lymphoid system 1 Flashcards
innate immunity is
- immediate
- nonspecific actions
- first course of action
- include physical barriers
- include NKCs
- granulocytes
- leukocytes
- produced in bone marrow
physical barriers of innate immunity
- skin
- mucous membranes of GI tract
- respiratory
- urogenital tracts
natural killer cells (NKC)
- destroy various unhealthy host cells
- include virus or bacteria and tumorigenic cells
adaptive immunity
- acquired gradually by exposure to microorganisms
- aimed at specific microbial invaders
- slower response
- more recently evolved
- B and T lymphocytes
- memory lymphocytes
- produced in bone marrow
B and T lymphocyte activation in adaptive immunity
- against specific invaders
- specific molecules from antigen presenting cells
antigen presenting cells (APCs) are derived from
- monocytes
the lymphatic system protects against potentially harmful effects of
- pathogens
- foreign substances
- infectious agents (bacteria and viruses)
- abnormal cells
- can target tumor cells
the major function of the lymphoid system:
to serve as a source of immunocompetent cells that can react with and neutralize antigens and to distinguish self from non-self
the lymphoid system is comprised of
- lymphoid tissues
- organs comprised of lymphocytes and other cells of mononuclear phagocyte system
lymphoid tissue is classified as
specialized reticular connective tissue
arrangement of components of lymphoid system
- diffuse subepithelial lymphocyte aggregates
- densely packed
densely packed arrangement occurs in:
- lymphoid nodules
- are part of MALT
mucose associated lymphoid tissues (MALT) includes:
- tonsils
- payer patches
- appendix
- GI, respiratory, urinary, and reproductive tracts
lymphoid organs can be
- unencapsulated
- encapsulated
encapsulated organs include
- lymph nodes
- thymus
- spleen
unencapsulated organs include
- bone marrow
lymphoid organs can be classified as:
- primary
- secondary
primary lymphoid organs are
major sites of lymphocyte production and maturation
primary lymphoid organs include
- bone marrow
- thymus
what do B cell lymphocytes do?
- mediate humoral immunity by giving rise to plasma cells (synthesize antibodies)
- inactivate foreign antigens
what do T cell lymphocytes do?
- mediate cellular immunity against microorganisms
what do secondary lymphoid organs do?
- carry out immune response
secondary lymphoid organs include:
- lymph nodes
- spleen
- MALT
lymphoid tissues derive from:
mesoderm
- except thymus which derives from mesoderm and endoderm
MALT subdivided into
- GALT (gut)
- BALT (bronchus)
- NALT (nasal)
- VALT (vulvovaginal)
GALT includes
- tonsils
- Payer patches
- appendix
MALT contains
- B cells and T cells
- primarily B cells
- T cells predominate nearby areas
lymph nodes
- bean/kidney shaped
- found in lymphatic vessels and lymph
- occur as chains or groups
- in neck, groin, mesenteries, axillae, abdomen
lymph nodes derive from
the mesenchyme
main function of lymph nodes:
- filtration of lymph before it returns to thoracic duct
- production of lymphocytes that are added to lymph
- synthesis of antibodies (IgG)
- recirculation of lymphocytes
structure of lymph nodes:
- paracortex
- cortex
- medulla
lymph node flow
- afferent lymph vessels
- subcapillary sinus
- trabeculae sinus
- paracortex
- medullary sinus (medullary cord
- efferent vessel
where do lymphocytes enter high endothelial venules?
paracortex
high endothelial venules (HEVs) are where…
lymphocytes exit blood and become localized in lymph nodes
B cells localize where in the lymph nodes?
cortex
where do T cells localize in the lymph nodes?
paracortex
where do lymphocytes proliferate?
in germinal center of the spleen
- B lymphocytes remain in the germinal center
thymus function
Facilitates the foreign antigen-independent maturation of T lymphocytes
- much larger in children
thymus gland
- flat
- bilobed
- in anterior mediastinum
- involuted and parenchyma replaced by adipose connective tissue during puberty***
parenchyma of thymus is later…
replaced by adipose in adults
where does positive selection occur?
in thymus
medulla of thymus contains what?
hassel’s corpuscles
hassel’s corpuscles
- highly active
- produce hormones to help lymphocytes differentiate when located on periphery of thymus
the spleen produces:
- lymphocytes and antibodies
- these are delivered directly to the blood not the lymph
function of the spleen
- filtration of the blood (only lymphoid organ that does)
- defense against blood-born antigens
- main site of erythrocyte destruction
- produces antibodies and activated lymphocytes
splenic pulp components
- white pulp (lymphoid nodules and periarteriolar lymphoid sheaths - PALS)
- red pulp (sinusoids and splenic cords)
PALS is primarily made of
T cells
the spleen contains:
- lymphoid nodules
- periarteriolar lymphoid sheaths (PALS)
are lymphoid nodules in the spleen part of the MALT?
NO
comparison of major lymphoid organs
lymphatic drainage in teeth
- lymphatic vessels have been identified in vascular endothelial growth factor (VEGF) receptor 3
- located in root pulp
macrophages
- located in connective tissue, lymphoid organs, lungs, bone marrow, pleural, and peritoneal cavities
- produces cytokines and inflammation factors, is antigen processing and presenting
kupffer cells
macrophages of the liver
microglial cells
macrophages of CNS
Langerhans cells
antigen processing and presentation in epidermis
dendritic cells
antigen processing and presentation in lymph nodes and spleen
