2.5 Lymphatics Flashcards
Who first described the lymphatics system and when?
Olaf Rudbeck (Sweden) in 1653
When did AT Still emphasize that diagnosis of the fascia and treatment of the lymphatic system was vital for maintaining health and treating disease?
1874
Who and when was Applied Anatomy of the Lymphatics published?
1922: Frederic Millard DO
When does lymphatic development begin? Significant?
5th week of gestation; 20 weeks
From which structures do lymphatic structures arise?
- Mesoderm - lymph vessels, lymph nodes, spleen, myeloid tissue
- Endoderm - thymus and parts of tonsils
When does lymphoid tissue increase until? what happens at this point?
puberty (roughly around 6-9 years)
- immune system matures, but lymphoid tissues slowly regress until 15-16 years
–Stable throughout adult lifespan
What happens to the immune system in geriatrics?
declines, may not mount a fever
What are the anatomic components of the lymph system? (3)
- tissues/organs: spleen, liver, thymus, tonsils, appendix, visceral lymphoid tissue, lymph nodes
- lymph fluid
- lymphatic vessels
What are the physiological functions of the lymphatic system? (4)
- immune
- digestive - nutrition
- fluid imbalance
- waste
Spleen: location, characteristics, function
-location: beneath ribs 9-11 on left, next to diaphragm
normally not palpable
- characteristics: largest single mass of lymphoid tissue, fluid movement driven by diaphragm movement
- functions: destroy damaged/deformed RBCs, synthesize Igs, clear bacteria
Liver: location, characteristics, function
- location: RUQ; palpable at R costal margin
- characteristics: movement of diaphragm important for movement of fluids
- function: half body’s lymph formed here, clears bacteria, “gate keeper” of shared hepato-billary pancreatic venous and lymphatic drainage
Thymus: location, characteristics, function
- location: anterior mediastinum
- characteristics: large in infancy and peaks at 2 yo, involutes after puberty and replaced by fatty tissue
- function: maturation of t cells, little or no function in adults
Tonsils: location, characteristics, function
- location: 3 types in posterior oropharynx: palantine (lateral pharynx), lingual (posterior 1/3 tongue), and pharyngeal (adenoids at nasopharyngeal border)
- characteristics: not visible until 6-9 mo, remain enlarged through childhood
- function: provide cells to influence and build immunity early in life, nonessential to adult immune function
Appendix: location, characteristics, function
- location: proximal end of the cecum (large intestine)
- characteristics: contains lymphoid pulp, atrophies with age
- function: part of GALT
What are examples of GALT (gastrointestinal association lymphoid tissue- visceral lymphoid tissue)?
- Peyer’s patches (ileum)
- lacteals (lymphatic capillaries of small bowel)
What is lymph fluid and what is is made of?
Substances that leak out of the arterial capillaries into the interstitium get taken up by lymphatic capillaries b/c of leakier junctions;
immune cells, foreign antigens, bacteria and viruses, clotting factors, chylomicrons post-prandial
How much fluid moves from capillaries to interstitial space each day? to where?
30 L
90% to capillaries, 10% to lymphatic system
½ of diffused plasma proteins re-enter system via lymph
What is the lymph role in purification and cleansing?
• bathes organs
• Cleanses extracellular spaces of particulate matter, toxins, bacteria, cellular waste products, and post-injury biochemical by-products
• Fluid then travels from vessel to node
–Node acts as purifying filter
How much drainage through the thoracic duct is associated with respiration?
35-60%
What tissues do not have lymphatic vessels?
- epidermis
- endomysium
- cartilage
- bone marrow
What do the lymph channels begin as? What are they composed of?
blind endothelial tubes/capillaries of single layer of leaky squamous epithelium supported by anchoring filaments.
What are the path of the lymphatic vessels? (8 structures)
- Terminal lymphatics: Interstitial space of tissues
- collecting vessels
- afferent lymph vessels
- lymph node(s)
- efferent lymph vessels
- lymphatic trunks
- thoracic duct or right lymphatic duct
- venous system
What are lymphagions?
chains of muscular units that possess two-leaflet bicuspid valves that contract regularly throughout the system and move lymph along in peristaltic waves
What is the afferent lymphatics?
channel that delivers lymph to the node from the peripheral tissues on the side opposite the hilum
What is the subcapsular space of a lymph node?
a meshwork of reticular fibers, macrophages, and dendritic cells where afferent vessels deliver lymph
What is the outer cortex of a lymph node?
rich in B cells that sit within germinal centers that resemble those of lymphoid nodules
What is the deep cortex of a lymph node?
contains lymph sinuses dominated by T cells
What is the medullary sinus of a lymph node?
located at core, region rich in B cells and plasma cells
What is the efferent lymphatics of a lymph node?
channel through which the lymph collected from the medullary sinus exits at the hilum
Where are superficial lymph nodes? examples?
Where are the deep lymph nodes?
within the subcutaneous tissue: cervical axillary, inguinal
deep: beneath fascia, muscle, organs
What are the functions of lymph nodes? (3)
- filtration of lymph fluid
- maturation of lymphocytes
- phagocytosis of bacteria and cellular debris
What do you look for when evaluating lymph nodes?
- size and shape
- consistency, tenderness, mobility
- color, warmth
Where is Virchow’s node?
left supra-clavicular (intra-thoracic/abd CA)
What do epitrochlear nodes indicate?
secondary syphilis
What does the thoracic duct drain?
Master lymph vessels and drains:
- Left head/neck
- LUE
- L thorax/abdomen
- below the umbilicus
- receives from lumbar lymphatics