Keeping healthy Flashcards
Microorganisms that cause disease are called
pathogens
Bacterial infections cause symptoms by
Release of toxins
Name some bacterial infections
Salmonella food poisoning; tetanus; bacterial meningitis; gonorrhea; syphillis
Viral infections cause symptoms by
damage to cells as the virus takes it over to reproduce
Name some viral infections
Ebola, common cold, flu, measles, chickenpox, genital herpes
How do bacteria reproduce?
They divide themselves in two
What is the type of reproduction where a cell divides itself in two called?
Binary fission
What type of population growth is produced by bacteria
Rapid, called exponential growth as the number doubles each time they go through their reproductive cycle.
How do viruses reproduce?
They need a host cell, which they enter and “hijack” to produce extra copies of themselves.
Can viruses reproduce without host cells?
No
What are our external defences against infection?
eg Skin; saliva; tears; stomach acid
What is our internal defence against infection?
The immune system.
What type of cells does the immune system use?
White blood cells
Where are white blood cells made?
The bone marrow
What do white blood cells do?
Some engulf and digest invading microorganisms while others produce antibodies.
What is an antibody?
A protein that “fits” onto a protein (an antigen) on the invading cells surface.
How many antigens can one antibody fit?
One
Where is the antibody found?
On the surface of a white blood cell
What happens when an antibody locks onto an antigen?
The white blood cells divides to produce multiple copies of itself. Each white blood cell produces multiple copies of the antibody.
What do antibodies do?
They can destroy the invading organism; enable the white blood cells to recognise the foreign invader; cause the microorganisms to clump together, making it easier to engulf them all.
What happens after the body has managed to fight off the invading microorganisms?
Memory cells remain in the bloodstream
What do memory cells do when the microorganism that they “remember” is encountered?
They produce large numbers of the correct antibody very quickly.
If you have memory cells for a specific infection you are said to be?
Immune
What does a vaccine contain?
A safe form of the pathogen
What happens after vaccination?
The immune system attacks the pathogen and memory cells will remain in the bloodstream
What do vaccination programmes do?
They are designed to protect the target population against a specific illness.
Why is a new flu vaccination required every year?
The flu virus mutates rapidly, so it has new antigens on the surface and it is necessary for our immune system to create the new antibodies
Why are some vaccinations not repeated?
The organism concerned does not mutate much so the antibodies remain effective against the antigens on its surface
What is an epidemic?
A disease that is spreading rapidly
How does vaccination stop epidemics?
If enough people in the population are immune then there are not enough people who will catch the disease for it to spread. This is called “herd immunity”. This means that even people who cannot be vaccinated are still protected as there is no one to catch the illness from.
Can vaccination eradicate diseases?
Yes, smallpox has been eradicated.
Why is it necessary to test vaccinations?
They can have side effects.
Are side effects always the same?
No, people have different side effects due to genetic variations.
Is it possible to be certain that a vaccine is safe for everyone?
No, it is not possible to test it on all genetic variations.
Is any medical treatment risk-free?
No, there will always be small risks, but people often perceive the risks as being greater than they are.
Are vaccinations safe?
Yes. (For this exam!) Millions of people have benefited.
What can happen as a result of vaccination?
Occasionally the person may develop a rash or a fever. Rarely, a more serious adverse reaction may take place.
What would happen if a vaccine caused a lot of adverse reactions?
The risks would be assessed against the benefits, and it might be withdrawn.
What would you call a drug to kill bacteria, viruses or fungi?
An antimicrobial.
What do you call a drug to kill bacteria?
Antibiotic.
What is the word for microorganisms no longer being affected by a drug?
Resistance
What are the implications of microorganisms being resistant to drugs?
Some infections are very difficult to control. This microorganisms are most likely to be found where the drugs are used frequently, eg hospitals.