Lymphatic drainage Flashcards
What is the purpose of the lymphatic system?
To remove excess interstitial fluid and to act as a site for immune cell proliferation, development and storage.
Why does capillary permeability vary along its length?
Due to the changes in hydrostatic and oncotic forces. Hydrostatic is highest at the arteriole end.
What is the CV function of the lymphatic system?
Not all fluid that leaves the capillaries is reabsorbed so it is taken up by lymphatic vessels to rejoin the circulation at the SCV
Why will oedema result during infection?
Filtration is slowed by the increase in blood cells, increasing blood volume, creating a greater hydrostatic pressure. Vascular permeability also increases during an immune response so more fluid will move into the tissues.
Why might ischaemia result from the oedema?
If the ECF increases due to the oedema and the skin becomes too far away from vessels for diffusion if will become ischaemic.
What is the immune function of the lymphatic system?
To recognise, remove and present foreign antigens as well as proliferating immune cells when APC arises.
What is the structure of a lymphocyte?
No cytoplasm, large nucleus and has a large surface area due to projections
What is a lymph node?
An endothelium lined sinusoid that contains macrophages and lymphocytes. Has both a cortex and a medulla
Where does the afferent and efferent vessels enter/leave?
Multiple afferent lymphatic vessels enter into the subcapsular sinus around the node, the fluid is cleaned and then the efferent leaves at the hilum alongside the nodal artery and vein.
What is lymphangitis?
An infection occurring when the lymph can’t be cleared
How does cellulitis occur?
When an infection meets a node it can spread throughout the body and cause an infection of the deeper layers of the skin and underlying tissue.
What do aggregations of lymph nodules form?
MALT - mucosal associated lymphatic tissue e..g. tonsils, payer’s patches and appendix. They are used for filtration, presentation and replication.
What is bone marrow?
A lymphoid organ responsible for the production of lymphocytes.
What is the spleen composed of and what is its function?
Red pulp (80%) seperated by White pulp. The red pulp forms the secondary lymphoid tissue. It contains arterioles surrounded by lymphoid sheaths called PALS, that contain T cells. The red pulp filters the blood to remove RBCs through the fenestrated sinusoids to macrophages.
Where is the spleen located?
Between the left 9-11th rib in the peritoneal cavity
