Lymphatic Drainage Flashcards
Describe the structure of a lymph node
Fibrous capsule with trabeculae extending to the centre.
3 compartments:
1. Lymphatic sinuses
2. Blood vessels
3. Parenchyma (cortex, paracortex, medulla)
What are the two main functions of lymph nodes?
Phagocytic cells filter particulate matter and micro-organisms
Antigen presenting
What happens to B cells in lymph nodes?
Unstimulated B cells pass out rapidly to return to circulation
Activated B cells proliferate and remain in the node
How do B cells enter the lymph node?
Via post capillary High Endothelial Venules and pass to follicles.
What are follicle centre cells?
Activated B cells within lymphoid follicles.
Have either cleaved nuclei (centrocytes) or open or several nuclei (centroblasts)
What happens to the stimulated B cells in the lymph follicle?
Proliferate and undergo somatic hypermutation
Selected for by high affinity antibodies to the antigen presented by follicular dendritic cells
Take up the antigen, process and present it to T cells
T cells promote development of B cells by releasing IL 4
B cells become centrocytes then centroblasts
Centroblasts leave the follicle and pass to paracortex and medullary sinuses, where they become immunoblasts
What do immunoblasts give rise to?
Plasma cells or memory B cells
What is found in the Paracortex?
T Lymphocytes
Accessory and supporting cells
What is found in the medulla?
Macrophages
Large blood vessels
Medullary cords- lots of plasma cells. Antibodies pass out via the efferent lymphatic
Medullary sinuses
How are lymph nodes of the head organised?
Regional and terminal groups
What is the jugulo-digastric node?
Tonsillar node
Below and behind the angle of the mandible
Drainage of tonsil and tongue
What is the jugulo-omohyoid node?
Tongue node
Drains tongue, oral cavity, trachea, oesophagus, thyroid gland
What do the efferent lymph vessels from the deep nodes join to form?
Jugular lymph trunks
How do the jugular lymph trunks terminate?
Left: joins the thoracic duct, enters the left brachiocephalic vein at the junction between the subclavian and internal jugular veins.
Right: joins the right lymphatic duct, enters venous system at junction between subclavian and internal jugular veins
Describe the thoracic duct
Main duct for return of lymph to venous blood
Begins in abdomen at cisterna Chyli (L2)
Extends vertically in chest, curves posteriorly to left common carotid artery and left internal jugular vein
Empties into left brachiocephalic vein at left venous angle
