Immune System II Flashcards
_____ are immunocompetent (mature) lymphocytes created during an infection. They
remain alive long after the infection, allowing the body to “remember” the antigen and
react quickly if it returns.
Memory cells
Memory cells express _____ that was expressed by the parent lymphocyte.
the same antigen receptor
For the body to mount a specific defense against a newly encountered invader takes
_____ . (There may be only a single lymphocyte in the body that happens to
bind to it!)
days or weeks
The response to a newly encountered invader is called the _____.
primary immune response
Re-exposure, even years later, to an antigen that has been responded to before results in
a specific defense that takes _____ to mount. This is due to the presence of _____.
(There are thus many lymphocytes in the body that are able to bind to the antigen.)
only hours; memory cells
The response to an invader that has been attacked in the past is called the _____.
secondary immune response
Once a lymphocyte is capable of binding to a specific antigen, it is said to be _____ or
_____.
mature; immunocompetent
Immunocompetent lymphocytes have a set of _____ on their surface which can bind to a
specific antigen.
receptors
The antigen binding receptors of lymphocytes are produced by the _____ that produce
them, so that the number that can be made by a single person is very large.
shuffling of portions of the
genes
. Immature lymphocytes are formed from hematopoietic stem cells in the _____.
bone marrow
Each immature lymphocyte displays _____, but most such cells are unwanted.
a single antigen-binding
receptor
Lymphocytes whose antigen receptors do NOT react with ‘self’ cells are said to be _____,
but many immature lymphocytes do not meet this standard.
tolerant
Most B-cells whose receptors bind to “self” proteins are destroyed in _____.
the bone marrow
In the thymic cortex, immature T-cells that _____ are allowed to survive until the next
stage: those that can’t, die. (+ binding = live) This is called _____ selection.
recognize “self” MHC proteins;
positive
In the thymic medulla, immature T-cells whose antigenic receptor binds to _____ are killed
(- binding = live). This is called _____ selection.
“self” proteins displayed by the
MHC; negative
The acquired immune response can be divided into two branches: the _____ response
recognizes antigens or pathogens that are not associated with any “self” cells.
humoral
The acquired immune response can be divided into two branches: the _____ response
recognizes antigens that are associated with “self” cells (such as virally infected cells, or
antigen presenting cells).
cell-mediated
Humoral immunity is mediated by _____ produced by plasma cells present in the body’s
“humors” or fluids.
antibodies
B-cells recognize antigens that are _____: that is, that are not displayed as part of a MHC
free in the body
The first response in the humoral branch of the immune response is _____.
the binding of a B-cell to an
antigen
When a B-cell encounters an antigen and has been activated, it proliferates into two types
of cells: _____ and _____.
plasma cells; memory cells
Plasma cells produce antibodies that can bind to _____.
the same antigen that was
recognized by the parent B cell
Antibodies are produced by _____ in the lymph.
plasma cells
Antibodies are _____, each of which can bind to _____ identical antigens.
proteins; two or more