40 - Immunological homeostasis. Organs Flashcards
What is immunological homeostasis?
Homeostasis - ability of organism to reg int environment in stable constant condition
Immunological homeostasis
- Develops in evolution, carry genetic uniqueness of organism
- recog, bind and remove foreign molecules, cells, bacteria, other products, chem substances (pollen, drugs, food etc)
What is immune defense
complicated homeostatic mechanism for recognition - self/non-self consisting of specific and nonspecific
factors of the immunity
What is the difference of primary and secondary lymphoid organs and what are they?
Primary - where lymphopoiesis occurs
BM and thymus
Secondary - sites of immune reaction, immune proliferation and specific immune response
Spleen, LN, MALT
Describe location and structure of thymus
Location: antsup mediastinum, posterior to sternum and sup to heart
Size greatest at birth the atrophy w/ age
2 lobes divided up into many lobules
- outer, more darkly staining cortex (highly cellular) - immature thymocytes and macrophages
- inner lighter staining medullar (less cellular)
- outer CT capsule and sept - epithelial cells, DC, hassal’s corpuscle
TSC - thymus stromal cells
- TSC interact with thymocytes directly by
adhesion molecules.
- TSC secrete various cytokines and thymus
hormones.
TEC - thymic epithelial cells - hormones and cytoking secr, interact between cells directly
Thymocytes
- secretes various cytokines.
ECM
Active substance
Fct of Thymus
1)Development and differentiation of T
lymphocytes
2) Immune regulation of the thymus
3) Barrier function of the thymus
1) Immature lymph accumulate in embryo 90-100 post fert (initiall yolk + liver > BM). BM > BTB > thymocytes > cortex > meddul - learn self/nonself (foetal + short time post birth) > mature periph T cell > periph BV > 2o organs
98% die, greatest production before puberty
Failure of thymus development
digeorge synd
T cell deficiency but norm B cell
BM fct
- generation of all immunocytes (initially yolk sac and para aortic mesechyme) and differentiation
- maturation of B cell + specific cells in
2o immune response. - generation of all circulating blood cells in the adult from HSC
- Contain Ab secreting plasma cells from periph circ
Myeloid precursors -> phagocytic monocytes
Lymphoid precursors -> take part in cell mediated kil
Processes are controlled by GF and IL and CSF
Antenatal HSC are transformed into В-Ly in the fetal liver.
Spleen
left side thorax under rib
DCT capsule w/ trabeculae divid into lobules
Parencyma
- white pulp - L cells resideperiarterial LN (predom Tlymph-Thymus dependent zone) and lymph follicles (B lymp-Thymus indep zone)
- red pulp
- marginal zone
Spleen fct
filter blood - remove old RBC Immune - Ag stim B and T diff Haemopoiesis Blood resevoir Site of Ab synth > circ Capture foreign Ag from blood > spleen + macrophage and DC bring Ag Major site of phagocytosis of Ab coated bacteria B cell comlete maturation after leave BM
LN structure
DCT capsule - pierced by vessels draining into marginal sinus > medullary sinus > efferent lymph vessels
- Cortex - thymus dependent and independent zone - mainly V
- Paracortex - mainly T lymph
Medulla - B lymph, pl, mac
MALT
Defenf org from ag directly penetrating mucosal surface
Non capsulated - diffuse lymphoid tissue and large germinative centres w/ B ly
inc tonsil - waldheyers ring, peyers patches ( submucosa of SI - 2o large follicles of B-ly w/ dispersed between smaller T-ly areas
Other unencapsulated lymphois tissue
Salt
urogen
conjunctiva
