Immune System Detailed Exam 2025
Abo blood groups - -genetically determined classes of human blood; based on the
presence or absence of carbohydrates a and b on the surface of red blood cells. The
abo blood group phenotypes, also called blood types, are a, b, ab, and o.
Acquired immunity - -the kind of defense that is mediated by b lymphocytes (b cells) and
t lymphocytes (t cells). It exhibits specificity, memory, and self-nonself recognition. Also
called adaptive immunity.
Active immunity - -long-lasting immunity conferred by the action of a person's b cells
and t cells and the resulting b and t memory cells specific for a pathogn. Active
immunity can develop as a result of natural infection or immunization.
Aids (acquired immunodeficiency syndrome) - -the name of the late stages of hiv
infection, defined by a specified reduction of t cells and the appearance of characteristic
secondary infections.
Anaphylactic shock - -an acute, whole-body, life-threatening, allergic response.
Antibody - -a protein secreted by plasma cells (differentiated b cells) that binds to a
particular antigen and marks it for elimination; also called immunoglobulin. All antibody
molecules have the same y-shaped structure and in their monomer form consist of two
identical heavy chains and two identical light chains joined by disulfide bridges.
Antigen - -a macromolecule that elicits an immune response by lymphocytes.
Antigen presentation - -the process by which an mhc molecule binds to a fragment of an
intracellular protein antigen and carries it to the cell surface, where it is displayed and
can be recognized by a t cell.
Antigen receptor - -the general term for a surface protein, located on b cells and t cells,
that binds to antigens, initiating acquired immune responses. The antigen receptors on
b cells are called b cell receptors (or membrane immunoglobulins), and the antigen
receptors on t cells are called t cell receptors.
Antigen-presenting cell - -a cell that ingests bacteria and viruses and destroys them,
generating peptide fragments that are bound by class ii mhc molecules and
subsequently displayed on the cell surface to helper t cells. Macrophages, dendritic
cells, and b cells are the primary antigen-presenting cells.
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Apoptosis - -the changes that occur within a cell as it undergoes programmed cell
death, which is brought about by signals that trigger the activation of a cascade of
suicide proteins in the cell destined to die.
Autoimmune disease - -an immunological disorder in which the immune system turns
against self.
B cell receptor - -the antigen receptor on b cells: a y-shaped, membrane-bound
molecule consisting of two identical heavy chains and two identical light chains linked by
disulfide bridges and containing two antigen-binding sites; also called a membrane
immunoglobulin or membrane antibody.
B lymphocyte (b cell) - -a type of lymphocyte that develops to maturity in the bone
marrow. After encountering antigen, b cells differentiate into antibody-secreting plasma
cells, the effector cells of humoral immunity.
Cd4 - -a surface protein, present on most helper t cells, that binds to class ii mhc
molecules on antigen-presenting cells, enhancing the interaction between the t cell and
the antigen-presenting cell.
Cd8 - -a surface protein, present on most cytotoxic cells, that binds to class i mhc
molecules on target cells, enhancing the interaction between the t cell and the target
cell.
Cell-mediated immune response - -the branch of acquired immunity that involves the
activation of cytotoxic t cells, which defend against infected cells, cancer cells, and
transplanted cells.
Class i mhc molecules - -a collection of cell surface proteins encoded by a family of
genes called the major histocompatibility complex. Class i mhc molecules are found on
nearly all nucleated cells.
Class ii mhc molecules - -a collection of cell surface proteins encoded by a family of
genes called the major histocompatibility complex. Class ii mhc molecules are restricted
to a few specialized cell cell types, commonly called antigen-presenting cells (dendritic
cells, macrophages, and b cells).
Clonal selection - -the process by which an antigen selectively binds to and activates
only those lymphocytes bearing receptors specific for the antigen. The selected
lymphocytes proliferate and differentiate into a clone of effector cells and a clone of
memory cells specific for the stimulating antigen. Clonal selection accounts for the
specificity and memory of acquired immune responses.
Complement system - -a group of proteins that complement the antibodies and
phagocytic cells; assists in ridding an organism of microbes and damaged cells;
promotes inflammation.
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