Lymphatics Flashcards
Lymphatic System Functions
Drain excess Interstitial Fluid
Transport dietary lipids
Protect against invasion
Unwanted role in providing pathway for spread of malignancy
What happens if 3L interstitial fluid not reabsorbed
Oedema
Components of lymphatic system
Lymph- 3L of IF that circulates
Lymphatic capillaries
Lymphatic vessels –> drain into trunks–> into ducts in venous system
Capillaries wall
Single wall
Porous membrane
Capillaries composition
Endothelial cells
Have loose flap arrangement
Permeable to hormones, fats + proteins found in ISF
Anchored by collagen filaments in interstitium
ECF reabsorption
Most ECF reabsorbed by capillaries
Approx 17L/day
Capillaries absorption MOA
When pressure in interstitium increases, flaps open –> allow influx of ISF
If pressure decreases, the flap closes
Lacteals
Specialised lymphatic capillaries
Found interspersed within the villi in the intestines
Help fatty molecules that cannot access the capillary bed to be absorbed
–> transported into venous system
Lymphatic plexus
Collection of lymphatic vessels within the capillary bed
Widen to become lymphatic capillaries
Flow of lymph
Lymphatic collecting vessels –> lymph nodes (filter lymph)–> drain into lymphatic trunk –> drain into lymphatic duct –> venous system in neck
Elephantitis (Lymphatic filariasis)
Roundworm larvae transported by mosquito
Hide within lymphatic system + obstruct vessels within lymphatics
Lymph can’t drain into venous system
Tissues begin to swell
Elephantitis complication
Scrotal Hydrocele
Lymphatic vessels pressure
Low pressure conduits
Aiding flow of Lymph
Musculo-venous pump Valves to prevent backflow Pressure changes in thorax Pulsations Smooth muscle in walls of trunks + ducts
Musculo-venous pump
Milking action of active skeletal muscle
Pressure changes in thorax
Pressure decreases in thorax –> vessels dilate –> flow of lymph
Deep lymphatics
Bundles in sheaths of CT with arteries
Pulsations of artery –> help promote flow of lymph
Inferior Lymphatic trunks
Lumbar trunks
Intestinal trunk
Lumbar trunk
Drain fluid from legs
Intestinal trunk
Drain fluid from intestines, spleen + liver
Superior Lymphatic trunks
Bronchomediastinal trunk- joining of smaller trunks
Subclavian trunks
Jugular trunks
Right Lymphatic Duct
Terminal end of lymphatic system on RHS
Drains at junction of internal jugular vein + right subclavian vein
Drains R Upper quadrant (right side of head, neck, thorax + right arm)
Thoracic Duct
Drains rest of body
Begins in abdomen as cisterna chyle
Duct ends at left venous angle in venous system
Lymph nodes
Only structures that can filter lymph
–> macrophages remove + destroy microorganisms + debris
Unfiltered lymph journey
Enters lymph nodes through afferent lymphatic vessels
Dendritic cells (APC) detect pathogen if present in lymph
Present antigen to B lymphocytes
B lymphocytes produce antibodies
Antibodies in lymph neutralize pathogen
T lymph attack antibody tagged pathogen
Superficial nodal components
Drains the skin
All eventually drain into deeper nodes
Cervical nodes
Drain lymph above clavicle
Vessels enter along course of External Jugular Vein
Axillary nodes
Drain lymph between clavicle + umbilicus
Inguinal nodes
Drain lymph below umbilicus
Deeper nodal components
Drain structures of thorax, abdomen, pelvis + perineum
Deep cervical nodes
Vertical chain along Internal Jugular Vein (posterior to SCM)
Efferent vessels form right and left jugular trunks
Palpable lymph nodes
Submental Submandibular Tonsillar Parotid Preauricular Posterior auricular Occipital Superficial cervical Deep cervical Supraclavicular
Nodes that drain into central nodes
Humeral nodes (arm) Pectoral nodes (anterior chain) Subscapular nodes
Central nodes
Generally palpable in apical (infraclavicular) nodes
Drain into apical (infraclavicular) nodes
Apical nodes
Drain into supraclavicular nodes
Axillary nodes lymph journey
Humeral + Pectoral + Subscapular nodes –> central nodes –> apical nodes –> supraclavicular nodes –> subclavian lymphatic trunk –> right (or left) venous angle
Sentinel lymph nodes
First nodes/groups of nodes along route of tumour/infection spread that will collect inflammatory products or products from tumour itself
