Lymphatics Flashcards
(37 cards)
Embryology
Mesoderm: Lymphatic vessels, LN, the spleen, myeloid tissues
Endoderm: thymus and parts of the tonsils
Physiological Function
Major role in numerous homeostatic mechanisms of the body: Immune, digestive, fluid balance, waste
Spleen
Location: beneath ribs 9-11 on the left, abuts diaphragm
Characteristics: Largest single mass of lymphoid tissue, pressure-sensitive-movement of the diaphragm drives splenic fluid movement
Function: Destroy damaged and deformed RBC, synthesize Igs, clear bacteria
Liver
Location: RUQ; palpable at R costal margin
Characteristics is pressure sensitive like the spleen
Function: half of the body’s lymph is formed, clears bacteria, gate-keeper of the hepatobiliary-pancreatic venous and lymph drainage
Thymus
Location: Anterior mediastinum
Characteristics: Development, larger in infacy and size peaks at 2 y/o. After puberty involutes, replaced by fatty tissue
Function: Site of maturation of T cells
Tonsils
Location: 3 types all located in the posterior oropharynx
- Palatine-lateral pharynx
- Lingual-Posterior 1/3 of tongue
- Pharyngeal-Adenoids at nasophyangeal border
Characteristics: Most are not visible until 6-9 months of age, remain enlarged thru childhood
Function: Provide cells to influence and build immunity early in life, nonessential to adult immune function
Appendix
Location: Proximal end of the cecum
Characteristics: Contains lymphoid pulp
Function: Part of the GALT
Visceral Lymphoid Tissue
GALT:
Peyer’s patches-ileum
Lacteals-Lymphatic capillaries of small bowel
Pulmonary lymphoid tissue scattered, filters toxins from lungs
Lymph FLuid
Substances that leak out of the arterial capillaries into the interstitium get taken up by lymphatic capillaries
-Fluids, proteins, electrolytes, and cells
Fluid Balance
30 L of fluid move from capillaries to interstitial space each day
-90% to capillaries and 10% to lymphatic system
When fluid overload occurs, lymphatic system helps prevent tissue dps by clearing the excess
OMT and Lymphatic Drainage
35-60% of the drainage thru the thoracic duct is associated with respiration
-Pump effect of the diaphragmatic crura on the cystena chyli
Restrictions of lymphatic flow must be first drained thru the associated terminal area
Normal Lymph Flow
Lymph channels begin a blind endothelial tubes or capillaries compose d of a single layer of leaky squamous epithelium that is supported by anchoring filaments
Lymph Vessel Anatomy
Lymphatic capillaries–>collecting lymphatics–>afferent lymphatic vessels–>efferent lymphatic vessels–>thoracic duct or R lymphatic duct–>venous system
Run with veins
ECF is sucked in by the low level negative pressure
Lymphatic Collectors
Consist of primarily of chain of muscular units called lymphangions
Possess two-leaflet bicuspid valves
Work like pacemakers, contracting regularly throughout the lymphatic system and moving lymph in peristaltic waves
Path of Lymph Flow thru a LN
Afferent lymphatics–>Subscapsular Space–>Outer cortex–>Deep Cortex–>Medullary sinus–>Efferent Lymphatics
Lymph Nodes
Most highly organized lymphoid tissue, dispersed along the course of lymph vessels
Types: superficial and deep
Function: Filtration of lymph fluid, maturation of lymphocytes, phagocytosis of bacterial and cellular debris
Virchow’s Node
L supra-clavicular, GI cancer
Epitrochlear Nodes
Secondary syphilis
Thoracic duct
Master lymph vessel: drains L head/neck, LUE, L thorax/abs, Everything umbilicus down
Origin at cisterna chyli (Distal dilation at L1-2, receives lumbar lymphatics)
Pierces Sibons facscia at superior inlet, U-turns to empty into L subclav/IJ veins
Right Lymphatic Duct
Origin: From the junction of R jugular and subclavian trunks (and occasionally the bronchomediastinal trunk)
Termination: Empties at R subclav/IJ venous junction
Function: Drains R head/neck, RUE, R thorax
Purification and Cleansing
Lymph fluid bathes organs
Cleanses extracellular spaces of particulate matter, toxins, bacteria, cellular waste, and post-injury biochemical by-products.
Nodes act as filters
Defense
Lymph fluid brings toxins, bacteria, and viruses into contact with the organized lymph tissues
- High concentrations of immune cells
- APCs and maturation of immune cells
Free flow of lymph fluid is necessary
Nutrition
Fat absorption via chylomicrons
-Too big to cross capillary intercellular junctions, travel via lacteals->larger lymph vessels->thoracic duct->venous system
Returns proteins to the vasculature
SNS Effects Lymph Valves
Increased sympathetic tone–>Tighter valves–>Decreased lymph flow into the venous system
