lymphoid tissues Flashcards
primary lymphoid tissues
bone marrow and thymus
generation of mature but antigen-naive T and B cells
development of antigen-recognition
secondary lymphoid tissues
spleen
lymph nodes
Peyer’s patches
tonsils
where naive lymphocytes wait to be activated
funnel antigen to antigen-specific B and T lymphocytes
tertiary lymphoid tissues
skin, GI tract, lungs, vagina
where elimination of antigen occurs
battlefield where immune system defends tissues from microbes
typically have direct contact with external environment
function of bone marrow and thymus
bone marrow: source of stem cells that can differentiate into all formed elements of peripheral blood
thymus: site of T lymphocyte maturation
structure and function of lymph nodes
a
structure and function of spleen
a
role of Peyer’s patches in immune response
secondary lymphoid tissue in the GI tract (MALT)
expose immune system to antigens across the mucosal epithelium
where are autoreactive T cells deleted
thymus
at what stage are autoreactive B cells deleted
immature B cell stage (in bone marrow)
which cells are known as thymic nurse cells
cortical epithelial cells
promote thymocyte differentiation by providing cell-to-cell contact, cytokines, and peptide hormones
what happens to the thymus after puberty
atrophies and is replaced by adipose tissue
how is T cell immunity maintained after atrophy of thymus
long-lived memory T cells and division of mature peripheral T cells
what are Hassall’s corpuscles
thymocyte graveyards
only 5% of thymocytes mature and leave thymus
when do thymocytes begin expressing TCR, CD3, CD4/8
after thymocytes migrate from the cortex to the medulla
become mature T lymphocytes when they reach the medulla
when mature T cells leave the thymus, where do they go
secondary lymphoid tissues
what are T cell precursors called when they leave the bone marrow and home to the thymus
prothymocytes
travel from bone marrow to thymus via peripheral blood
purpose of lymphatic channels
to drain lymph (extracellular fluid) from tissues of the back and return it back to the bloodstream
where are lymph nodes
interspersed along the course of lymphatic channels
serve to house immune system cells such as macrophages, B and T cells
prevalent in axillary, inguinal, and cervical regions
where does the thoracic duct empty into
left subclavian vein
within the thymus, thymocytes migrate from
cortex to medulla (toward center of thymus)
what are found in germinal centers
proliferating B cells
within the lymph node cortex, what are the three B cell rich areas
primary follicles = resting B cells
secondary follicles = antigen-activated B cells
germinal centers = proliferating B cells
what is the paracortex
T cell rich area that houses T helper cells
where are dendritic cells found in lymph nodes
throughout the T cell rich areas
