Transcript Immune System Introduction

Immune System
Overview Flow Chart
CA Biology Standards
Physiology 10a & 10d
Physiology Standard 10b
Students know the role of
antibodies in the body’s
response to infection.
Non-Specific Immunity
Defenses that are NOT designed to fight a specific
disease, but ALL diseases!!

Chemical & Physical Barriers Include:
1. Skin – Most important first line of defense.
Physical barrier that keeps pathogens out!
2. Mucus – Contains enzyme (lysosyme) that
break down cell walls of many bacteria
3. Sweat & Tears – Contains lysosyme and
promote acidic environment that bacteria
cannot survive
What if the 1st line of defense
doesn’t do the job?
4. Inflammatory Response: A non-specific defense
reaction to tissue damage caused by injury or
infection.
a. White Blood Cells (Phagocytes) – Detect, engulf
and destroy pathogens
b. Fever- Elevated body temperature kills or slows
down growth of pathogens
5. Interferons- Proteins produced by virusinfected cells. Help other cells resist viral
infections.
Specific Immunity

Triggered by specific Antigens to produce
Antibodies
– Antigen – A foreign substance that triggers an
immune response.

Two Types of Responses:
1. Humoral Response
 “Humoral” = In blood or lymph
2. Cell-Mediated Response
Humoral Response
1. In the Blood & Lymph
a. Lymphocytes produce antibodies
2. Antibodies are Y-Shaped Proteins that
help to destroy pathogens
a. Pathogens are foreign threats
the body (virus, bacteria, etc)
b. Antibodies bind to antigens
the pathogens
c. Cause pathogens to
clump up
Antigenbinding
sites
to
on
Antigen
Antibody
Humoral Response
3. White blood cells engulf and destroy pathogens
(clumps of antibodies & antigens)
4. B cells can be activated by T cells to turn into
plasma cells.
5. Plasma cells produce and release large numbers
of antibodies into the bloodstream.
6. Some B cells become Memory Cells and can
quickly respond if reinfected by same antigen
(you can’t get the same cold twice)
Humoral Response
Cell-Mediated Response
1. Killer T cells kill infected cells to inhibit
the reproduction and spread of viruses
Killer T cells are also called Cytotoxic T cells
2. Causes body to reject transplanted
organs
Cell-Mediated Response
Figure 40-10
Macrophage
T cell binds to
activated
macrophage
Helper T cell activates
killer T cells and B cells
Helper
T Cell
Killer
T Cell
T Cell
Antigens are displayed
on surface of
macrophage
T cell, activated by
macrophage, becomes a
helper T cell
Infected Cell
Killer T cells bind to infected
cells, disrupting their cell
membranes and destroying them
Vocabulary
Pathogens
 Viruses
 Bacteria
 Antiseptics
 Antibiotics
