3/20 (ODD) 3/23 (EVEN)
Goals: Explain how cells communicate with each
other to maintain defense.
Agenda:
–Ch. 43 notes
–POGIL Immunity
Homework:
1. Immune System Concept Map: can use Cmap
to make digital concept map or on paper
2. Read Ch. 44.
Unit 7: Big Ideas
• Big Idea 1: EVOLUTION—The process of evolution drives the
diversity and unity of life.
• Big Idea 2: CELLULAR PROCESSES: ENERGY AND
COMMUNICATION —Biological systems utilize free energy and
molecular building blocks to grow, to reproduce, and to maintain
dynamic homeostasis.
•Big Idea 3: GENETICS AND INFORMATION
TRANSFER —Living systems store, retrieve,
transmit, and respond to information essential
to life processes.
–Enduring Understanding 3.D: Cells communicate by
generating, transmitting, and receiving chemical signals.
• Big Idea 4: INTERACTIONS—Biological systems interact, and these
systems and their interactions possess complex properties.
Must Knows:
•Several elements of an innate immune response.
•The differences between B and T cells relative to
their activation and actions.
•How antigens are recognized by immune system
cells.
•The differences in humoral and cell-mediated
immunity.
•Why helper T cells are central to immune
responses.
Non-specific Defenses
Animals have a variety of chemical defenses against
infections that affect dynamic homeostasis.
IMMUNE SYSTEMS
Non-specific vertebrate defenses
All organisms have non-specific defenses
(innate immunity).
These are considered your first line of
defense against disease.
This protection is always the same no
matter what the invader may be.
External: Skin, mucous, lysozymes in: tears,
saliva, and sweat.
Internal: Inflammatory response.
Non-specific
defenses
Phagocytes
(neutrophils &
macrophages) are
white blood cells
that engulf
pathogens that are
broken down using
lysosomes or
peroxisomes.
Non-specific defenses
Natural Killer cells: WBC’s that target certain
tumor cells and virus-infected cells without the
stimulation of antigens, and kill them by the
insertion of granules containing perforin.
They act as your
second-line of
defense against
disease.
Mammalian Specific Immunity
Mammals have a highly developed specific
immune system (third line of defense).
Specific and Non-Specific Interactions
The specific immune response is triggered when
non-specific phagocytes present antigens (surface
proteins on a pathogen) to lymphocytes.
Controlled by
lymphocytes:
B cells and T cells
2 major divisions:
• Humoral
• Cell-mediated
Specific and Non-Specific Interactions
Interferons – chemicals released from damaged, invaded
cells used to warn other cells of incoming danger—other
cells increase their defenses to interfere with the ability to
be attacked.
“SAVE YOURSELF” proteins
Humoral Response
A B cell binds antigen to it’s
receptor, internalizes it, and
presents it on MHC II.
A helper T cell recognizes
the MHC II–antigen complex
and activates the B cell to
produce memory B cells
and plasma cells.
MHC II – All WBC’s possess
these. MHC II holding an
antigen shows other WBC’s
what to look for and kill.
Humoral Response
Memory B cells will remain alive and available in the
immune system for future exposure to the same antigen.
Subsequent exposures will trigger a faster and larger
immune response.
Antibody Structure
T-cells and B-cells have specific receptors
on their cell membranes that respond to
specific antigens.
Clonal Selection
When lymphocytes mature,
those that have receptors
that react with “self”
molecules are eliminated.
When lymphocytes are
presented with an antigen,
only those with reactive
receptors are allowed to
reproduce.
Humoral Response
Plasma cells (effector cells)
produce and secrete antibodies
that bind to specific antigens.
Plasma cells secrete about 2,000
antibodies per second.
Somatic
recombination of
different segments of
the B-cell and T-cell
receptor genes
generates many
thousands of
different possible
antigen binding sites.
Antibody Action
Antibodies work by
binding to antigens on
pathogens and target
them for destruction
by T-cells, phagocytes,
or prevent them from
continuing their life
cycle.
Blood
Types
Cell-Mediated Response
Specific T-cells are developed to target specific
antigens and trigger the destruction of those
pathogens and infected cells through cell-cell
interactions.
Blood transfusions
and organ donations
are dependent upon
the antibodies
present in the
plasma of the
recipient.
Blood cells with
antigens that match
the antibodies will
bind and clump in
the blood and block
vessels.
Helper T Cells: Activate both B and cytotoxic T cells.
Cytokines - chemical messengers that regulate cell
differentiation (form and function), proliferation (production),
and gene expression to affect immune responses.
HIV/AIDS
HIV is the virus that
causes AIDS.
It brings about the
destruction of the
immune system by
infecting and killing
helper T cells —
which are central in
both humoral and
cell-mediated
immunity.
Cytotoxic T cells: Release perforin to destroy body
cells that are infected by a pathogen or cancer cells.
MHC I – All cells other than WBC’s possess these. MHC I
placed on the cell surface holding an antigen tells WBC’s
that the cell itself is infected.
Anaphylaxis
Some people who are allergic to bee
stings experience anaphylactic shock.
Epinephrine Treatment
Causes constriction, or tightening, of the blood vessels,
which decreases swelling and also helps to increase
blood pressure.
Increases the heart’s contraction and heart rate, which
can help to prevent or reverse cardiovascular collapse.
Relaxes muscles around the airways in the lungs,
helping the airways to open up.
Prevents the release of additional allergic chemicals,
which aids in stopping further progression of the
reaction.
Wrap-up:
1. What are some examples of innate
immunity?
2. Describe the function of the following:
– Plasma cells
– Helper T cells
– Cytotoxic T cells