Exchange and the Lymphatic System Flashcards
Capillaries are specialised for
exchange
What cell type are capillaries composed of?
Endothelial
What feature of capillaries presents a small diffusion barrier?
Thin walls (one cell)
Other than thin walls, what feature of capillaries allows fast diffusion?
Large surface area
Give a distinguishing factor of fenestrated capillaries
Presence of large pores
What is the function of endothelial cell junctions?
To control which molecules leave the capillary
What type of capillary allows larger structures such as proteins and cells to leave?
Discontinuous
Capillaries are composed of one endothelial layer and
it’s concordant basement membrane
In what type of capillary are there no clefts or channels?
Continuous
In what type of capillary are there clefts and channels? (not massive channels)
Fenestrated
Fibrin monomers are cleaved from
fibrinogen
Fibrin monomers are cleaved by
thrombin
When the lining of a blood vessel breaks and endothelial cells are damaged, what fibres are exposed?
Collagen fibres
What component of the blood adheres to damaged endothelium?
Platelets
What is formed in the adherence of platelets to damaged endothelium?
Platelet plug
What is haemostasis?
The process of keeping blood inside a damaged blood vessel to stop bleeding
What happens to platelets when they stick together and to the proteins in the vessel wall which stimulates further platelet activation?
Platelets degranulate
If platelets alone are not enough to stop the bleeding from a vessel, what protein is released to strengthen the platelet plug?
Fibrin
What two substances act as chemical messengers and inhibit platelet aggregation and formation of the platelet plug?
Prostacyclin and nitrous oxide
What substance stops thrombin production?
Tissue factor pathway inhibitor (TFPI)
What substance binds and inactivates thrombin?
Thrombomodulin
What substances are expressed by TFPI to inactivate thrombin?
Thrombomodulin and Heparin
What is the function of plasmin?
To degrade blood clots
Why do cells have a lower concentration of oxygen than capillaries?
As cells are constantly respiring and using oxygen