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15 Cards in this Set

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What is an anti-biotic? What does it do?
Antibiotics are substances that kill bacteria or stop their growth. They do not work against viruses: it is difficult to develop drugs that kill viruses without also damaging the body’s tissues
What is a pathogen?
Microorganisms that cause infectious disease.
What are the features of bacteria?
Cell wall, cell membrane, cytoplasm, chromosome
What are the features of virus'?
Chemical hooks and drills, DNA strand and Protein coat.
What is the first way your body protects itself from pathogens? How?
Passive immunity, stopping the pathogen getting into the body in the first place. The body’s passive immunity system includes the skin, mucus and cilia in the respiratory system, acid in the stomach, and enzymes in tears.
What is the second defence called?
Active Immunity
What do white blood cells do?
They can ingest pathogens and destroy them
produce antibodies to destroy pathogens
produce antitoxins that neutralise the toxins released by pathogens.
What do phagocytes do?
Phagocytes can easily pass through blood vessel walls into the surrounding tissue and move towards pathogens or toxins. They then either:

ingest and absorb the pathogens or toxins, or
release an enzyme to destroy them.
Having absorbed a pathogen, the phagocytes may also send out chemical messages that help nearby lymphocytes to identify the type of antibody needed to neutralise them.
What do lymphocytes do?
Phagocytes can easily pass through blood vessel walls into the surrounding tissue and move towards pathogens or toxins. They then either:

ingest and absorb the pathogens or toxins, or
release an enzyme to destroy them.
Having absorbed a pathogen, the phagocytes may also send out chemical messages that help nearby lymphocytes to identify the type of antibody needed to neutralise them.
How do antibodies neutralise antigens?
They bind to pathogens and damage or destroy them.
They coat pathogens, clumping them together so that they are easily ingested by phagocytes.
They bind to the pathogens and release chemical signals to attract more phagocytes.
Lymphocytes may also release antitoxins that stick to the appropriate toxin and stop it damaging the body.
What does vaccination involve?
A weak/ dead form of a pathogen being injected into the body and acting as a pathogen.
The white blood cells respond to the presence of the pathogen and identify the antibody to destroy the pathogen. Then it leaves memory cells around so that next time a real pathogen of that disease enters the body, the body is ready.
Name a common antibiotic
Penecillin
What do bacteria do to become resistant to antibiotics?
Bacterial strains can develop resistance to antibiotics. This happens because of natural selection. In a large population of bacteria, there may be some cells that are not affected by the antibiotic. These cells survive and reproduce, producing even more bacteria that are not affected by the antibiotic.
Why is it important that we don't overuse antibiotics?
Because then we can slow down, or stop, the development of other strains of resistant bacteria.
Why didn't people believe Semmelweiss?
Because they didn't know pathogens could be killed.