Lymphoid Organs Flashcards
Provides defense or immunity against infectious agents ranging from viruses to multicellular parasites
immune system
Preesixting nonspecific defense that involves immediate and nonspecific actions
innate immunity
Natural killer cells that destroy various unhealthy host cells including those infected with virus or bacteria as well as certain potentially tumorigenic cells
Phagocytes
Specific type of immunity that is acquired gradually by exposure to microorganisms; slower to respond
adaptive immunity
These are derived from monocytes that become activated against specific invaders by being presented with specific molecules from those cells by APCs
B & T lymphocytes
aimed at specific microbial invaders and involve production of memory lymphocytes
adaptive immune responses
A response that involves antibody production
humoral
A response that involves cytotoxic elimination via CDB
Cellular
A molecule recognized by cells of the adaptive immune system and typically elicits a response from these cells
antigen
A glycoprotein of the immunoglobalin family that interacts with an antigenic determinant that is secreted by plasma cells in response to antigen
antibodies
Assist immune responses by producing cytokines that promote differentiation of B cells into plasma cells
helper t cells
activate macrophages to become phagocytic, activate cytotoxic lymphocytes, and induce many parts of an inlammatory reaction
helper t cells
represents cellmediated immunity
cytotoxic t lymphocytes
allowing immune tolerance, maintaining unresponsiveness to self-antigens and suppressing excessive immune responses
regulatory cells
acts to supplement the central tolerance that develops in the thymus
peripheral tolerance
Group of cells, tissues, and organs that monitor body surfaces and internal fluid compartments and react to the presence of potentially harmful substances
lymphoid organs
primary or central lymphoid organ in which T cells are produced
thymus
Its main function is the induction of central tolerance, which along with regulatory T cells prevents autoimmunity
thymus
A potent source of cytokine which is necessary for the maturation and differentiation of T lymphocyte
Thymic or Hassall’s corpuscles
Provide a framework for the developing t cells
epithelioreticular cells
Epithelioretricular Cell:
functions as a barrier that isolates developing T cells from the connective tissue of the organ
type 1
Epithelioretricular Cell:
express MHC and MHC II molecules, which are involved in thymic cell education
Type II
Epithelioretricular Cell:
Functional barrier, possess MHC I and MHC II molecules
Type III
Epithelioretricular Cell:
They create the barrier at the corticomedullary junction
Type IV
Epithelioretricular Cell:
Provide the cellular framework of the medulla and to compartmentalize groups of lymphocytes
Type V
Epithelioretricular Cell:
form the most characteristic feature of the thymic medulla, the thymic (Hassall’s) corpuscles
Type VI
Protects developing lymphocytes in the thymus from exposure to antigens
Blood thymus barrier
Thymus has an ________ lymph vessel but no __________ lymph vessel so as to protect the developing lymphocytes from exposure to external antigens.
efferent and afferent respectively
Occurs in the cortex and allows survival only of T cells with functional TCRs recognizing MHC Class I and class II molecules
Positive selection