Lymphatics Flashcards
When does the lymphatic system begin to develop embryologically?
Week 5, significant presence by week 20
What components of the lymphatic system come from mesoderm?
Lymphatic vessels, lymph nodes, spleen, myeloid tissue
What components of the lymphatic system come from endoderm?
Thymus and parts of the tonsils
What role does the lymphatic system play in nutrition?
Chylomicrons are too big to cross into capillaries so they travel via lacteals to larger lymphatic vessels through the thoracic duct to the venous system
What tissues do not have lymphatic vessels?
Epidermis, endomysium of muscle, cartilage, bone marrow
What is the order of lymph flow from tissues?
Terminal lymphatics -> collecting vessels -> afferent lymph vessels -> lymph nodes -> efferent lymph vessels -> lymphatic trunks -> thoracic duct or right lymphatic duct -> venous system
What are the chains of muscular units called in lymphatic collecting vessels?
Lymphangions - two-leaflet bicuspid valves
What is the path of lymph flow through a lymph node?
Afferent lymphatics -> subcapsular space -> outer cortex -> deep cortex -> medullary sinus -> efferent lymphatics
What is the cisterna chyli?
Located at L1-L2, drains lymphatic trunks of the lower body and gives rise to the thoracic duct
Where does the thoracic duct originate and terminate?
Cisterna chyli at L1-L2
Goes through Sibson’s fascia and takes a u-turn to drain into L subclavian/IJ veins
What does the thoracic duct drain?
L head/neck, LUE, L thorax/abdomen, everything inferior to umbilicus
Where does the right lymphatic duct originate and terminate?
Junction of R jugular and subclavian trunks
Empties at R subclavian/IJ venous junction
What does the R lymphatic duct drain?
R head/neck, RUE, R thorax, heart, lungs
Where is the spleen located?
Beneath ribs 9, 10, 11 on the left against the diaphragm
What does the spleen do?
Rids body of damaged/deformed RBCs, synthesizes immunoglobulins, clears bacteria
Where is the liver located?
RUQ at costal margin near diaphragm
What is the liver’s lymphatic function?
Forms half of the body’s lymphatic fluid, clears bacteria, part of hepato-biliary-pancreatic venous and lymphatic drainage
Where is the thymus located?
Anterior mediastinum
What is the function of the thymus?
Maturation site for T-cells, doesn’t do much in adults
Where are the tonsils located?
Palatine - lateral pharynx
Lingual - posterior 1/3 of tongue
Pharyngeal - nasopharyngeal border
What do tonsils do?
Build immunity in early life, nonessential in adults
Where is the appendix located?
Proximal end of the large intestine
What does the appendix contain?
Lymphoid pulp
What is the function of the appendix?
Part of gut-associated lymphoid tissue (GALT)
