Organs of the Haematopoietic System Flashcards
(52 cards)
T cells are involved in what in the immune system?
in direct cellular killing
B cells are involved in what in the immune system?
in producing antibodies
What does the body need to ‘vet’ T and B cells for?
to check that they don’t react and attack our own body’s proteins (antigens)
What do primary lymphoid tissues generate?
specific immune cell populations
Usually T or B cells rather than both
What do secondary lymphoid tissues generate?
specific immune responses
T and B cells activated and proliferate in response to foreign antigens
Expansion of T cells
B cells form antibodies
Typified by the presence of ‘germinal centres’ packed with B cells
Give examples of primary lymphoid organs?
thymus and bone marrow (Bursa of Fabricius in birds)
maturation of T and B lymphocytes
Give examples of secondary lymphoid organs?
spleen, lymph nodes, MALT/GALT, tonsils & adenoids
initiation of immune response
give examples of tertiary lymphoid organs:
ectopic lymphoid tissues that develop at sites of chronic inflammation in non-lymphoid organs
lobes of the thymus?
lobes divided into lobules by trabeculae (or connective tissue walls)
What is the thymus?
an organ that provides environment for T cell development - ‘education’
what does each lobe of the thymus have?
an outer CORTEX and inner MEDULLA
How many steps are thymocytes educated in?
2 step process by resident cells
What happens to thymocytes that are not selected to be educated?
they undergo apoptosis and are phagocytosed by macrophages
What is the major role of the spleen?
the spleen is a secondary lymphoid organ whose major role is to survey the presence of foreign antigens in blood
what does the spleen consist of?
of a capsule with fibrous partitions (TRABECULAE)
What are the two types of tissue that make up the spleen?
red and white pulp
What is red pulp?
it filters and removes damaged or aged red blood cells - phagocytosis by macrophages
extracellular fluid drains into where?
into vessels called LYMPHATICS
where are lymph nodes located?
within the lymphatic system to allow the surveillance of antigen and the initiation of adaptive immune response
where may foreign antigen/pathogens present in tissue drain to and by what?
drain into lymphatics by antigen presenting cells
structure of lymph nodes?
they are small, bean-shaped, tissue aggregates at junctions of major lymph vessels - 1-25mm diameter becoming much larger during infection
what are lymph nodes surrounded by?
by a capsule & consisting of 3 main areas: cortex, paracortex & medulla
what enters via the AFFERENT lymphatic?
Lymph carrying antigen and DCs enter via the afferent
where do lymphocytes enter blood via?
via HIGH ENDOTHELIAL VENULES (HEV)
