Intro to the Lymphatic System Flashcards
Why are lymphatic capillaries more permeable than the walls of blood capillaries
to allow large molecules to enter more readily
What are the primary lymphoid organs
bone marrow and thymus
Where does T cell maturation occur?
thymus
What is the Hassall’s corpuscle made of
aggregates of degenerating thymic reticular cells
- will see it more in an older section
What is Hassall’s corpuscle used for
accumulates more dead things, more mature people have more corpuscles
What is the blood-thymus barrier made of
- capillary endothelium
- thick basement membrane
- perivascular CT space (macrophages)
- layer of type 1 reticular cells
What is the role of the blood-thymus barrier
a continuous endothelium that prevents blood borne antigens from reaching the cortex
What is the role of the lymph node?
filter lymphatic fluid
- sites of Ag presentation and cell traffic
- reactive barrier against infection and tumor spreading
What is the lymph node made of
fibrous capsule with trabeculae
hilium
part of organs where you have arterial blood flow
Flow of lymph
- afferent lymphatics: carry lymph to nodes
- subcapsular sinus
- peritrabecular sinus (around the trabeculae)
- medullary sinus
- efferent lymphatics: carry lymph from nodes
HEV (high endothelial venules)
- important side of lymphocyte entry into the lymph node and the site at which blood-born lymphocytes can re-enter
- blood can come back into the lymph node via the HEV
- back up to the cortical area
- leave through the medulla
tonsils
lymphoid tissue on either side of the throat
- infection = tonsilitis
palatine tonsils
*palate/lingual = mouth/GI
- non-keratinized stratified squamous
- incompletely encapsulated
- have crypts for increased surface area
Why are the tonsils not completely encapsulated
not free floating, they’re linked to the body wall
- don’t need complete capsule
