The Immune System I Flashcards
The body has three lines of defense against attack by foreign invaders: _____, _____ and
_____.
non-specific barriers; non-specific defenses; specific defenses
The skin is an example of a(n) _____. Physically, the outer layer is highly-cross-linked
keratin and is waterproof, blocking many invaders and their toxins.
non-specific barrier
Invaders not only have difficulty penetrating the skin’s structure, they are also repelled or
destroyed by the skin’s _____
acidic secretions
. Tears, saliva, and other secretions include lysozyme which _____.
breaks down bacterial walls
Mucous membranes and the cells that line them serve as a(n) _____: invaders become
trapped in the mucous and are swept out by _____.
non-specific barrier; ciliated
cells
Most microbes living in the food (or drink) which we ingest are destroyed by _____ before
they can cross into the body: this is a(n) _____.
gastric juices; non-specific
barrier
_____ are found on many bodily surfaces; they remove nutrients and other materials that
would otherwise be available to pathogenic species.
Symbiotic bacteria
The second line of defense in the immune system uses _____ to attack a(n) _____
invader.
chemical and cellular methods;
unrecognized
Lymphocytes which mature in the lymph system (as opposed to in the marrow or thymus)
are called _____, and are a part of the non-specific defense system.
natural killer (NK) cells
_____ recognize cells whose surface markers are drastically “non-self” - missing major
markers or containing non-human glycoproteins - and kill them. (They [are/are not?]
phagocytic.)
NK cells; are not
Neutrophils and macrophages ingest _____, and so play a role in non-specific defenses.
foreign material and debris
Macrophages sometimes kill their prey with chemicals including peroxide and bleach in a
process called _____.
the respiratory burst
A set of about 20 proteins present in the blood that, when activated, bind to pathogens
and both _____ and _____ are called “complement.”
attract phagocytes; disrupt the
pathogen’s membranes
In the “classical pathway” for complement activation, complement proteins recognize
_____.
antibodies bound to antigens
In the “alternative pathway” for complement activation, complement proteins recognize
_____.
polysaccharides on a
microorganism’s surface
“Viral infections” are infections in which viral _____ enter the cell, and the cell is forced to
make _____ instead of, or in addition to, its own.
nucleic acids; viral proteins
Many cells, after being infected by a virus, manage to secrete _____ which stimulate
neighboring cells to resist viral infection and ultimately signal the immune system.
interferons (IFNs)
_____ is a systemic response in which cellular metabolism is accelerated and which
creates a hostile environment to the invader: the danger is that, if excessive, it may also
damage host tissue.
Fever
The four signs of acute inflammation are _____, _____, _____, and _____.
redness; heat; swelling; pain
The inflammatory response is a(n) _____.
non-specific defense
The inflammatory response is initiated when _____ and nearby circulating cells.
chemicals are released by
injured cells
Vasodilation increases _____ and causes redness and heat.
blood flow
Increased _____ causes local edema; this in turn causes swelling and pain.
capillary permeability
Increased capillary permeability allows clotting factors to leak into the interstitial fluid: as a
result _____.
pathogens become trapped in
the resulting fibrin mesh
Phagocytes and lymphocytes are attracted to the signals released by damaged tissue in a
process called _____.
chemotaxis
_____ (white blood cell production) is increased in response to signals released by _____
during the inflammatory response.
Leukopoiesis; damaged tissue
_____ is produced by the liver. This protein has several functions in immunity; it is used
as a diagnostic tool, since its presence indicates that _____.