Breast exam
Can take biopsy
Radioactive dye injected around area
Probe follows its course in sentinel node
Sentinel node removed + analysed
Radical Mastectomy
If sentinel node removed contains tumorous material, must remove nodes in that region as precaution
Breast tissue removal + lymph node removal
–> reduces lymphatic vessels/area for fluid can return to lymph system –> lymphoedema
Lymphoedema from radical mastectomy
Can take up to 12 months to progress due to disruption of flow in lymph system
Approx 20% of patients will have
Lymph drainage abdomen (below umbilicus) + lower limb
2 groups of superficial inguinal lymph nodes which are palpable (horizontal + vertical)
Horizontal lymph nodes
Run superficial to inguinal ligament
Superficial lymphatics from anterior abdominal wall, perineum + external genitalia (excluding gonads)
Para-aortic nodes
Drain gonad lymph
Vertical lymph nodes
Lie along termination o great saphenous vein
Drain majority of superficial lymphatics from leg
Deep inguinal nodes
Efferents from superficial lymph nodes drain into here
Not palpable
Also receive lymphatics from deep structures of leg
Efferents to external iliac nodes
Vertical + Deep Inguinal lymph node clearance
Cancerous lymphatic fluid has retracted from sole of foot
Has presented in both vertical + horizontal superficial lymph nodes
Inguinal lymph node clearance during surgery to remove malignant melanoma
Deep drainage of thorax
Subpleural plexus –> interlobar lymph vessels
And other nodes
Interpulmonary nodes
Within lung tissue itself
Bronchopulmonary nodes
Nodes at junction of lungs + bronchus
Inferior tracheobronchial nodes
Receive from the heart
At junction of trachea + bronchus
Superior tracheobroncal nodes
Above carina
Paratracheal nodes
Along sides of trachea
Posterior mediastinal node
Associated with aorta
In close association with tracheobronchial nodes
All nodes in lungs etc
Drain into bronchomediastinal trunks
External and internal iliac nodes
Common iliac nodes
Lumbar lymph nodes
R + L lumbar trunks
Vessels from abdomen
Pre-aortic lymph nodes
Intestinal lymph trunk
Cisterna chyle
Dilation that marks beginning of thoracic duct
Located anterior to L1 and L2
Intestinal + R + L lumbar trunks drain into here
Virchow’s Node/ Trosier’s Sign
Supraclavicular nodes on LHS
Associated with gastric cancer, and cancers in abdomen
Receive drainage from abdomen
Infants + children
Lymph tissue increases to 2x adult mass between 6-9 yo, then goes back to adult level by puberty
Tonsils larger during childhood
Older adults
No. + Size of lymph nodes decreases with age
Nodes more fibrotic + fatty –> impaired ability to resist infection
Thymus lost
Lymphoid organs
Only lymph nodes filter lymph, even if tissue make up of lymphoid organs (excluding thymus) is reticular connective tissue Spleen Thymus Peyer's patches of intestine Tonsils/Adenoids Myeloid tissue in BM
Spleen
Behind stomach
Filters blood
Provides site for lymphocyte proliferation, immune surveillance + response
Blood cleansing functions
Extract aged + defective blood cells + platelets
White pulp spleen
Lymphocytes (immunity)
Red pulp spleen
Macrophages to clear up debris
Spleen function pt 2
Stores/releases breakdown of RBCs
Stores platelets
Lot of lymphoid tissue can congregate around splenic artery
Spleen in foetus
Involved in haemopoiesis
Left hemidiaphragm
Stomach + spleen
Thymus location
Inferior neck + superior thorax deep to sternum
Thymus function
Secretes 2 polypeptides which cause differentiation + maturation of T cells
- -> thymopoietin
- -> thymosins (cause T lymphocytes to become immunocompetent)
Thymus growth
Prominent in newborns
Continues to grow 1st year when highly active
After puberty starts to atrophy
Tonsils
Create ring-like structure which trap pathogens which are ingested or inhaled
Receptor mediated immune response
Tonsil names
Named according to location Palatine Lingual Pharyngeal (adenoids if enlarged) Tubal
Peyer’s patches
Large isolated clusters of lymphoid tissue in wall of distal SI
Lymphoid follicles also concentrated in wall of appendix
Peyer’s patches MOA
Destroy bacteria –> prevent pathogens from breaching intestinal wall
Generate memory lymphocytes for long term immunity
