A&P: Lymphatic System Flashcards
Main function
Maintain blood volume
Lymphatic capillaries
Take up excess fluid
Smallest
Weave between tissue cells and blood capillaries in loose CTs of body
Drain into collecting vessels
Collecting vessels
Have valves (unidirectional flow) 3 Tunicas
Trunks
Largest of lymphatic vessels unite
Drain large areas of body
Dump lymph into right atrium
Collect lymph from collecting vessels
Ducts
Dump fluids into venous blood –> superior vena cavae –> right atrium
Right lymphatic duct
Drains lesser part of body (Right upper limb, right side of head and thorax)
Thoracic duct
Drains everything else
Cisterna chyli: beginning of thoracic duct
Collects lymph from 2 large lumbar trunks and intestinal trunks
Function of lymphatic vessels
Return excess tissue fluid to bloodstream
Return leaked proteins to blood
Carry absorbed fats from intestine –> blood
Lymph
Filtered blood
Lymph nodes
Clean/filter lymph before it is returned to circulation
Cluster along lymphatic vessels
Surrounded by fibrous capsule with internal trabeculae
Located at sites where lymphocytes encounter antigens and are activated to mount response against them
Filtration: enters afferent, exits efferent
Immune cells
Lymphocytes
Macrophages
Dendritic cells
Lymphocytes
B and T cells
Arise in red bone marrow
Macrophages
Phagocytes
Help to activate T cells
Dendritic cells
APCs
Present foreign antigens to other immune cells
Supporting cells
Reticular cells: produce reticular fiber stroma (network that supports other cells in lymphoid tissue)
Lymphoid follicles
Clusters (All except thymus)
Areas where immune cells are proliferating
Tightly packed lymphoid cels
Reticular fibers dominate organs
Germinal centers
Middle part of lymphoid follicles
Proliferation of B cells
Thymus
Specific for T cells Shrinks as you age Secretes thymic hormones Thymosin THF TF Thymopoietin No follicles (lacks B cells) Made of epithelial tissue
ONLY lymphoid organ that does not directly fight antigens
T lymphocytes precursors are kept isolated from foreign antigens to prevent premature activation
Primary lymph organs
Organs where lymphocytes become immunocompetent
Bone marrow: maturation site for B cells
Thymus: maturation site for T cells
Spleen
Largest
Lymphocyte proliferation
Surveillance and response
Stores platelets and monocytes (blood-rich)
Blood-cleansing
Removes aged and defective blood cells and platelets
Stores breakdown products of RBCs for later use
Fe: taken out of circulation
Site of erythrocyte production in fetus
Red pulp and white pulp
Red pulp
Destroys/recycles RBCs
Stores monocytes
Stores platelets
Vast majority of spleen
White pulp
Immune function
Made mainly of lymphocytes
Proliferation of B and T cells
MALT
Mucosa-associated lymphoid tissue Diffuse/scattered lymphoid tissue (located in mucous membranes) Tonsils Peter's patches Appendix
Tonsils
Ring of lymphoid tissue around the entrance to the pharynx
Peyer’s Patches
More numerous towards distal end of small intestine (Ileum)
Aggregated lymph nodules
Clean before substances pass to large intestine
Appendix
Beginning of large intestine
Destroys bacteria before they an breach the intestinal wall
Generates memory lymphocytes for long-term immunity
Buboes
Large, swollen, tender to the touch, infected lymph nodes
Lymphangitis
Structure or lymph vessel becomes inflamed and squeezes own blood supply from vasa vasorum –> blood pooling
Lymphedema
Localized swelling
Lymphatic capillaries are obstructed/blocked and cannot take in lymph
Lymphatic filariasis
Elephantiasis
Parasitic worm transported by mosquitos, where they reproduce in lymphatic vessels
