Lecture 32: Lymphoid organs Flashcards
primary lymphoid organs
bone marrow, thymus
secondary lymphoid organs
lymph nodes, spleen, MALT
MALT
mucosa associated lymphoid tissue
- Diffuse populations of lymphoid cells in the mucosa
- Lymphoid follicles of the GI, respiratory and genitourinary tracts
- Peyer’s patches of the ileum
- Tonsils
sources from lymphocytes
bone marrow (ULTIMATE)
bone marrow makes
1) T cell precursor that goes to thymus where they mature into helper and cytotoxic
2) Mature B cells
* both end up in secondary lymphoids
what do helper t cells do
activate cytotoxic t cells
what to cytotoxic t cells do
- Kill tumor cells, virus-infected cells, etc by contact
- Cell-mediated immunity
what do b cells transform into
plasma cells
what do plasma cells do
Kill by secretion of antibodies
Humoral immunity
(FROM B CELLS!!!!)
where is thymus found
superior mediastinum
how many lobes to thymus
2
what happens to thymus at puberty
undergoes involutions
most active frombirth to puberty
function of thymus (3)
1) Provides an environment where T cell precursors proliferate, mature and acquire their immunocompetence.
2) Supplies mature T cells to secondary lymphoid organs.
3) Secretes hormone-like substances which stimulate T cell proliferation and maturation.
major cell types in cortex of thymus
large lymphocytes (immature T)
small lymphocytes (maturing T)
epithelial reticular
macrophages
clonal selection is another term for
maturation
