The Lymphoid system Flashcards
Where do T cells go to mature?
thymus
Where do B cells go to mature?
bone marrow
What are the primary lymphoid tissues?
bone marrow and thymus
What are the secondary lymphoid tissues?
lymph nodes; spleen; waldeyers ring; epithelio-lymphoid tissues
What are the functions of the lymphoid system?
filtration of circulatory fluids and location for cells of the immune system; return lymph to the circulation
Where do afferent channels to the lymph nodes drain
?
lymph through the capsule into the peripheral sinus
How do arteries and veins serving the lymph node enter and exit the node?
hilum
How is lymph filtered in the lymph nodes?
filtered thorugh the node parenchyma
What cell populations are found in lymph nodes?
B cells; T cells; macrophages; APCs; dendritic cells; endothelial cells
Where are plasma cells found in lymph nodes?
medulla
What part of the lymph node are B cells associated with?
follicles and germinal centres
Which cell type is CD20 a marker for?
B cell
Which cell type is CD3 a marker for?
T cell
What tends to stimulate a predominant B cell resposne in a lymph node?
auto-immune conditions; infection
What tends to stimulate a predominate phagocytic resposne?
tumours
What tends to cause a predominant T cell resposne in lymph nodes?
viral infections; drugs eg phenytoin
What two veins form the portal vein?
splenic vein and SMV
What makes up the parenchyma of the spleen?
red pulp and white pulp
What is found in the red pulp?
sinusoids and cords
What supports the sinusoids in the spleen?
hopps of reticulin
What is found in the cords of the red pulp?
macrophages; fibroblasts; cells in transit
What is the function of the spleen?
detect; retina and eliminate unwanted foreign or damaged material; facilitate immune responses to blood borne antigens
What type of cell are found in the white pulp?
mainly T lymphocytes (CD4)
What is the white pulp?
per-arteriolar lymphoid sheath
What is the triad of hypersplenism?
splenomegaly; fall in one or more cellular components of blood; correction of cytopenias by splenectomy
What are the causes of hyposplenism?
iatrogenic; coeliac disease; sickle cell; sarcoid
What are the main features of hyposplenism the result of?
reduced red pulp function
What may be seen on blood film with hyposplenism?
Howell-Jolly bodies
