Topic 2C- Cells and the Immune System Part 2 Flashcards
What happens when an antigen enters the body for the first time?
What is this called?
Why is this process slow?
What will the body eventually do?
What will the infected person do in the meantime?
What two things happen to the immune system after being exposed to an antigen?
How long do these cells remain in the body?
What is the function of memory T-cells?
What is the function of memory B-cells?
What is the person now described as and explain?
It activates the immune system
The Primary Response
Because there aren’t many B-cells that can make the antibody needed to bind to it
Produce enough of the right antibody to overcome the infection
The infected person will show symptoms of the disease
Both T-cells and B-cells produce memory cells
These memory cells remain in the body for a long time
Remember the specific antigen and will recognise it a second time round
Record the specific antibodies needed to bind to the antigen
The person is now immune- their immune system has the ability to respond quickly to a second infection.
What happens if the same pathogen enters the body again (a second time round)?
What is this called?
What occurs faster in this process?
What two things do memory B-cells do in this process?
What two things do memory T-cells do in this process?
What does this process often do before what?
The immune system will produce a quicker, stronger immune response
The Secondary Response
Clonal selection happens faster
Memory B-cells are activated and divide into plasma cells that produce the right antibody to the antigen
Memory T-cells are activated and divide into the correct type of T-cells to kill the cell carrying the antigen
The Secondary Response often gets rid of the pathogen before you begin to show any symptoms.
What can some pathogens change?
What is this called and explain it?
What does this mean happens when you’re infected for a second time?
What does this mean that the immune system has to then do?
What does this response take and so what is the result?
What does antigenic variation also make difficult?
Give two examples of pathogens that show antigenic variation?
Some pathogens can change their surface antigens
Antigenic variation- different antigens are formed due to changes in the genes of a pathogen
The memory cells produced from the first infection will not recognise the different antigens
Start from scratch and carry out a primary response against these new antigens
The primary response takes time to get rid of the infection, which is why you get ill again
Antigenic variation also makes it difficult to develop vaccines against some pathogens for the same reason
HIV and the Influenza virus.
Describe the five stages of how antigenic variation affects the production of vaccines to help prevent people catching influenza?
- The influenza (flu) virus changes every year. That’s because the antigens on the surface of the influenza virus change regularly, forming new strains of the virus
- Memory cells produced from vaccination with one strain of the flu will not recognise other strains with different antigens. The strains are immunologically distinct
- Every year there are different strains of the influenza virus circulating in the population, so a different vaccine has to be made
- New vaccines are developed and one is chosen every year that is the most effective against the recently circulating influenza virus
- Governments and health authorities then implement a programme of vaccination using the most suitable vaccine.
What do vaccines contain and what does this cause?
What does this mean?
Who do vaccines protect?
Why do vaccines protect those that aren’t vaccinated?
What is this called?
What are the two types of antigens present in vaccines?
What are the two ways that vaccines may be taken?
Antigens that cause your body to produce memory cells against a particular pathogen, without the pathogen causing disease
This means you become immune without getting any symptoms
Vaccines protect individuals that have them
Because vaccinated people reduce the occurrence of the disease, those not vaccinated are less likely to catch the disease
Herd immunity
Free or attached to a dead or attenuated (weakened) pathogen
Injected or taken orally.
What are the two disadvantages of taking vaccines orally?
What type of vaccines are given later on?
Why is this?
- It could be broken down by enzymes in the gut
- The molecules of the vaccine may be too large to be absorbed into the blood
Booster vaccines are given later on (eg after several years)
To make sure that memory cells are produced
What is the full definition of active immunity?
Describe natural active immunity?
Describe artificial active immunity?
This the type of immunity you get when your immune system makes its own antibodies after being stimulated by an antigen
Natural- when you become immune after catching a disease
Artificial- when you become immune after being vaccinated containing a harmless dose of antigen.
What is the full definition of passive immunity
What doesn’t the immune system do in passive immunity?
Describe natural passive immunity?
Describe artificial passive immunity?
Give an example of artificial passive immunity?
This is the type of immunity you get from being given antibodies made by a different organism
The immune system doesn’t produce any antibodies of its own
Natural- when a baby becomes immune due to the antibodies it receives from its mother, through the placenta and in breast milk
Artificial- when you become immune after being injected with antibodies from someone else
eg if you contract tetanus you can be injected with antibodies against the tetanus toxin, collected from blood donations.
