The Lymphatic System Flashcards
What are the functions of the lymphatic system?
- drains excess interstitial fluid
- transports dietary lipids from GI tract to blood
- protects against invasion through immune responses
- unwanted role in providing at least one pathway for spread of malignancy
What are the features of lymphatic capillaries?
flap like mini valve
most ECF is reabsorbed by the capillaries
pressure leaks out of them due to Starling’s Law
What aids lymph flow?
- Low pressure conduits
- Milking action of active skeletal muscle, numerous valves and pressure changes in the thorax (Deep lymphatics bundled in sheaths of CT with arteries – pulsations promote flow)
- Smooth muscle in walls of trunks and ducts contract rhythmically
Physical activity
What are the roles of lymph nodes?
- secondary lymph organs
- normally in groups
- filter lymph as macrophages remove and destroy microorganisms and debris
- activate the immune system as lymphocytes strategically located to monitor antigen presence
What does the right lymphatic duct do?
- drains right upper quadrant (right side of head, neck, thorax and right arm)
- duct drains into the junction between the internal jugular vein and subclavian veins (venous angle)
What does the thoracic duct do?
- drains rest of body
- begins in abdomen in cisterna chyle
- duct ends at left venous angle
What superficial drainage is there?
- cervical nodes drain above the clavicle
- axillary nodes between the clavicle and umbilicus
- inguinal nodes below umbilicus to drain to deep inguinal nodes
What lymphatic drainage is there in the head and neck?
efferent vessels enter superficial cervical lymph nodes along the course of the EJV over the SCM, into the deep chain
deep cervical nodes are vertical along the IJV with efferent vessels from the right jugular trunk
What are the main lymph nodes in the head and neck?
Preauricular, postauricular, parotid, submental, submandibular, supraclavicular, posterior cervical, anterior cervical, deep cervical, superficial cervical, occipital
What are the 2 groups of inguinal lymph nodes?
- horizontal (run superficial to the inguinal ligament, drain anterior abdominal wall, perineum and external genitalia excluding testes)
- Vertical (lie along termination of great saphenous vein, drain most of superficial lymphatics from leg)
Where do the efferents from inguinal superficial lymph nodes drain?
To the deep inguinal nodes: 3 nodes in the femoral canal, also receive lymphatics from deep structures of leg
What structures allow deep drainage of the thorax?
bronchomediatsinal trunks, bronchopulmonary nodes, interlobar lymph vessels, sub-pleural plexus, inferior trachea bronchial nodes, interpulmonary nodes, superior tracheobronchial nodes, tracheal nodes
What do Kerley B lines suggest?
Pulmonary oedema
What are the lymphatics of the posterior abdominal wall?
Lie along the aorta, IVC and iliac vessels
- external and internal iliac surrounded by lumbar lymph nodes and R. and L. lumbar trunks
- abdomen vessels surrounded by pre-aortic lymph nodes and intestinal lymph trunk
- intestinal and R. + L. lumbar trunks drain to cisterna chyle
How does the lymphatic system vary between infants and older adults?
Infants - lymphoid tissue increases to twice adult mass between 6-9 years then regresses through puberty, tonsils larger during childhood, immune response to infection is immature in first few months of life
Adults - number and size of lymph nodes decreases with age, some lymphoid elements lost, nodes more fibrotic and fatty than in young so impaired ability to resist infection
Which nodes are accessible for examination in the head and neck?
preauricular postauricular occipital tonsillar submandibular submental superficial anterior cervical deep cervical posterior cervical supraclavicular infraclavicular
Which nodes are accessible for examination in the arms?
axillary anterior axillary (pectoral) lateral (brachial) mid axillary (central) posterior (subscapular) Epitrochlear
Which nodes are accessible for examination in the legs?
superficial superior inguinal
superficial inferior inguinal
popliteal (occasionally)
What is the role of the spleen?
- site for lymphocyte proliferation, immune surveillance and response
- blood cleansing functions (extracts aged and defective blood cells and platelets, macrophages remove debris and foreign matter)
- stores/release breakdown products of RBC
- erythrocyte production In fetus
- stores platelets
What is the role of the thymus?
- secretes thymopoietin and thymosins causing T lymphocytes to become immunocompetent
- prominent in newborns continues to grow 1st year when highly active
- after puberty atrophy starts
What is the role of tonsils?
Different locations - palatine, lingual, pharyngeal, tubal
- gather and remove pathogens entering the pharynx in food or inhaled air
What are Peyer’s patches?
- large isolated clusters of lymphoid tissue located in the wall of distal small intestine
- lymphoid follicles concentrated in appendix wall which destroy bacteria and prevent pathogens breaching intestinal wall and generate memory lymphocytes for LT immunity
What is Starling’s Law?
Explains how fluid flows out of capillaries due to high hydrostatic pressure in capillaries ]#and then flow back into capillaries due to oncotic pressure (proteins)
How does lymph flow?
Lymphatic plexus -> lymphatic collecting vessels -> lymph nodes -> lymph vessels -> lymph duct -> venous circulation
What is the lymphatic plexus?
Collection of capillary and lymphatic vessels
What is lympathic filariasis?
Also called elephantitis
Parasitic worms get transported via mosquitoes that live in the lymph system.
It halts lymph absorption causing oedema
can cause scrotal hydrocele
What is the role of lymphatic trunks?
Drain lymphatic vessels and enter the R. and L. subclavian vein
Most trunks in pairs except for intestinal trunk is singular
What are the superior trunks?
L and R jugular
L and R subclavian
L and R bronchomediastinal (R forms right lymphatic duct and L forms thoracic duct)
What are the inferior trunks?
R and L lumbar trunks which are along the external and internal iliac
Intestinal trunk which form cisterna chyli -> thoracic duct
What is the role of the right lymphatic duct?
Drains upper right quadrants (ride side of head,
Where are cervical nodes?
Lie along the course of the EJV/over the SCM to then drain into the deep chain
What structures drain into the deep system?
thorax, abdomen, pelvis and perineum, head and neck nodes lie along IJV
What are the axillary lymph nodes?
Humeral, pectoral, subscapular lymph nodes drain into central nodes -> apical nodes -> supraclavicular nodes -> subclavian lymphatic trunk
What are the sentinel lymph nodes?
First node group that drain a tumour, removed to observe if the tumour has spread
What is Virchow’s node?
supraclavicular lymph node
if hardened - strong sign of cancer in the abdomen (often gastric cancer that has spread)
What are the main lymphoid organs?
Spleen Thymus Tonsils/adenoids Peyer's patches Myeloid tissue in bone marrow
