major lymphatic trunks include:
lumbar (paired), bronchomediastinal (paired), subclavian (paired), jugular trunks(paired) and intestinal trunk (single)
lymphatic collecting vessels
- three tunics as veins
- vessels have thinner walls than veins more internal valves
larger collections appear in the — of mucous membranes and lymphoid organs
lamina propria
lymphatic trunks join to form two lymphatic ducts:
right lymphatic duct and thoracic duct
afferent lymphatic vessels
lymph enters these nodes
peyer’s patches
- isolated clusters of lymphoid tissues
- found in the wall of the distal portion of the small intestine
- similar structures are also found in the appendix
- peyer’s patches and the appendix destroy bacteria, prevent them from
invading the intestinal wall - generate “memory” lymphocytes for long-term immunity
at the base of the palate – commonly removed
palatine tonsils (paired)
is much larger than the right lymphatic duct. It serves the left atrium, left side of head and neck, abdomen and lower extremities
thoracic duct
thymus
- T-lymphocytes to become immunocompetent cells
- densely packed lymphocytes scattered macriphages
- star-shaped thymocytes secret thymosins and thymopoietins that
stimulate lymphocytes to become immunocompetent
if lymph nodes are overwhelmed by large numbers of antigens, they
become inflamed and tender
buboes (swollen glands)
at the base of the tongue – may also be removed
lingual tonsils (paired)
in the nasopharynx
pharyngeal tonsil (single)
they derive from monocytes and phagocytize foreign substances and
help activate T cells
macrophages
lymph vessels include:
microscopic, permeable, blind-ended lymphatic capillaries; lymphatic collecting vessels; lymphatic trunks and lymphatic ducts
- main cells involved in the immune response
- are T cells B cells
- B cells are transformed into plasma cells, which secrete antibodies
lymphocytes
there are fibroblast like cells that produce a fibrous network to support other cell types in lymphoid organs
recticular cells
tonsils
- formed by the aggregation of lymph nodes
- associated with the production of
lymphocytes and antibodies - crypts trap and destroy bacteria
drains the right arm and the right side of the head, neck and thorax
right lymphatic duct
area containing mostly lymphocytes on reticular fibers and
involved in immune functions
white pulp
spleen
- served by the splenic artery and vein, which enter and exit at the
hilus - site of lymphocyte proliferation, immune surveillance and response
- cleanses blood and stores breakdown products of RBCs
- site of fetal erythrocyte production (normally ceases after
birth) - stores blood platelets
lymphoid organs
bone marrow, lymph nodes, spleen, thymus, and tonsils
lymphatic capillaries
- capillaries are remarkably permeable as endothelial cells are
loosely connected - endothelial cells allow interstitial fluid to enter lymph capillaries
but don’t allow lymph to escape from the capillaries - mini valves
- during imflammation, lymph capilliaries absorb cell debris, pathogens, cancer cells etc.
- lacteals are specialized lymph capillaries present in intestinal mucosa that absorb digested fat and deliver to the blood
interstitial fluid once it enters lymphatic vessels
lymph
