DAT bio chapter 11.3 human immune system Flashcards
The _____ are the first layer of innate immunity
outer walls
Outer wall of the first layer of innate immunity consists of what
Skin
cilia
stomach acid
symbiotic bacteria
Skin consists of
thick epidermis, dermis, and hypodermis. Also mucous membrane to trap pathogens and lysozyme to break down bacterial cell walls. Has sebaceous glands to secrete oil (sebum) as a barrier. Sebum also has antimicrobial properties.
cilia does what
- hair-like projections in the respiratory
tract that sweep away debris and pathogens.
stomach acid does what
gastric acid that kills microbes
due to low pH.
Symbiotic bacteria -
outcompete pathogenic
bacteria and fungi.
When the first layer of innate immunity are penetrated, the _____system will kick in
immune
5 signs of inflammation (DAT mnemonic
SLIPR Swelling Loss of function Increased heat Pain Redness
Swelling
permeable capillaries result in fluids
leaking into tissues.
Loss of function
- body part with
inflammation becomes less usable.
increased heat
increased blood flow results
in a higher temperature.
pain
throbbing pain caused by swelling,
which puts continuous pressure on nerve
endings.
redness
increased blood flow causes
redness of skin.
Diapedesis
process by which cells move
from the capillaries to the tissues in order to fight
pathogens.
Chemotaxis
method by which cells move
in response to a chemical signal. Immune cells
use chemotaxis to move to the tissues.
Five main types of leukocytes from highest to
lowest in quantity → Never Let Monkeys Eat
Bananas
Never Let Monkeys Eat Bananas - neutrophil -lymphocytes -macrophages -eosinophils -basophils
Neutrophils
phagocytes in innate immunity
that make up over half of all leukocytes.
lymphocytes
- B cells, T cells, and natural
killer cells. B and T cells are part of adaptive
immunity and must be activated. Natural
killer (NK) cells are part of innate immunity
and attack virally-infected cells + cancerous
cells. NK cells use perforin (create holes) and
granzyme (stimulate apoptosis) to lyse cells.
macrophages/monocytes
- phagocytes in innate immunity. Monocytes are the immature form found in blood vessels and macrophages are the mature form after diapedesis. Can also act as antigen-presenting cells to activate adaptive immunity.
eosinphils
part of innate immunity and
have granules that can be released to kill
pathogens, especially parasites.
basophils
least numerous leukocyte;
contains granules with histamine
(vasodilation) and heparin (an anticoagulant
to prevent blood clotting). Very similar to
mast cells, except basophils circulate as
mature cells while mast cells circulate as
immature cells.
Dendritic cells are part of ____ immunity and scan tissues using _____ and ____
innate
pinocytosis
phagocytosis
dendritic cells also act as
antigen-presenting cells like macrophages,
migrating to the lymph nodes to activate
adaptive immunity.
interferons are secreted by what and bind to what
virally infected cells,
bind to non infected cells to prepare them for a virus attack. also help activate dendritic cells
complement system: complement system) is a group of
approximately_____-
approximately 30 proteins that aid immune cells
in fighting pathogens. These proteins turn each
other on through the complement cascade,
which amplifies the complements effects by
releasing cytokines.
Complement protein actions:
Tags antigens for phagocytosis in a process
called opsonization
● Amplifies inflammatory response Eg. binds to
mast cells for increased histamine release
● Forms a membrane attack complex (MAC),
which pokes holes in pathogens and lyses
them
adaptive immune system is a what
specific immune response (targets specific antigens).
What is an antigen
an immunogenic foreign molecule
and is the target of the immune response.
What is the epitope?
important part of the antigen that
is recognized by the immune cell.
How does immune system recognize self proteins from non self proteins?
They use major histocompatibility complex (MHC), which is found on the surface of cells
foreign
antigens and foreign MHC will be identified as
enemies by the ______
immune system
what is the surface molecule present on all
nucleated cells, and each genetically different
individual will have a different MHC I molecule.
