Lymphoid tissues Flashcards
Why is the lymphoid system vital?
Despite the abundance of T cells and B cells due to their specific TCR or BCR receptors it is unlikely the cells could detect threats around the whole body.
Where does lymphopoieses occur?
Primary lymphoid organs are where lymphocytes are produced.
Name some primary lymphoid organs?
Bone marrow
Thymus
Foetal Liver
What are the hallmarks of the adaptive immune system?
Specificity – provided by a vast range of unique T cell and B cell receptors
Memory – rapid expansion in response to secondary encounter
What is the primary site of haematopoiesis?
Bone marrow
White cell production increases during infection
* in foetus : All bones \+ liver/spleen in adults : Mostly flat bones,Vertebrae Iliac bones Ribs, Ends of long limb bones
The B cell “repertoire” is generated in the bone marrow
Where does final maturation happen?
Final maturation occurs in the periphery
Where do thymocytes go?
Immature T cells migrate from the bone marrow to the thymus (Thymocytes)
What is the positive and negative selection for select for T cells?
Positive selection – can the T cell receptor signal
Negative selection – does it react against our own body
What is thymus involution?
the shrinking of the thymus with age. Associated with a change in structure and a reduced mass.
Name some secondary lymphoid organs?
Spleen Lymph nodes Appendix Mucosal associated Lymphoid tissue
How do the arterial and venous connections in the spleen aid the lymphocytes?
Filter blood antigens quickly ( carry pathogens ) past distinct T and B cell zones in the spleen
What are Peyer’s Patches?
Specialized secondary lymphoid tissues within the gut - Found below the epithelium of the ileum of the small intestine.
Lots of active B cells - allowing for mutation and selection of B cell antibodies
- get alot of microbial antigens in the gut so alot of B cells
Follicles surround the Peyer’s Patches and connect to afferent lympathics. What does it contain?
highly enriched with B cells, and contains a high frequency of germinal centres.
What are Germinal centres?
Germinal centre: anatomically restricted site where B cells undergo mutation and selection to generate high affinity antibodies
What encircles the oral and nasal cavity to form the Waldeyer ring?
Pharyngeal, tubular, palantine and lingual tonsils encircle the oral and nasal cavity – form the Waldeyer ring
- Pathogens pass by this very often, they contain germinal centres and lymphoid follicles