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Biology
I will understand the role of antibodies (molecular barrier) in the body's response to infection and based on this, know how a vaccine works.
MT: Immune System
Above: measles rash
Below: muscle spasm from tetanus
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40-2 The Immune System
What is the function of the immune system?
To protect against pathogens.
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3. 40-2 The Immune System
The immune system includes two general categories of defense mechanisms against infection:
Specific defense
Non-Specific defense
Only detects certain pathogens
Does not discriminate against pathogens – kill all pathogens
Ex: antibodies, T cells, B cells
Ex: skin, mucous, sweat glands, tears
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What is an antigen?
Antigen: any pathogen that activates the immune system
Ex: virus, bacteria
Antibodies attack antigens
bad
good
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5. AntiBODY = good protein AntiGEN = bad pathogen
Antibody vs. Antigen
AntiBODY = good protein
AntiGEN = bad pathogen
Antibody
Antigen
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6. Steps to making an Antibody
Pathogen (antigen) gets past skin, mucous, or tears into blood
Antigen is detected by B-cells (a type of white blood cell)
B-cells reproduce rapidly
Some B-cells become plasma cells
Some B-cells become memory cells
Plasma cells release antibodies to attack antigens
Memory cells stay in blood and hang out until the body is exposed to same antigen later so it can rapidly produce antibodies
As antigens die, plasma cells die and stop producing antibodies
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Antibody structure
Antigen binding site
An antibody is shaped like the letter “Y” and has two identical antigen- binding sites.
Antibody
Antigen
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Specific Defenses
Small differences in amino acids affect shapes of binding sites.
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How does a vaccine work?
Vaccines (a weakened form of a pathogen) stimulate the immune system to create millions of plasma cells ready to produce specific types of antibodies.
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Acquired Immunity
Today, over 20 serious human diseases can be prevented by vaccination including:
1. measles (respiratory; coughing; virus)
2. mumps (swollen salivary glands or testes; virus)
3. hepatitis (inflammation of liver, mostly virus)
4. tetanus (severe muscle spasms; bacteria)
5. polio (muscle weakness; attacks nerves; viral)
(Franklin D. Roosevelt)
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