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
lymph node: network of sinuses/ flow
irregular channels through lymph node, contain reticular fibres, lymphocytes, macrophages
afferent lymphatic vessels –> subcapsular sinus –> trabecular sinuses –> medullary sinuses –> efferent lymph vessel (hilum)
features/ function: lymphatic nodules
small, egg shaped mass of lymphatic tissue without capsule
- found in lamina propria of mucous membranes of digestive, urinary, reproductive, respiratory systems
- mucosa-associated lymphoid tissue (MALT)
aggregations of lymphatic nodules:
tonsils, Peyer’s patches
features/ function: tonsils
incompletely encapsulated lymphoid tissue
at junction of oral cavity , oropharynx and nasal c. and nasopharynx
- palatine
- pharyngeal
- lingual
immunity: general definition
body has system of cells which can distinguish self from non-self (foreign substance)
immune responses provide defence of body against invasion from
- outside: bacteria, virus etc.
- inside: abnormal cells
cells of immune system and distributed how:
lymphocytes, plasma cells, mast cells, neutrophils, eosinophils, phagocytic cells
- blood
- lymph
- epithelial tissue
- connective tissue
features/ function: antigen
molecule capable of inducing immune response/ production of antibodies
can be:
- protein
- polysaccharide
- bacteria
- protozoa
- virus infected cell
- tumor cell
2 types of responses to antigens:
humoral:
- immunoglobulins (antibodies Ab) secreted by plasma cells are involved in response
cellular:
- lymphocytes are involved
features: antibody
glycoprotein, in immunoglobulin protein family (Ig)
classes of antibodies:
IgG, IgA, IgE, IgD, IgM
function/ action of antibodies:
neutralisation, opsonisation, complement system activation, cytotoxicity
two types of immunity: general
innate: present from birth
adaptive (acquired/ specific)
innate immunity:
fast, non specific, no memory
- skin
- mucous membranes
- phagocytic cells (macrophage, neutrophils, monocytes, natural killer cells)
adaptive immunity:
more efficient, high specific, has memory, activation of B/ T lymphocytes to destroy invading organisms
