Immune System Guided Notes
Name:_____________________
Do Now
What is the difference between the non-specific and specific defense system?
Which one is activated by vaccines?
The specific defense system
The specific defense system (aka immune system) recognizes and attacks specific pathogens.
The immune system has 3 important characteristics:
» Antigen-specific
» Systemic
» Has memory
What are antigens?
What does systemic mean?
Cells (and chemicals) of the immune system
»
_________________________________
•
_________________________________ function in non-specific defense* to kill virus
infected or cancerous body cells
•
________________________________ mature in bone marrow. They become
activated by binding to specific antigens then divide to form:
•
•
_______________________ which release antibodies
•
_______________________ which ‘remember’ specific antigens
_______________________ mature in the thymus. They become activated by binding
to specific antigens then divide to form:
•
________________________________________ kill virus infected or
cancerous body cells
•
_______________________________________ stimulate the production of
immune cells and release chemicals which help destroy pathogens
•
_______________________________________ stop activity of immune cells
after infection is over
•
_______________________________________ ‘remember’ specific antigens
What do the B and T refer to?
Which cell has a similar function to NK cells? How are these two cells different?
Which cells directly attack pathogens?
»
_______________________________________________
•
»
»
Play a role in non-specific AND specific defense system
•
______________________________________________________________
(non-specific system)
•
Act as ________________________________ (specific system) by displaying
fragments of these particles on their surface and activating T lymphocytes.
Antibodies
•
Proteins produced by plasma cells (B cells) that bind to specific antigens
•
Binding of antibodies to pathogen causes their destruction / inactivation in one of a few
ways
•
_____________________________________: Encourages other chemicals
(complements) to punch holes in the surface of the pathogen, destroying it.
•
_____________________________________: Binding prevents viruses or
toxins from entering healthy body cells
•
____________________________________: clumping of antibody-bound
particles, which makes them unable to enter healthy cells and more likely to be
eaten by phagocytes
•
______________________________________ – the presence of antibodies
‘flags’ a pathogen, increasing the chance that it will be eaten by a phagocyte.
Other important chemicals
•
______________________________ – proteins that in blood that bind to pathogens;
activity increased by presence of antibodies
•
________________________________ – proteins that bind to virus-infected cells and
reduce the ability of viruses to multiply; also work with T cells to increase recognition of
virus infected or cancerous cells.
•
________________________ and _____________________ – cause inflammatory
response
•
______________________ and ______________________ – released by T cells,
increase immune response and directly destroy pathogens
Circle the chemicals you need to know!
Two branches of the Immune system
There are two branches of the immune system:
»
The ________________________________________________ which involves the production of
_________________________ that fight ___________________________________________
(pathogens including viruses and bacteria that are among our cells, but not inside them).
»
___________________________________________________ which involves the activation of
________________________________ that destroy _________________________________
and ___________________________________.
The story of the lucky lymphocyte
The body naturally produces a HUGE array of B- and T- lymphocytes, with widely diverging receptors.
Each receptor is capable of binding with only one type of antigen. These mature, but inactive,
lymphocytes take up residence in lymphatic organs and wait to meet their antigen.
Most never will.
The lucky few lymphocytes that do bind to their antigen will undergo clonal selection so that they, and
their multitude of offspring, can fulfill their destiny by participating in the humoral or cell-mediated
immune response.
Humoral Immune Response
1. B-lymphocytes bind to specific, free-floating
antigens and become activated.
2. The activated B-lymphocyte divides many
many times, forming identical clones, also
capable of binding to the antigen.
3. Most of these clones will become plasma
cells that specialize in producing antibodies
that bind only with that specific antigen.
4. A few will become long-lived memory cells
that will persist for years, waiting in case the
same antigen is encountered again.
Primary vs. Secondary Humoral Immune Response
»
The primary humoral immune response occurs the first time the immune system encounters a
specific antigen.
Why?
»
The secondary humoral immune response occurs any time after the immune system first
defeats an antigen. This response is much faster and produces more antibodies.
Why?
How does this graph explain the function of vaccines?
Why are booster vaccinations necessary?
Types of acquired immunity
The least common method is artificial passive immunity. Used for exposures / disorders that are likely
to be fatal before the body can mount its own immune defense.
Includes: antivenom, botulism, rabies, & tetanus
Cell-Mediated Immune Response
The humoral immune response involves the production of antibodies and memory B lymphocytes.
What does the cell-mediated immune response involve?
»
T-cell activation
•
Like B-cells, T-cells must bind to their one, specific antigen before they are activated.
•
Unlike B-cells, T-cells cannot bind to free-floating antigens and must bind to an antigenpresenting cell, like a macrophage.
»
Activated T cells will clone (multiply)
»
T cells will do their specific jobs
Types of T cells
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Cytotoxic Ts ____________________________________________________________
___________________________________________________________________________
»
Helper Ts have many jobs
»
•
Encourage __________________________ of activated B cells and cytotoxic Ts
•
Encourage ______________________________________ from plasma cells
•
Release chemicals (lymphokines) which _____________________________and enhance
activity of phagocytes
Suppressor Ts
•
»
Release chemicals that _________________________________________________, to
slow immune response once antigen is destroyed
Memory Ts
•
Long-lived cells that remain for quick response upon subsequent infection
Why might helper Ts be thought of as the bridge between cell-mediated immunity and humoral
immunity?