Infection and response 2 Flashcards
Defence systems, Monoclonal antibodies, Medicine.
What non-specific defence systems does the human body use to prevent pathogens from getting in?
-Skin
-Mucus in nose, trachea, and bronchi
-Cilia in the trachea and bronchi
-Stomach acid
How does the skin stop pathogens?
-It’s a physical barrier
-It secretes antimicrobial substances which kill pathogens
How do cilia stop pathogens?
Move the mucus up to the back of the throat where it can be swallowed
How does mucus stop pathogens?
Trap particles that could contain pathogens
How does the stomach prevent pathogens making us ill?
Produces hydrochloric acid which has a low pH of 2, killing pathogens.
What is the role of the immune system?
To destroy a pathogen if it enters the body.
What is the most important part of the immune system?
The white blood cells
What is the function of white blood cells?
-Phagocytosis to destroy pathogens
-Producing antitoxins to counteract toxins released by pathogens
-Producing antibodies to destroy specific pathogens
What is an antitoxin?
A substance that neutralises toxins produced by pathogens (bacteria) by binding to them.
What are antibodies?
-Small y-shaped proteins that bind to specific foreign antigens on the surface of pathogens
-This signals our immune system to destroy the pathogen
-Produced by Lymphocytes
What are memory cells?
The WBCs which remember how to make specific antibodies.
What is the secondary immune response?
The second time the body is exposed to a specific antigen, WBCs will produce antibodies much faster and in greater numbers than before.
So, they destroy the pathogen (hopefully) before a person develops symptoms - this is known as immunity.
This is because memory cells remember how to make the specific antibodies for that antigen.
What is the first response to an infection and why?
A fever. The higher temperatures denature pathogen enzymes, slowing the pathogen down.
However, normal enzymes will also be denatured making us feel ill.
What happens during phagocytosis?
A phagocyte goes to the area of infection and engulfs a pathogen, which it recognises as foreign. It then releases enzymes to digest the pathogen.
What is an antigen?
A specific protein found on the surface of a pathogen.
What does a vaccination contain?
A small amount of the dead or weakened form of a pathogen.
How does a vaccine work?
-Vaccination involves introducing a small amount of the dead or weakened form of a pathogen into the body.
-These carry antigens
-This stimulates your WBCs to produce antibodies against that specific pathogen
-If live pathogens of the same type enter the body, WBCs will produce more antibodies more quickly to destroy the pathogen
-It will be destroyed before the individual gets any symptoms
-We can say the individual is immune
How can the spread of pathogens be reduced by immunising a large proportion of the population?
Even people who aren’t vaccinated are unlikely to catch the disease because there are fewer people available to pass it on. This is known as ‘herd immunity’.
Briefly explain the process of vaccination.
Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies.
If the same pathogen re-enters the body, the white blood cells respond quickly to produce the correct antibodies, preventing infection.
Pros of vaccination
-You can control communicable diseases that were once common, e.g. smallpox
-You can prevent epidemics via herd immunity
What may happen if a significant number of people aren’t vaccinated?
A disease can spread quickly through them and lots of people can become ill at the same time.
Cons of vaccination
-Vaccines don’t always work/give people immunity
-You can sometimes have a bad reaction to a vaccine.
Specific bacteria should be treated by…
…specific antibiotics because different ones kill different types of bacteria.
Why are antibodies a specific defence?
Antibodies must be the correct shape, complementary to the pathogen’s unique antigens, so they target a specific pathogen.
What are painkillers?
Drugs that reduce the symptoms of a disease but do not kill pathogens.
-Other drugs can do this to e.g. ‘cold remedies’
What are antibiotics?
Medicines that help to cure bacterial disease by killing (or preventing the growth of) infective bacteria inside
the body - without killing body cells.
Why can’t antibiotics kill viral pathogens/be used to treat viral diseases?
Viruses reproduce using you body cells which makes it difficult to develop drugs that destroy just the virus without killing the body’s cells.
What has the use of antibiotics done?
The use of antibiotics has greatly reduced the number of deaths from infectious bacterial diseases.
How do strains of bacteria become resistant to antibiotics?
Bacteria can mutate and sometimes these mutations cause them to be unable to be killed an antibiotic (resistant).
Why is the emergence of bacterial strains resistant to antibiotics of concern?
-When you treat an infection with antibiotics, only non-resistant strains of the bacteria will be killed
-The individual resistant bacteria will survive and reproduce by binary fission
-The population of the resistant strain will increase due to natural selection
-The resistant strain could cause a serious infection that can’t be treated by antibiotics
How can we slow the development of resistant strains of bacteria?
-Doctors shouldn’t over prescribe antibiotics
-Finish the whole course of antibiotics
What is Digitalis?
-A drug used to treat heart conditions
-It was developed from a chemical in/originates from foxgloves (plant)
What is Aspirin?
-A painkiller, also used to lower fever
-It was developed from a chemical found in willow
Why are many drugs extracted from plants?
-Plants produce a variety of chemicals to defend themselves against pathogens
-Some of these chemicals can be used to treat human diseases or relieve symptoms
What is Penicillin?
-The first antibiotic
-Discovered by Alexander Fleming from the Penicillium mould
How did Alexander Fleming discover penicillin?
-He was cleaning out petri dishes with bacteria on
-One with mould on it had a clear zone around the bacteria
-He found that the mould was producing a substance that killed the bacteria- Penicillin.