Secondary lymphoid tissues Flashcards
What are the secondary lymphoid tissues?
Lymph vessels, lymph nodes, spleen and MALT
What does MALT stand for?
mucosa associated lymphoid tissue
What are the secondary lymphoid tissues in terms of lymphocytes?
The site where mature lymphocytes are exposed to and stimulated by antigen
Another name for secondary lymphoid tissue
Peripheral lymphoid organs
Is migration of lymphocytes from primary to secondary random or highly specific?
Highly specific
What do lymphocytes enter secondary tissues via?
HEVs
What is diapedesis?
Squeezing of lymphocytes through endothelium into nodes
do lymph vessels have valves?
Yes, ensure unidirectional flow without a pump
function of lymph vessels
drain tissue fluid from connective tissues. drain to lymph nodes
Where are lymph nodes saturated?
Groin and neck
Describe lymph nodes
Highly organised, bean shaped junctions between lymph vessels
function of lymph nodes
To filter lymph
Describe flow in lymph nodes
enter via afferent lymphatics to cortex, pass through paracortex, exits via efferent lymphatics in medulla.
Where do HEVs enter the lymph nodes?
Paracortex
Where are B cells found in the lymph nodes?
primary and secondary follicles in the cortex
Where are T cells found in the lymph nodes?
Paracortex
How big is the spleen?
fist sized
location of the spleen
Associated posteriorly with the 9-11th ribs but separated from them by the diaphragm superiorly.
Relationship between spleen and pancreas
The tail of the pancreas points to the spleen
Relationship between the spleen and large intestine
It rests on the left colic flexure of the large intestine
function of spleen
collects antigen from blood and presents to lymphocytes, filters blood and removes and disposes of ageing red blood cells and immune complexes.
What are the two internal structures of the spleen?
Red pulp and white pulp
What is red pulp?
well perfused tissue of the spleen for filtration
What is white pulp?
similar to lymph nodes, packed with B and T cells and dendritic cells
Where are T cells located in white pulp?
in periarteriolar lymphoid sheaths- PALS
Where are B cells located in white pulp?
beyond sheath in a corona around the germinal centres.
