ch 20 lymphatic system/lymphoid tissues p2 Flashcards
primary lymphoid organs
red bone marrow/thymus
where B and T cells mature (correspond to name)
secondarylymhpoid organs
lymph nodes, spleen, mucos associated lymphoid tissue (MALT)
where mature lymphocytes first encounter antigens and get active
most important secondary lymphoid organ
lymph nodes
where do lymph nodes form clusters
axillary, cervical, inguinal regions. this is where large number of collecting lymph vessels converge to form lymphatic trunks.
why are lymph nodes important
activate immune system and cleanse lymph via filtration
HOW DO lymph nodes activate immune system
dedritic cells bring antigens to lymph nodes to put shit on display and active T cells in lymphocytes
how to lymph nodes cleanser lymph with filtration
lymph passes through nodes before it enters back to circulation and macrophages clean lymph
why are lymph clusters extremely important
allow lymph to travel through multiple lymph nodes, so likelihood of pathogen being recognized is high and before getting to heart
lymph node compartments
corte, medulla in dense fibrous bean capsule
cortex of lymph node
outer node portion, outer contains dense follicles wit dividing B cells and inner iw mostly T cells
medulla of lymph node
inner node portion, B and T here
lymph sinus
sites where macrophages reside
afferent lymphatic vessels
there are several, bring the lymph into the node (arrives). lymph circulates through sinuses.
efferent lymphatic vessels
allows lymph to leave node, lymph enters a node faster than it can leave, so lymph remains in node. little longer. efferent exits
why is it good to leave lymph in node slightly longer
ensures lymph is cleaned out before it exits fully, and increases cleansing function so more likely to see a pathogen if it is there
lymphadenopathy
NOT swollen glands, nodes are overhwlemd and blocked due to much infection, they are swollen, tender, pus filled. usually necessitates antibiotics to assist in treatment. pus will wall off infection site so it wont travel
secondary cancer sites
metastasizing cancer cells break free from original tumor, and get stuck in lymph nodes in other body parts. they get swollen and enlarged but no pain. example is axillary nodes swell indicating breast cancer.
spleen
RBC recycling plant, largest lymphoid organ, very well vascularized. cleanses the blood! may also store iron for later, or platelets and monocytes.
how does spleen cleanse blood
pulls old damaged blood cells from blood supply and macrophages will pull microorganisms from blood.
red pulp of spleen
recycling center, erythrocyte and pathogen destruction. packed with rbc and macrophages
white pulp of spleen
serves immune function, mostly lymphocytes on reticular fiber
can u bleed to death of spleen ruptures
yes if it is severe, if spleen lost bone marrow and liver take over functions, 20% have a secondary spleen.
mucosa associated lymphoid tissues (MALT)
found in mucous membranes, make it easy for pathogens to come in- but MALT prevents entrance to the areas
3 main MALT areas
tonsils, Peyer’s patches, appendix
tonsils
at entrance to pharynx in throat, fights infections and bacteria coming in from mouth
types of tonsils
palatine- largest, most likely to become infected. strep
lingual- lymphoid follicles at base of tongue
adenoids- in posterior wall of nasopharynx (nose meets pharynx)
tubal- surround openings of auditory tubes into pharynx. ear infection
Peyers patches and appendix
aggregated lymphoid nodules, similar to tonsils but found in ileum wall (where small intestine joins large) protects small
appendix has a large concentration of lymphoid follicles
both of these above organs are good for preventing bacteria at small intestine e and generates memory lymphocytes
general lymphocytes
a lymphocyte that remembers a pathogen
thymus
primary lymphoidnorgan for T cell maturation. needed for maturity of them otherwise body defense wouldn’t exist
where is the thymus most active
infants or toddlers, it atrophies into early adolescence. immune cells are then put out reduced rate. replaced with fatty tissues and does nothing. this sets up immune system to be strong for life
cortex
packed tightly with lymphocytes, maturing T lymphocytes
medulla
has fewer lymphocytes and has hassells corpuscles, regulate T cell productions. helps it not attack what it should not
thymosin
thymus hormone that stimulates development of mature T cells, and stimulates immunocompetencey. this is when T cells can distinguish fro, our cells and not good ones.
why is the thymus different from other lymphoid organs
no B cells in thymus, no direct immune response (only T cell maturation site not immune response) (, no reticular fibers (instead has epithelial cells that are ideal for T cell maturation).
thymus is basically
School for T cells!
