Exchange and Lymphatic System Flashcards
What is the gross structure of capillaries?
Lots of them, thin walled and a small diameter
Where in the body would you find continuous capillaries with no clefts or channels?
Brain
What are the two mechanisms involved in clotting?
Formation of a platelet plug and formation of a fibrin clot
How does stopping blood contacting collagen and producing prostacyclin and NO prevent clotting?
There is no platelet aggregation
What effect does tissue factor pathway inhibitor have on blood clotting?
It stops thrombin production`
What effect does thrombomodulin have on blood clotting?
It binds to thrombin and inactivates it
What effect does heparin have on blood clotting?
It inactivates thrombin
What effect does tissue plasminogen activator have on blood clotting?
It activates plasminogen to plasmin which digests the clot
What are the main features of diffusion?
It is self-regulating, non-saturable and allows non-polar substances to cross the membrane
How do polar substances cross the membrane by diffusion?
Through clefts and channels
How much plasma is lost through the capillary beds each day and where does it end up?
3L which enters the lymphatic system and is returned to the heart
Which pressure pushes fluid into the capillaries from the ECF?
Osmotic (oncotic) pressure
Which pressure pushes fluid out of the capillaries?
Hydrostatic pressure
Besides veins, what other time of vessel has valves?
Lymphatic vessels
What is oedema?
Accumulation of excess fluid
