrombin time/INR have on clotting?
It reduces clotting
What is thrombosis?
A blood clot in vessels leading to a lump/mass of blood constituents.
What is the difference between a thrombus and an embolus?
Thrombus is a blood clot and an embolus is a piece of the blood clot that has broken free and is travelling through veins to somewhere other than the point of origin.
What are the 3 factors that promote coagulation?
- Abnormalities of blood vessel wall
- Abnormalities of blood flow
- Abnormalities of the bloods constituents.
Main locations where throbi can form
Heart, arteries, veins and capillaries
What can cause venous thrombosis?
A change in the flow of blood fom inactivity.
Immobility due to loss of function/op recovery.
Direct compression of veins.
3 things can happen to a thrombi, what?
1- can be broken down by fibrinolysis
2- converted into a scar by macrophages and fibroblasts, this narrows the lumen on the vessel.
3- the thrombi becomes detached and causes thromboembolism.
What are the causes of emboli?
Thrombus, fat, gas, tumour, infections, amniotic fluid and foreign bodies.
Arterial thromboembolism can cause what in the legs?
Acute ischaemia
What is a tumour material emboli?
When a tumour penetrates blood vessels and parts break off to fom metastases
In terms of an emboli what can happen if a uterus contracts very powerfully?
It can force amniotic fluid and squames from the infant into the veins of the mother to form an emboli.
What is shock?
When the organs and tissues are not recieving enough blood and oxygen supply and allows waste roducts to build up.
What are the clinical features of shock?
Low BP, tachycardia, really low or really high resps, low urine output, metabolic acidosis, hypoxia etc
What is compensated shock?
Non progressive and the blood volume loss is 15-25%
What is non-compensated shock?
Progressive and blood volume loss is over 25%
What is irreversible shock?
Failure to restore circulation and there is critical organ damage
What is hypovolaemic shock?
Haemorrage causes a sever amount of blood loss and the heart can’t pump enough around the body.
What is cardiogenic shock?
When your heart is suddenly uable to pump enough blood arount the body often caused by acute heart attacks.
What is septic shock?
When there is a significant drop in BP leadin to heart failure and failure of other organs. Caused by endooxins and infections.
What is anaphylactic shock?
A severe form of an alleric reaction.
What is neurogenic shock?
After damage to the CNS/spinal cord, low BP and slowed heart rate due to the disruption of autonomic pathways.
