Exchange and the Lymphatic System Flashcards
What is the gross structure of capillaries?
Specialised for exchange
Every tissue is within 100μm of one
Thin walled
Small diameter
What are the parts of the ultrastructure of capillaries?
Endothelia cell junctions
Transcytosis vesicles
Pores/fenestrations
Basement membrane
What are the 3 main ultrastructures of capillaries in the body?
Continuous
Menstruated
Discontinuous
Where are continuous capillaries found?
No clefts or channels - brain
Clefts only - muscle
Where are discontinuous capillaries found?
Liver - clefts and massive channels
Where are fenestrated capillaries found?
Intestines - clefts and channels
What does clotting involve?
Formation of a platelet plug and a fibrin clot
What is the process of the anti-clotting mechanisms of the endothelium?
Stops blood contacting collagen
Produces prostacyclin and nitrogen oxide
Produces tissue factor pathway inhibitors
Expresses thrombomodulin
Expresses heparin
Secretes tissue plasminogen activator
What is bulk flow?
The movement of particles into and out of vessels because of hydrostatic and osmotic pressure
What forces particles out of vessels?
Hydrostatic pressure
What forces particles into vessels?
Osmotic pressure
What happens to the 3l of blood volume that is not accounted for in the blood vessels?
It is taken up by the lymphatic system
What is oedema?
Accumulation of excess fluid
What can cause oedema?
Lymphatic obstruction
Raised central venous pressure
Hypoproteinemia
Increased capillary permeability
Where does filtration happen in the lymphatic system?
In the lymph nodes
