immunity Flashcards
what is a pathogen?
an organism or virus causing disease
what is an antigen?
a foreign protein that triggers an immune response
what is meant by herd immunity?
when most members of a population are vaccinated so it is difficult for an infected person to pass the infection onto another individual
what is active immunity?
the type of immunity you get when your immune system makes its own antibodies after being stimulated by an antigen
what is passive immunity?
the type of immunity you get from being given antibodies made by a different organism, so your immune system doesn’t produce any antibodies of its own
describe the two types of active immunity
natural
- normal response to infection - this is when you become immune after catching a disease
- body produces its own antibodies
artificial
- introducing an immune response in an individual after being given vaccination
describe the two types of passive immunity
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 or antitoxins from someone else - gives immediate protection
describe the differences between active and passive immunity
- active requires exposure to antigen, passive doesn’t
- in active, memory cells are produced but aren’t in passive
- in passive, the protection is short term as antibodies given get broken down, whereas in active the protection is long term
- with passive, effect is immediate but with active it takes a long time
what is primary immune response?
the first exposure to the antigen
- antibodies are produced slowly & at lower concentration
- memory cells are produced
- takes time for specific B plasma cells to be stimulated and produce specific antibodies
what is secondary immune response?
the second exposure to the antigen
- antibodies are produced faster & at higher concentration
- B memory cells rapidly undergo mitosis to produce plasma cells which produce specific antibodies
what is humoral immunity?
a type of immune response that occurs when antigens are detected in the body
- involves T cells and other immune system cells they interact with e.g phagocytes
what are the four main stages of immune response?
encounter, activation, attack and memory
what is cell-mediated immunity?
a type of immune response that occurs when a cell is infected by a virus, bacteria or fungi and they detect antigen presenting cells
- involves B cells and production pf monoclonal antibodies
how are antigens used by the immune system?
they are used to identify pathogens, abnormal body cells, toxins, and cells from other individuals of the same species, e.g. organ transplants.
describe and explain how a secondary immune response differs to a primary immune response
- secondary immune response is faster and stronger than primary immune response
- this is because memory cells are produced during the primary response which are able to recognise the foreign antigen when its encountered again
