Transcript Advanced Biology

Advanced Biology
Chapter 22
Nonspecific Body Defenses
and Immunity
Nonspecific
Specific
– Innate
– Adaptive
Intact
skin and mucosa
Phagocytes
Other
cells
(inflammatory)
Specific
Defense
B Cells and T Cells
Functional
No
System
Organs
Trillions of Cells
Resistance
to Disease
Nonspecific
Specific
Keratin
provides a
barrier – resistant to
weak acids/bases and
bacterial toxins
Acidic
– pH 3-5, inhibits
bacterial growth; sebum
contains chemicals toxic
to bacteria
Stomach
– concentrated
HCl and protein
digesting enzymes
Saliva
and lacrimal fluid
contains lysozyme which
destroys bacteria
Sticky
mucus traps
microorganisms
MACROPHAGES
Derived
from monocytes
Free MAC wander all
over
Kupffer
cells -liver
Alveolar cells – Lungs
Permanent residents
WBC
that can
phagocytize
Neutrophils
release
defensins – kills
everything around it,
including itself
WBC
Defend
against parasitic
worms by surrounding it
and discharging
enzymes
Some
bacteria can
replicate inside MACs,
MACs are stimulated to
release other chemicals
(Nitric oxide)
Police
the body
Checks markers –
releases cytolytic
chemicals
Prevent
Spread of
damaging agents
Dispose
of cell debris
Set
stage for repair
 Enhance
the body’s
nonspecific defenses by
attacking microorganisms
or hinder their ability to
reproduce
Classical
– Binding of
antibodies
Alternative – Certain
protein factors are
initiated
 Convergence
on C3,
Splitting it, C3a, C3b.
Initiates events that cause
lysis, promotes
phagocytosis and enhances
inflammation
Message
to tell other
cells there is a virus
Those cells synthesize
“PKR” which interferes
with viral replication
Pyrogens
Pyro
– fire
Causes
liver/spleen to
retain zinc/iron
Helps
speed up
metabolic rate of cells
Can
denature bacterial
enzymes
Advanced Biology
Chapter 22
Specific Body Defenses:
Immunity
Immune
Response
Good
 To
mount an immune
response is expensive. Lots
of energy is required.
Being specific, energy is
only expended when
necessary.
Study
of Immunity
Antigen-Specific
Systemic
Memory
Humoral
(Antibodymediated)
Cellular (Cell-mediated)
Intruders
Not
self
Immunogenicity
–
stimulate the
proliferation of specific
lymphocytes and
antibody production
Reactivity
– Ability to
react with lymphocytes
or antibodies
Part
of antigen that is
immunogenic
Binds to it
Self-antigen
Major
Histocompatibility
Complex (MHC)
Class
I MHC – All body
cells
Class II MHC – Immune
Response Cells
Antigen
(APC)
Presenting Cells
B
Lymphocytes
(Humoral)
T
Lymphocytes (Cell
mediated)
To
be able to recognize
a specific antigen
Eliminates
them
 Before
meeting antigen
 It is in your genes
 An antigen only determines
which B or T cell will
proliferate and attack
Engulfs
antigen, shows
it to a T cell
Advanced Biology
Chapter 22
Humoral Immune
Response
Not
a game show 
st
1
Encounter b/w
immunocompetent
lymphocyte and invading
antigen
3
to 6 Days
Takes time for B cells to
differentiate
2ndry
much faster, more
prolonged and more
effective. 2-3 day
response
See pg 775
The
capacity to produce
a powerful 2ndry
humoral response
When
B cells encounter
antigens and produce
antibodies against them
Naturally
acquired:
During bacterial & viral
infections
Artificially
acquired:
Through vaccine
Dead
or attenuated
(living but weakened)
pathogens
Spare
us from most of
the symptoms
Provide functional
antigenic determinates
No
memory is
established
Fetus to mother
Immunoglobulins
IgD
– Attaches to B
cells, activates B cells
 IgM
– Large, pentamer
shape. Antigen receptive,
st
1 Ig released during
primary response. Fixes
and activates complement
 IgG
– Most abundant – 7585%. Crosses placenta,
protects against bacteria,
viruses and toxins. Fixes
complement.
IgA
– Dimer (2), found
in body secretions, helps
prevent attachment of
pathogens to epithelial
cells
IgE
– Stem region is
bound to mast cells and
basophils (allergies)
Antigen-Antibody
complexes
Complement
Neutralization
– blocks
specific sites on viruses
and bacteria
Agglutination
–
Clumping of cells
 Precipitation
– not rain.
 Antigen molecules, not
cells, are clumped
together.
 See page 780.
Advanced Biology
Chapter 22
Cell-Mediated Immune
Response
Microorganisms
that slip
inside body cells
Trying to avoid immune
system
CD4
= T4, Helper Ts
CD8 = T8, Cytotoxic Ts
Through
processed parts
on an APC
 Provide
means for signaling
to immune system cells
that infectious
microorganisms are hiding
in body cells
Step
1: Antigen Binding
T cell antigen receptors,
TCRs, bind to an
antigen-MHC protein
complex
Helper
Ts bind to MHC
II – w/help of APC
Cytotoxic Ts bind to
MHC I – needs no APC
 Step
2: Costimulation
 If bound to right
costimulator (protein,
chemicals), stimulation
(proliferation) occurs. W/O
right match, T cell activity
is stopped
Mediators
involved in
cellular immunity
Lymphokines
– released
by activated T cells
Monokines – secreted by
MACs
Interleukin
1 & 2 – IL 1
released by MACs tells T
cells to liberate IL 2,
which encourages T cells
to divide more rapidly.
Tumor
Necrosis Factor
(TNF) – enhances
nonspecific cell killing
Perforin/lymphotoxin
are
cell toxins that T cells
can release. Lethal Hit.
Gamma
Interferon –
enhance killing power of
MACs
Regulatory
cells
Interact with B cells
 Major
function is to
chemically or directly
stimulate proliferation of
other T cells and B cells
that have already become
bound to antigen
W/O
helper Ts, there is
no immune response!!
Killer
T cells
They can directly attack
and kill other cells
 Main
target is virus infected
cells, also tissue cells that
have been infected,
parasites, cancer cells,
foreign cells introduced by
blood transfusions or organ
transplants
Help
stop immune
response after antigen
has been destroyed
Promote
reactions
allergic