Transcript LN #13 Immune

Immune Response
LN #13
Body Response
• Your body responds to
pathogens in several
different ways.
• Body has specific
responses and
nonspecific responses
• Specific responses
– Occur at cellular level;
different for each pathogen
• Nonspecific responses
– Same for every pathogen
– Imflammation and fever
Nonspecific Response:
Inflammation
•Pin breaks the
skin and infects
with bacteria.
•The damaged
cells release
chemical alarm
signals.
Blood
flow to the
area increases and
causes swelling.
Chemicals attract
phagocytes and
other white blood
cells to the area.
•Phagocytes
destroy the
bacteria.
Nonspecific Response: Fever
• White blood cells (mast cells or macrophages)
signal the brain to increase the bodies
temperature until the infection is controlled.
• Low fevers 100°F (37.7°C)
– Stimulate production of Interferons (prevent viruses
from reproducing)
– Increase activity of white blood cell maturation
• High fevers 103°F (39°C)
– Are dangerous
– Enzymes stop functioning
– Can cause seizure, brain damage and death
Specific Response
• Lead to acquired immunity
• Occur at cellular level
• For specific responses to work your body
needs to be able to tell the difference
between your cells and pathogens.
– Antigens are protein markers on the surface
of cells and pathogens. They help your body
identify your cells and pathogens.
Specific Immune Response
• Depends on T cells
• There are two types: helper and killer
• Helper T Cell
– Function: activates B cells and killer T cells
– Helper T cells also need to be activated by
binding to antigens on the surface of
phagocytes
Helper T Cell Activation
1. A phagocyte “eats” a bacteria
2. Parts of the bacteria (antigen) goes into the surface of
phagocyte
3. Phagocyte presents the antigen to helper T cell
4. Helper T cell is activated and goes on to activate B
cells and killer T cells
Killer T Cells
•
•
•
•
Activated by helper T Cells
Specialized to attack infected body cells and cancer cells
Recognizes infected cells by the antigens on its surface.
Once a cells is recognized as infected it is quickly killed.
B cells
1. The B cell finds an antigen which matches its
receptor
2. It waits until it is activated by a helper T cell
3. Then the B cell divides to produce plasma and
memory cells
B Cells in Action
4. Plasma cells produce antibodies that attach to the
current type of invader
5. “Eater cells” prefer intruders marked with antibodies,
and “eat loads of them
6. If the same intruder invades again memory B and T
cells help the immune system attack much faster
Lymphatic System
• Function
– Site where B and T
cells migrate to
– Transportation and
storage of B and T
cells
– Filters out dead cells
and invading
pathogens