Transcript The Immune System - Blue Valley School District

The Immune System
Function
• The immune system functions to
provide protection from disease causing
agents in the one’s environment
• Pathogens include viruses, bacteria,
fungi, protistans, and various parasitic
animals
Lines of Defense
Innate Immunity – non-specific through a
variety of mechanisms
1. Surface Barriers
2. Internal Defense
Acquired Immunity – specific through
special lymphocytes
1. Humoral Response – B Cells
2. Cell Mediated Response – T Cells
Innate Immunity:
Surface Barriers
• Skin with low
moisture, low pH,
thick layers of dead
cells, and resident
bacterial fauna
• Mucous membranes
with low pH,
lysozyme, and
flushing action of
secretions
Innate Immunity:
Internal Defense
•
1.
2.
3.
4.
The internal defense mechanisms of the innate
immune response has a number of components,
that may act in concert to defeat the foreign
pathogen.
Phagocytic cells
Complement proteins
Inflammation
Natural Killer Cells
http://www.muhealth.org/~pharm204/inflammation.mov
Inflammation
In reaction to tissue damage or cell death mast
cells release histamine which induces
dilation in the surrounding capillaries and
indirectly the four symptoms of
inflammation:
1. Swelling
2. Reddness
3. Warmth
4. Pain
Phagocytic Cells
There are a variety of
phagocytic cells that
include:
• Neutrophils
• Eosinophils
• Basophils
• Macrophages
Compliment Proteins
• Actived plasma proteins
create a Cascade of
other proteins to form
that produce pore
complexes that induces
lysis and death in
cellular pathogens
• Bound complexes also
promote phagocytosis
Acquired Immunity
• Becomes activated as
physical barriers and
inflammation fail.
Phagocytic cells
produce cytokines that
initiate the acquired
immune response.
• Specialized
lymphocytes called B
and T-cells initiate the
humoral and cellmediated responses,
respectively.
General Mechanism
Pathogens stimulate the
mitotic production of:
Effector cells that reduce
the pathogen
• Helper T Cells
• Cytotoxic T Cells
• B Cells
Memory cells that remain
in prepared for later
infections by the same
pathogen
Antigen Presentation
In this process
macrophages
1. engulf,
2. process, and
3. presents the
pathogens antigens in
their MHC markers
(surface proteins) to
the immune system.
Helper T-Cells
•
Antigen
presentation
activates Helper TCells which
subsequently are
involved in
activating Cytotoxic
T-Cells and BCells.
Cytotoxic T-Cells: Cell
Mediated Response
•
T-cells mature in the
Thymus and take
residence in the
lymphatic system at
maturity
• Effector Cytotoxic Tcells secrete
1. Perforins (pore
producing chemical)
and
2. Apoptosis inducing
chemicals
B-Cells: Antibody Response
• B-cells mature in the
bone marrow
• Effector B-cells secrete
a diversity of “Y” shaped
proteins called
antibodies binding
• Antibodies bond to
antigens and set them
up for destruction by
macrophages