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Lymphatic System/Immune System:
- overview
- structural components: lymphatic vessels, lymph, lymphoid cells, tissues, organs
- functions: transports lymph (maintains normal blood volume), produces, maintains and distributes lymphocytes
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lecture notes
- Functions:
- produce maintain and distribute lymphocytes: primary lymphoid structures contain stem cells(bone marrow and thymus) secondary lymphoid structures activate immature lymphocytes and cause them to divide. (lymph nodes and tonsils)
- maintain blood volume and eliminate variations in the ISF: end of a systemic capillary is 35mmHg thus the end of a lympatic is 35 mmHg. lymphoid system returns the same amount of interstitial sluid to the blood stream.
- Alternate route for hormones nutrients and waste:
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Lymphatic Vessels:
- interstitial fluid vs lymph
- lymphatic capillaries: comparison to blood capillaries, endothelial cells overlap and are anchored down (one-way swinging door)
- lymphatic collecting vessels: similar to veins in structure but with more internal valves, superficial and deep
- lymphatic trunks: lumbar, bronchomediastinal, subclavian, jugular, intestinal, similar to veins in structure
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lecture notes
- called lymphatics
- range from lymphatic capillaries to ducts (like blood vessels)
- Lymphatic capillaries: 1) larger in diameter 2)have thinner walls (lack basal lamina) 3)flat or irregular outline 4) have collagenouse anchoring filaments to keep vessels open 5) have overlapping fenestrated endo thelial cells that act as a 1 way valve
- lacteals from intestines transport lipids
- bone marrow and CNS have not lymph vessels as there are no blood vessels
- lymphatic valves give the vessels a beaded appearance
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lymphatic ducts:
- right lymphatic duct: collects lymph from right side of body above the diaphragm, returns to venous circulation at the junction of the right internal jugular vein and subclavian vein
- thoracic duct: collects lymph from both sides of the body below the diaphragm and from the left side above the diaphragm, returns to venous circulation at the left subclavian vein near junction with the left internal jugular vein
- cisterna chyli: the lower bulged section of the thoracic duct that collects from regions below the abdonmen pelvis and lower limbs via R and L lumbar trunks and intestinal trunks
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lecture notes
same as above
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Lymphoid Cells:
- macrophages (phagocytic cells)
- lymphocytes - “T” cells, “B” cells, “NK” cells
- “T” cells (cell mediated immunity): cytotoxic T cell, helper T cell, suppressor T cell, memory T cell
- “B” cells (antibody mediated immunity): plasma cells, memory B cells
- “NK” cells (natural killer cells)
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lecture notes
- T Cells: 80%. cytotoxic t cells attack foregin cells, helper t cells and suppressor t cells help regulat the immune response, memory t cells are targeted cells on reserve
- B Cells: 10-15%. mature into plasma cells, that secrete anti bodies which bind to antigens. aka immuno globulins. memory B cells are made after infected and always carry the antibody associated with that virus
- NK Cells: 5-10%. attack foregin cells infected cells and cancer cells
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Lymphoid Tissue:
- reticular connective tissue: macrophages, lymphocytes
- diffuse lymphatic tissue
- lymphatic follicles or nodules: tightly packed spheres of reticular tissue and cells, germinal centers (B cells)
- found in lymphoid organs and in isolated aggregates in
- other areas: digestive system (GALT), pharynx as tonsils (pharyngeal, palatine, lingual tonsils), ileum (Peyer’s patches), appendix
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lecture notes
- pharyngeal tonsils: superior wall of nasopharynx
- palatine tonsils: posterior margin of oral cavity between the pharynx and soft pallate
- lingual tonsils: located at the base of the tongue
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