Transcript First line of defense

The remarkable capacity of the
immune system to respond to
many thousands of different
substances with exquisite
specificity saves us all from
certain death by infection.
- Martin C. Raff
Include:
- Skin
- tears and other secretions
- contain lysozyme (antibacterial)
- inflammatory response
- interferons
- fever
First line of defense
- Skin (acts as physical
barrier)
- Saliva, mucus, and tears
(lysozyme) protect where
skin is not present (mouth,
nose, and eyes)
Second line of defense
1. Inflammatory Response
- infected area becomes red and painful (inflamed)
- mast cells release histamine
- histamines increase blood flow to infected area
bringing phagocytes that engulf bacteria
- local rise in temp.
Chemical signals = histamines
2. Interferons
- proteins produced to interfere with viral
growth
- “buy time” for immune system to respond
3. Fever
- increased body temp.
- may slow growth of pathogen and
speeds immune sys.
• Distinguishes between “self” and “non-self”;
inactivate or kill any foreign substance that
enters body.
- proteins made by individual recognized
as “self”
- Recognize chemical markers, no two
individuals have the same markers
- if markers aren’t recognized, immune
response created
* Respond to a SPECIFIC pathogen!!
Antigens and Antibodies
• antigen = foreign substance that
stimulates an immune response
- outer surface of bacteria, viruses,
parasites
• antibodies = tag antigens for
destruction
- may be attached to cells or free
floating
- 10 billion different ones; each one
binding to a specific antigen
Lymphocytes
• B lymphocytes (B cells)
- produced and mature in
bone marrow
- discover antigens
• T lymphocytes (T cells)
- produced in bone marrow,
mature in thymus
- must be presented with
antigen
• depends on action of antibodies
• antibodies on B cells bind to antigen, T cells
stimulate growth and division of B cell into two
types:
1. Plasma cells
- produce and release antibodies that bind to
specific antigen
2. Memory B cells
- remain alive and react quickly to
secondary response
- produce new plasma cells
- long-term immunity
Humoral Immunity Animation
• action of macrophages and T cells
• when macrophage consumes pathogen a
portion of the antigen is displayed on membrane
surface
• Helper T cells circulate and activate to form
more helper T cells
• Helper T cells activate B cells, cytotoxic T cells,
and make memory T cells
CellMediated
Immunity
Animation
See p. 1018 for more detailed diagram
Other immune cells include:
1. Cytotoxic T cells
- hunt down body cells infected and kill them
2. Suppressor T cells
- inhibit immune response when infection
under control
- may prevent autoimmune diseases
The Immune Response