Week one, lymph system, innate immunity Flashcards
What are the two funtions of the lymphatic system?
Fluid handling and immune surveillance
How does the lymphatic system “handle fluid”?
It returns components of the blood that were filtered out of the capillaries and into the interstitial space back into the blood systemic circulation.
These components include: Fluid, solutes and proteins
Describe how lymph moves through lymph nodes, and what the lymph encounters along the anatomic structures of the node.
Afferent vessels enter the node with lymph, delivering it to the subcapular space, where it meets macrophages and dendritic cells.
Lymph flows then into the outer cortex which contains B cells within germinal centers.
Then lymph enters the deep cortex to encounter T cells.
It continues into the medullary sinus at the core of the lymph node. This area is rich with B cells and plasma cells.
Finally, efferent lymphatics leave the lymph node at the hilum.
Generally, how does lymph differ from blood serum, in terms of its components?
The electrolyte composition is roughly the same.
Total protein is almost half for lymph compared to serum. The same is true for albumin and IgG. Cholesterol is also much lower in lymph.
Which three forces determine fluid exchange at the level of the capillary bed?
- Net hydrostatic pressure
- Net oncotic pressure
- capillary filtration (permeability of the capillary membrane)
What determines net hydrostatic pressure?
(Picture a soaker hose for this process)
Blood pressure and peripheral resistance. It is stronger at the arteriole end of the capillary bed and weaker at the venous end. (This is capillary hydrostatic pressure)
Also at play is the slightly negative interstitial hydrostatic pressure.
Both of these pressures drive fluid out of the capillaries.
What drives oncotic pressure at the capillary bed?
Proteins in the blood exert osmotic pressure to pull fluid back into the blood, as the blood is rich in proteins compared to the interstitial space.
