Section II: The Lymphoid System Flashcards
What are the peripheral lymphoid organs
sites where lymphocytes are gathered to contact antigens
-lymph nodes, spleen, appendix, tonsils, and adenoids
What is the lymphoid system
collection of tissues and organs that are strategically designed and located to bring the population of B cells and T cells into contact with any and all antigens that enter the body
What are the primary lymphoid organs
Where hematopoietic stem cells that will become T and B cells mature
What are lymphatic vessels
flow within lymphoid system occurs via vessels that carry lymph, which is collected from the fluid that bathes the bodys tissues
What are lymph nodes
- connected by lymphatic vessels
- store and circulate lymphocytes
- germinal center contains dividing lymphocytes
- lymph flows through nodes to remove particles before returning to circulation
What is the spleen
- Functions to filter blood and destroy old erythrocytes
- lymphocytes produced in white pulp, while red pulp filled with blood
- many macrophage present that phagocytize erythrocytes and cell debris
What is MALT
Mucosal-Associated Lymphoid Tissue
- diffuse system of small concentrations of lymphoid tissue found in various sites of the body such as the gastrointestinal tract, thyroid, breast, lung, salivary glands and eye
- Most recognizable are tonsils and peyers patches
What is SALT
Skin-Associated Lymphoid Tissue
-collection of lymphocytes under the skin
Where do immature lymphocytes mature
They mature and become committed to a particular antigenic specificity within primary organs. Only after maturation is a lymphocyte immunocompetent
What is the Thymus
- responsible for immunogenesis in children
- location of maturation of T lymphocytes
- Produces hormone thymosin
What is thymosin
functions in the preprocessing of T cells and development of B cells to plasma cells
Compare the child thymus vs the adult thymus
Thymus is large and active in children with peak size being seen during puberty. Replaced with fat as age
What is Thymic education
the differentiation of thymocytes (immature T cells)
What do thymocytes develop into
- CD4 T cells (helper)
- CD8 T cells (cytotoxic)
What are CD4 T cells
- subpopulation TH-1 induce cell mediated immine response
- subpopulation TH-2 activate B cells to produce antibody