MHC class 1
Organ transplants that have different ___I may
lead to failure and rejection, so
immunosuppressants are given to transplant
patients.
MHC I
When does autoimmune diseases occur
when
the immune system attacks self MHC I.
_____surface molecule present on
antigen-presenting cells (dendritic cells,
macrophages) _______
MHC Class II
is used to present foreign
antigens to activate immune cells.
b cells control
antibody-mediated immunity
(humoral immunity) by managing the
production and release of antibodies. They can
also act as antigen-presenting cells.
B cell receptors (BCRs) are located on
B cells
and bind to antigen epitopes either free-floating
or on APCs. Each B cell has a unique BCR.
The clonal selection model describes the
development of _____
one type of BCR for every B cell.
Through clonal expansion, what happens
these B cells divide
into either plasma cells (antibody-secreting cells)
or memory B cells (to be activated later in case
of another attack).
Antibodies (immunoglobulins)
structurally identical to BCR but freely circulate in blood and lymph
Function of antibodies
tag antigens for phagocytosis,
neutralize the antigen by coating it, or activate the
complement system.
Structure of antibodies
Antibodies contain light
chains and heavy chains linked by disulphide
bonds. In addition, the variable region
recognizes different antigens while the constant
region is the same for antibodies within the
same class.
DAT Mnemonic:
Classes of Antibodies → Me And Eve Don’t Go
IgM igA igE igD igG
IgM
present in a pentameric form and is the
largest antibody. The first antibody to be
produced; activates the complement system.
IgA
- present in a dimeric form and found
most abundantly in bodily secretions.
Newborns receive passive immunity
through breast milk containing IgA. Also, IgA
mainly binds pathogens externally, outside
of circulation.
igE
monomer that is present on basophils
and mast cells as antigen receptors. When
bound to an allergen, triggers histamine
release and an allergic reaction.
igD
monomer that we have very little
information about. Only small amounts are
produced.
igG
monomer that is the most abundant
antibody in circulation. Also the only
antibody that can cross the placenta to give
fetus passive immunity. Helps the
complement system to cause opsonization
(tags antigens and subsequent phagocytosis).
Memory B cells do what
survive for a long time and lay
dormant until reactivated by the same antigen
that triggered the original clonal expansion.
Memory B cells are key to ____
vaccinations because
vaccines cause memory B cell production for
later reactivation. After reactivation, memory B
cells cause massive antibody production.
T cells control what
cell-mediated immunity by
directly acting on cells instead of sending
antibodies out.
T cell receptors (TCRs) are what
are unique just like BCRs,
binding only to one type of antigen per T cell.
Thus, T cells also undergo clonal selection just
like B cells.
T cells must bind to antigens presented on what to be activated
presented on APCs
(antigen-presenting cells) to be activated.
There are two ways antigens may be presented
to T cells:
MHC I Presentation:
MHC II Presentation:
MHC I Presentation:
T cells differentiate into
CD8 T cells (cytotoxic T cells), which directly
kill infected cells through perforin (poke holes)
and granzymes (cause apoptosis). However, T
cells are different from natural killer cells
because they are more specific and require
antigen presentation.
MHC II Presentation:
T cells differentiate into
CD4 T cells (helper T cells), which release
cytokines to boost both innate immunity and
adaptive immunity. These cytokines help attract
innate immune cells and increase proliferation
of other T and B cells.
Passive immunity refers to what
immunity one
organism gains from receiving the antibodies
from another organism that already has that
immunity.
ex of passive immunity
fetus gains passive
immunity through the placenta (IgG) while a
newborn gains passive immunity through breast
milk (IgA).
When fetus do not have their own active immunity what is it called?
immuno-naive
Active immunity refers to
immunity an
organism gains from being infected once already
by a pathogen. A vaccination introduces the
antigen or pathogen in a deactivated state to
stimulate active immunity, which is referred to as
artificial immunity in this case and induces
memory B and T cell formation.
