Immune system and cell mediated immune response
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73 Terms
types of immune responses
cellular, cell mediated, humoral, inflammatory
key features of the immune system
specificity, diversity, memory, self-limitation, self/non-self recognition
what does specificity mean in the immune system
T and B lymphocyte programmed to recognize a specific antigen and attack using the exact cell needed
what does diversity mean in the immune system
allowing activity against many different antigens
what does memory mean in the immune system
after first exposure, the immune system produces memory lymphocytes that allow a faster and stronger response to the same antigen
what does self-limitation mean in the immune system
the immune system is self-regulating and can turn off once the threat is gone, preventing unnecessary damage to healthy tissue
what does self/non-self recognition mean in the immune system
the ability to avoid attacking the body’s own cell but can target foreign cells
what is the definition of an antigen
any foreign substance with an immune response, the non-self
examples of antigens
bacteria, viruses, fungi, pollen, insect venom, transplanted organs, cancer cells
organs of the immune system
adenoids, tonsils, thymus, spleen, lymph nodes, lymphatic vessels, appendix, bone marrow, peyer’s patches
what happens in the bone marrow related to lymphocyte
it produces stem cells, immature B and T lymphocytes
where do B lymphocytes mature
bone marrow
what is the role of B lymphocytes once matured
produce antibodies as part of the humoral immune response
where do T lymphocytes mature
thymus
what is added to T lymphocytes during maturation in the thymus
T cell receptor which allows them to recognize antigens and become activated
do T lymphocytes mature in the bone marrow
no
when is the thymus most active
during childhood
where is the thymus located
in the neck region above the heart
when is the thymus fully developed
birth
what happens to the thymus as we age
gradually replaced by adipose tissue
what is TCR
T cell receptor
do all mature cells have a TCR
yes
what is the role of the TCR
it is the site that binds to individual antigens, making t cells antigen-specific
why is the TCR vital for immune system function
it allows T lymphocytes to be antigen specific and to distinguish self from non-self
which T lymphocyte with TCR is one of the most important cells of the immune system
helper T cells
why is HIV so damaging to the immune system
it attacks helper T lymphocytes and inhibits their ability to coordinate immune responses
what is the role of peripheral lymphoid tissue
the site where immune cells interact with specific antigens
what do peripheral lymphoid tissues do with antigens
they trap and process antigens to help produce an immune response
examples of peripheral lymphoid tissue
lymph nodes, spleen, respiratory tract, urogential tract, tonsils
how do lymph nodes trap antigens
antigens that enter the lymph fluid move into nodes where they are trapped and interact with immune cells
what is the spleen’s role in the immune system
an organ concentrated with T and B lymphocytes, filters antigens from circulation, site of interaction between immune cells and antigen
what cells are involved in the cellular immune response
macrophages, natural killer (NK) cells, antigen-specific cytotoxic T lymphocytes, cytokines
what does the cellular immune response target
our bodies cells that have been invaded by antigens
does the cellular immune response act on circulating/free antigens
no it specifically targets infected cells
what type of infections is the cellular immune response especially important for
viral infections since they hide inside bodies cells
what does the cell-mediated immune response destroy
virus-infected cells, cancerous cells, intracellular bacteria
what signaling molecules are stimulated during the cell-mediated immune response
cytokines
how does the cell-mediated immune response enhance the immune system
by boosting the activation of macrophages and natural killer cells
what is the first step of the cell-mediated response to a viral infection
an antigen-presenting cell (APC) ingests and phagocytizes the circulating antigen
after ingestion, what happens to the antigen inside the APC
the antigen is broken down into fragments
what do antigen fragments bind to inside the APC
bind to major histocompatibility complex (MHC) II molecules
what is the role of the MHC II molecule
holds the antigen fragment on the APC surface, displaying it for recognition by other immune cells
what does the APC look like after antigen presentation
a macrophage circulating with an antigen-MHC II complex displayed on its surface
what are the main types of antigen-presenting cells
macrophages, dendritic cells, B lymphocytes
what are macrophages and where do they come from
white blood cells that originate in the bone marrow and act as scavenger cells
where are macrophages found
in circulation and throughout various tissues
what is the primary function of macrophages as APCs
to ingest antigens, break them into fragments, bind them to MHC II, present them to helper T cells
how do macrophages help before the humoral response kicks in
help contain the infection
what makes dendritic cells effective APCs
rich in MHC II molecules and their primary role is antigen presentation
what are MHC molecules
recognition molecules that display antigens, divided into class I and II
where is MHC I found
on the surface of almost every cell in the body
what is the role of MHC I
they bind to antigens from inside infected cells and present them on the cell surface
which T cells interact with MHC I/antigen complexes
cytotoxic T cells via TCR
where is MHC II found
on APC; macrophages and dendritic cells
what do MHC II display
fragment of antigens that have been engulfed and processed inside APC
which T cells interact with MHC II/antigen complexes
helper T cells via TCR
what is the first step in the cell-mediated response
activation of helper T cells
how are helper T cells activated
by binding their TCR to the MHC II/antigen complex on an antigen presenting cell
can one macrophage activate more than one helper T cell
yes
what happens after helper T cell activation
they release cytokines which signals and activates other immune cells
what role do T helper cells play in the immune system
they activate and regulate the activity of other immune cells by releasing cytokines
what does the T helper cell activate and regulate
cytotoxic T cells, natural killer cells, B lymphocytes, macrophages, dendritic cells
what type of immune cell are natural killer cells
a type of lymphocyte
are natural killer cells specific to one antigen
no
what do natural killer cells kill
virus-infected and tumor cells
what is the role of natural killer cells before the cell-mediated response begins
help contain infection
what are cytokines
molecules that allow communication between immune cells and other tissues of the body
what do cytokines do to other immune cells
they enhance activation and regulate activation of other immune cells
which immune cells release cytokines during activation
helper T cells
how do cytokines regulate the immune response
they can turn the immune responses on or off
what activates T cytotoxic cells
MHC I complexes
what can T cytotoxic cells destroy once activated
virus-infected cells, bacteria or parasites, cancer cells, foreign cells
what is the main function of T cytotoxic cells in immunity
to directly kill abnormal or infected host cells
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Flashcards (167)