CRP (C-reactive protein);
inflammation is present
somewhere in the body
As leukocytes approach the injury, they begin to _____, rather than floating freely in the
blood. This process is called _____.
cling to the capillary walls and
‘walk’ along them; margination
If the body is able to recognize an invader, a third line of defense is available: the _____
of the immune system.
specific (or adaptive) branch
When leukocytes find the damaged region, they _____ into the interstitial area in a
process called _____.
squeeze through the
permeable capillaries;
diapedesis
Adaptive immunity requires five tasks: _____, _____, _____, _____ and _____.
recognition; lymphocyte
selection; lymphocyte
activation; destruction;
memorization
One task of the immune system is recognition of alien (_____) cells. To assist in this task,
self cells include proteins in their plasma membrane called _____ proteins which serve as
a highly recognizable uniform.
non-self; major
histocompatibility complex
(MHC)
The MHC proteins are also called the _____.
human leukocyte antigen (HLA)
Proteins for the MHC originate from 20 _____ with over 50 _____ each, so that no two
individuals will have the same MHC.
genes; alleles
During the construction of the MHC _____ are incorporated. Abnormal proteins in the
MHC are recognized by T-lymphocytes as “non-self.”
small pieces of proteins from
within the cell
There are two types of MHC: MHCI is displayed by _____, but MHCII is presented by
_____. The latter carries the news of the infection throughout the body or serves to signal
that help is needed in an infected region.
all body cells; cells within the
immune system only
Cells that present the MHCI are doing to so say, in essence, “Look what I _____.”
made
Antigen presenting cells are phagocytes that have _____ . They break
down antigens and _____.
ingested an invader;
incorporate pieces into MHCII
Cells that present the MHCII are doing to so say, in essence, “Look what I _____.”
ate
Cells that present the MHCII are called _____.
antigen presenting cells, or
APCs
In 2011, a Nobel prize was awarded for work describing one type of _____, the dendritic
cell.
APC OR antigen presenting cell
Dendritic cells are produced in the bone marrow and migrate to _____.
peripheral tissues and organs
Dendritic cells in peripheral tissue _____ but cannot yet activate T-cells, and so are said
to be immature.
phagocytose pathogens
Dendritic cells that have phagocytosed a pathogen migrate to _____, maturing on the way
lymph nodes
Once mature, dendritic cells are no longer phagocytic; instead, they specialize in _____,
and activating them.
presenting antigens to T-cells
_____ can be recognized by antibodies or lymphocyte receptors without modification.
Complete antigens
Antigens are often large, and may have many sites (called _____ or _____) to which
antibodies or lymphocyte receptors may bind.
antigenic determinants;
epitopes
Haptens are _____ that are too small to _____, but which may interact with proteins of the
body and then may be recognized as potentially harmful.
incomplete antigens; stimulate
the immune response
The cells responsible for distinguishing self from non-self cells are the _____.
lymphocytes
Each lymphocyte can recognize _____ antigens, and so the body’s ability
to recognize many different antigens depends on having _____.
one single; many different
lymphocytes
_____ involves recognition of an antigen by a specific lymphocyte, after which the
lymphocyte is ready for activation.
Lymphocyte selection
Lymphocytes remain inactive and do no proliferate until _____ and (usually) a co-stimulator is sensed.
an antigen is recognized
Activation of a lymphocyte refers to the cell’s commitment to proliferate. Since each
daughter cell recognizes the same antigen, the process is called _____.
clonal selection
Since each antigen may have several sites to which antibodies may bind, more than one
B-cell clone may produce antibodies to each antigen. A collection of such antibodies is
said to be _____.
polyclonal
If one single B-cell is cloned in the laboratory by selection against one single antigenic
determinant on an antigen, only one type of antibody is produced. Such antibodies are
said to be _____.
monoclonal
Most lymphocytes, in order to become activated after an antigen binds, must also bind to
a(n) _____. This serves as a “double-check” to prevent _____.
co-stimulator; accidental
activation
_____ or _____ act as co-stimulators
Chemicals released by nearby
cells; membrane proteins on
the non-self or abnormal cel
Killer T-cells, as part of the adaptive immune response, _____ and _____ the pathogen
directly. They are also called _____ cells, because of the type of receptor on their surface.
recognize; attack; CD8
Antibodies bound to a pathogen trigger attacks by _____.
the innate immune system
When activated lymphocytes proliferate, some of the daughter cells are always _____:
they must _____ if they are to become activated.
inactive; bind antigens
