Immune System Flashcards
What are microbes?
bacteria, fungi, viruses, parasites
What are non-microbials?
pollen, insect venom, transplanted organs
What are inert substances?
dirt and wood
What are antigens?
- substances foreign to the host which can stimulate an immune response
- examples include bacteria, pollen, etc.
- also know as immunogens
What is an epitope?
the discrete immunologically active sites on antigens
• the portion of the antigen that interacts with the antibody
• a single antigen may have multiple antigenic determinants, each of
which is capable of activating a distinct clone of T and B cells
What are Major Histocompatibility Complex (MHC) molecules?
self recognition molecules (glycoproteins) located on the surface of all
nucleated cells
- unique for each person
Where are Class I MHC molecules found?
on all nucleated cells
Where are Class II MHC molecules found?
only on macrophages and B lymphocytes
What are cytokines?
• small proteins produced during an immune response which regulate the movement, proliferation,
and differentiation of leukocytes and other cells
• chemical messengers
What are cytokines (chemical messengers) made by?
made by helper T cells, macrophages, and other cells such as fibroblasts
Examples of cytokines
interleukins
• interferons (α, β, γ)
• tumor necrosis factor (TNF)
• colony stimulating factors
Which cell types involved in the immune response are found and activated in the lymph nodes?
macrophages • B lymphocytes • T lymphocytes - helper T cells (CD4+) - cytotoxic T cells (CD8+) • natural killer (NK) cell
Name the two different kinds of T lymphocytes
helper T cells (CD4+)
cytoxic T cells (CD8+)
What is the first line of defense in the NON specific immune response?
skin and mucous membranes
What is the second line of defense in the NON specific immune response?
relatively rapid response, occurs within minutes to hours, to prevent establishment of infection
What is the second line of defense initiated by?
tissue injury
What are the steps involved in the second line?
vasodilation
• enhances delivery of neutrophils and monocytes
- capillary leakiness
• plasma and cells able to move into interstitial spaces
- chemotaxis
• WBCs attracted to injured tissue
- phagocytosis
• relies on recognition of foreign vs. self
How do opsonins play a role in phagocytosis?
opsonins are antibodies or other substances that become bound to bacteria or foreign cells
and enhance phagocytic activity
What acts as an opsonin by enhancing phagocytic activity?
antibodies or complement proteins typically play this role
What is a complement?
a group of proteins present at all
times in the blood, in an inactive form
What are the 3 things that happen when complement is activated?
- a group of 5 of the complement proteins forms a
complex called the membrane attack complex
(MAC) which is able to insert itself in the
membrane of bacteria and create a pore or
channel that ultimately causes cell lysis and
death
2.activation of complement enhances most of the events of the normal inflammatory response - activated complement can act as an opsonizing agent, enhancing phagocytosis of
opsonized cells
What is the membrane attack complex (MAC) related to?
another protein secreted by cytotoxic T cells called perforin
most of the events of the inflammatory response are enhanced by?
the activation of complements
What inhibits viral replication non-specifically?
release of IFN-α and IFN-β by leukocytes and fibroblasts respectively
what carries out the other non-specific mechanism?
NK cells that also kill non-specifically
What does the specific immune response defense mechanism require?
requires specific recognition of an antigen which is typically mounted against bacteria, extra-cellular viruses, and non-microbials
also called adaptive immunity and is a slower response
What are the two forms of specific immune response?
- cell-mediated
- antibody mediated (humoral immune response)
What does antibody mediated immune response target?
it goes against bacteria and extra-cellular viruses
What does cell-mediated immune response target?
against intracellular viruses and cancer cells, which are ‘self cells
gone bad’, changed in some way, no longer recognized as normal ‘self’