Immune II Flashcards
describe MALT
mucosal-associated lymphoid tissue, nodules that are important in organs that are open to the external environment /high risk of pathogenic invasion
where are MALT cells found
digestive, respiratory, urinary, genital
what to MALT aggregates make
tonsils, appendix, peyers patches
describe MALT
unencapsulated, lack collagenous capsule (may be covered in flattened reticular cells)
2 major components of MALTS
- GALTS (gut associated lymphoid tissue)
2. BALTS (bronchus associated lymphoid tissue)
describe GALT
in small intestines as peyer’s patches, in lamina propria below mucosa, LYMPHOID NODULES FORM HALF CIRCLE (CLUMP)
describe Peyer’s patches
large, unencapsulated aggregates in walls of ileum, clumps/dozens of lymphoid nodules in lamina propria of mucosa and extends into submucosa
what cells cover peyers patches
simple columnar, follicle associated epithelium (FAE), contain microfold cells that can sample the antigen directly from the lumen
functions of peyer’s patches
- immune surveillance of interstitial lumen
2. facilitate immune response in mucosa
what do microfold (M) cells do
sample antigens directly from lumen
describe GALT in the appendix
surround entire lumen, goblet cells within epithelium, also has microfold cells, lymphoid nodules within lamina propria, NO VILLI
compare GALT in appendix and ileum
ileum has VILI with simple columnar epithelium and microvili, appendix has microvilli (simple columnar epi) but NO VILI
describe palatine tonsils
- covered in stratified squamous epithelium NOT KERATINIZED
- 10-20 CRYPTS
- numerous lymphatic nodules - GALT - B cells, plasma cells, macrophages, surrounding nodules are T cells
- band of dense CT separates tonsil from underlying tissue = barrier against spread of infections
describe lingual tonsils
- covered in stratified squamous epithelium NOT KERATINIZED
- SINGLE crypt
- numerous lymphatic nodules
- may see muscle and mucosal cells
describe pharyngeal tonsils
- covered by ciliated pseudostratified columnar epithelium
- NO CRYPTS
- lymphatic nodules
- thick respiratory folds, mucosa
describe lymph nodes
continuous encapsulated lympoid nodules, small but numerous, has cortex, medulla, capsule, afferent lymph vessels and efferent lymph vessels, blood capillaries/artery/vein in hilum
composition of cortex and medulla of lymph nodes
cortex: mostly B cells, nodules are here
paracortex: mostly T cells
medulla: lighter,macrophages, and plasma cells
medullary sinus: below medulla ans plasma cells and macrophages circulate here
describe capsule of lymph node
- dense CT, abundant lymphatics and vasculature
- subcapsular sinus containing lymph traveling through cortex
- cortex is deep
what cells are found in cortex of lymph node
reticular cells, macrophages, APC, lymphocytes, lymphoid nodules of mostly B cells, some secondary, have cortical sinuses between nodules to connect to subcapsular sinus
cells found in paracortex
mostly T cells, no lymphoid nodules and contains HEV (HIGH ENDOTHELIAL VENULES)
what are HEV
IN PARACORTEX OF LYMPH NODES, high endothelial venules, entry site for lymphocytes moving from blood into lymph node, have dome like projections with spaces where T and B cells squeeze in
contents of medulla
- medullary cords
2. medullary sinuses
composition of medullary cords
consists of mainly plasma cells and macrophages, plasma cells are resident and secrete Ab into circulation, branched extension of lymphoid tissue
composition of medullary sinuses
spaces separate medullary cords that contain reticular cells, fibers, lymph, lymphocytes, macrophages, ARE CONTINUOUS WITH CORTICAL SINUSES AND HILUM TO DELIVER LYMPH TO EFFERENT VESSELS
describe flow of lymph through node
flow into afferent lymphatic vessels into subcapsular sinus, into cortical sinuses, infiltrate between cortex and medullary cords, into the medullary sinuses into the hilum/efferent lymphatics
