10.3 Introduction to Lymphoid Organs Flashcards
What lymph nodes drain the lower limb?
- Popliteal (knees)
- Inguinal (pelvis)
Which sinuses does lymph first enter into within a lymph node?
Subcapsular sinuses
Primary vs secondary lymphoid follicles
Primary: no antigen encountered
Secondary: encountered antigen; plasma cells form distinct centre
Which cells are in the cortex/paracortex/medullary cords of a lymph node
Cortex: Mostly B
Paracortex: Mostly T
Medullary cords: plasma cells and macrophages
Which area of lymph nodes do immune cells first enter upon leaving the blood? Why?
Paracortex; this is where high endothelial venules are
Function of the spleen. What is the extra function in infants?
Spleen is responsible for:
- Recycling RBCs
- Removing particulate matter
- Produces immune responses
- Iron recycling
- Immune function
In infants, it is also responsible for haematopoiesis
Describe the components of the white matter of the spleen
- Periarteriloar lymphatic sheath (PALS; mainly T cells)
- Follicles (B cells)
- Marginal area/zone sepaartes two pulps (macrophages)
What types of lymphocytes are splenic nodules made of?
B cells
What % of the spleen parenchyma is red/white pulp?
75% red, 25% white
What is the red pulp of the spleen made of?
- Erythrocytes (make it red)
- Splenic sinuses
Describe the filtration of RBCs in the spleen
- Vessels exit central arterioles
- They have to squeeze through the reticular cells that make up splenic sinuses
- Once they have, they have proven themselves moveable enough to survive, and so they return to circulation
- But the clock is ticking: if they don’t make it back, they will be eaten up by macrophages or other immune cells
Role of red pulp vs white pulp
White: immune response
Red: Pulp acts like a filter
Where is the thymus located?
Retrosternal, level of the heart
