Lymphatic system Flashcards
what general parts make up the lymphatic system:
lymph, lymphatic vessels, lymphoid organs/ tissues
components of lymphatic vessels:
capillaries, lymphatic vessels, ducts, trunks
components of lymphoid organs/ tissues:
primary:
- red bone marrow
- thymus
secondary:
- spleen
- lymph nodes
- lymphatic nodules
general functions of lymphatic system:
- drains excess interstitial fluid
- transports dietary lipids/ lipid soluble vitamins
(carries out immune responses)
general flow of lymph:
interstitial fluid (lymph) –> lymphatic capillaries –> lymphatic vessels –> lymphatic trunks –> lymphatic ducts –> veins
general features: lymph vessels
- thin walled
- have valves
- similar in structure to veins
- lymph nodes (along lymph vessels)
location: lymph trunks
lumbar, intestinal, bronchomediastinal, subclavian, jugular
two lymphatic ducts:
- left lymphatic duct (thoracic duct)
- right lymphatic duct
what areas are drained: L lymphatic duct
- L side of head/ neck/ chest
- L upper limb
- whole body inferior to ribs
- drains: junction of L internal jugular and L subclavian veins
what areas are drained: R lymphatic duct
- upper R side of body (inc. head, neck, chest)
- R upper limb
- drains: junction of R internal jugular and R subclavian veins
what pumps help lymph flow:
- skeletal muscle pump
- respiratory pump
lymphedema: eg
swelling of tissue due to insufficient functioning of lymph system
- retention of fluid
features/ function: red bone marrow
- main site of haematopoiesis
- pluripotent cells give rise: erthrocytes/ leukocytes
- B Lymphocytes mature in bone marrow
- T Lymphocytes migrate to thymus -> immunocompetent
features/ function: thymus
- bilobed organ: superior mediastinum btw sternum/ aorta, surrounded by thin capsule
- fully functional at birth, matures at puberty, involutes
- site of T Lymphocyte maturation
- rich blood supply
features/ function: thymic lobule cortex
- peripheral, dark zone
- site of proliferation/ maturation of T Lymphocytes
- dendritic cells, specialised epithelial cells (thymic hormones)
- most T cells die via apoptosis
thymic lobule: main parts
cortex and medulla
features/ function: thymic lobule medulla
- central, light zone
- mature T cells
- dendritic, epithelial, cells, macrophages
- Hassall’s corpuscles: epithelial cells become filled with keratin, degenerate, calcify
- more with maturity
features/ function: spleen
- left hypochondriac region (btw 9-11) ct. capsule
- invaginates into spleen forming trabeculae
- superior/ visceral surface
s: convex- diaphragmatic
v: visceral- gastric, renal, colic impressions
Hilum: splenic artery and vein, lymphatics, sympathetic nn.
parts: parenchyma of the spleen
white pulp
red pulp
parenchyma of the spleen: white pulp
- lymph tissue around branches of splenic artery, central artery
- immune function (B T cells) destruction of pathogens
parenchyma of the spleen: red pulp
venous sinuses/ cords of splenic tissue -> splenic (Billroth’s) cords
- removal of old blood cells and platelets, storage of platelets, site haematopoiesis (foetal life)
function: spleen
- mounts primary immune response,
- filtering blood,
- destruction of blood cells
- storage of platelets
- production of erythrocytes (foetal)
not essential for life
Splenomegaly: eg
enlargement of spleen
features/ function: lymph nodes
small encapsulated organs located along pathway of lymphatic vessels
- small bean shaped, filters
- widely distributed throughout the body but concentrated in:
axilla, inguinial, mesenteries
