Organs of the Immune System: pgs 9-10 Flashcards
The lymphatic system is a _____ pressure system, so the lymphatics are very thin walled.
Low pressure
What pharyngeal pouches develop to make up the thymus?
3rd and 4th pharyngeal pouches
________ are rapidly dividing lymphocytes that populate the cortex of the thymus.
Thymocytes
T/F - T cells must mature under the influence of the thymic epithelium in order to cary out cell mediated immunity.
True
What is the term used when T cells mature in the thymic epithelium?
Education
Approximately how many thymocytes will die without leaving the thymus?
90%
The thymic cortex is extremely sensitive to _______________ and underconditions of stress, the thymus shrinks.
corticosteroids
Can antigens enter the thymus?
No. No antigens can enter the thymus because the blood vessels entering the thymus have unusually thick basement membranes and there is no lymphatic drainage
What are two hormones (of many) that are secreted by the thymus?
Thymosin and thymopoietin
What are the primary lymphoid organs?
Bone marrow and thymus
What do lymphocytes do in secondary lymphoid organs/tissues?
They function - they ARE NOT made and mature there (only in primary lymphoid organs)
What are some secondary lymphoid organs?
Spleen
Lymph Nodes
Peyer’s patches
Others
Where do the B cells reside in lymph nodes?
Follicles
Where do T cells, macrophages and dendritic cells reside in the lymph node?
Paracortex
What is the flow of lymph through the lymph node?
Subcapsular sinus -> B area -> T area
What cell is a descendant of a B cell?
Plasma cell
What do T helper cells do?
Up regulate and enhance response
T/F - both T and B cells circulate?
False - Just T cells circulate, B cells do not.
What do Ts cells do?
They shut down an ongoing immune response (energy expensive and damage to own tissues).
Where do lymph nodes cluster?
Where the appendages meet the trunk.
A “nude” mouse or rat has no ________. In humans its call DiGeorge Syndrome.
Thymus
What’s the difference in a neonatal thymectomy and an adult thymectomy?
Neonatal - animal dies of wasting away due to intestinal bacteria and other normal flora
Adult - No immediate consequences, animal seems normal at first, normal Ab due to mature T cells in periphery, animal will die at end though due to loss of T cells over time
