IMM - Lymphoid tissue Flashcards
Lymphatic system
Made of lymphatic vessels and secondary lymphoid tissue
Lymphoid tissue
Primary/secondary/tertiary
Primary lymphoid tissue
Where lymphocytes (B/T/NK) are produced - lymphopoieses
Primary lymphoid organs
Bone marrow/thymus/foetal liver (8-10 weeks after gestatio?)
B and T cells
Comprise adaptive immune response which is SPECIFIC (range of unique T/B receptors) - builds immunological memory
Infection
White cell production increases
In children
Haematopoiesis in foetus - liver is primary organ for this (ALL bones)
Adults
Bone marrow production in vertebrae/ribs
T cell terminal differentiation
They migrate from bone marrow site into thymus
Which bone marrow produces blood cells?
RED bone marrow
Repertoire
Range of genetically different BCRs or TCRs present in a given host ; greater the repertoire more diverse can recognise a greater variety of threats
B cell repertoire
Made in bone marrow - final maturation in periphery
What type of T cells move from bone marrow to thymus?
Immature - thymocytes
T cell selection
Positive selection - does it recognise antigens via their TCR - can the TCR signal
Negative selection - does it react against out own body and get very activated to self antigens
Thymus cortex/medulla
Medulla below cortex ; medulla is lighter than cortex
Thymus decline?
With age - shining/reduction in mass ; thymic involution reduced output of T cells
T cell vs t cell repertoire
3.75*10^11 t cells
TCR repertoire ; genes allow for between 10^15/10^20 - how does small pop of cells find a antigen in the body
Secondary lymphoid tissues
Where lymphocytes can interact with antigens and other lymphocytes
Secondary lymphoid organs
Lymph nodes
Tonsils
Spleen
Appendix
Mucosal associated tissue
How are lymphoid tissue distributed
Interconnected via lymphatic system and blood
Discrete organs
Lymph nodes/adenoids
(or can be part of an organ like the spleen for example)
Lymph node structure
Look at pic
Afferent lymphatic vessel and efferent so the lymph fluid is drained (not blood via arterial/venous connection)
Germinal centre
B cells undergo rearrangement so they are better at secreting antibodies
On the outside lymph nodes
Lymphoid follices (b cell area)
Inside area (after yellow circles of germinal centre)
t cell area
Spleen
Filters blood for antigens (only the red pulp part of the spleen)
Gut associated lymphoid tissue
Specialised tissue called Peyer’s patches and found below epithelium of the ileum of the small intestine ; follicle highly enriched with germinal centres - home to largest community of microbiota
Tonsils
Oral antigens are detected - forms the waldeyer ring
Where are SLO particularly located?
Barrier surfaces like the lungs/skin/GI tract
Lymphatic network
Lymphatics drain fluid from around the body and bring large volume of molecules through SLO
Purpose of lymphatic network
Immune cells including lymphocytes and antigen bearing dendritic cells to migrate to and from sites of inflammation to lymph nodes
B/T cells
Constantly recirculate round every 24 hours rather than just being static in the SLO
When inflammation
Lymph nodes closest to site of inflammation will send out signals to retain B/T cells
