vaccination Flashcards
what are the two types of immunity?
active and passive
give examples of when HIV can spread from one infected person to another.
- during sexual intercourse
- when an intravenous drug user shares needles
- across the placenta of an infected mother
what is a vaccination?
an injection of antigens from a micro-organism that stimulates the formation of memory cells
how does HIV enter the cell?
- attachment proteins attach to receptors on T cells.
- RNA enters the cell.
- RNA is converted to DNA using reverse transcriptase.
- viral protein is produced.
- virus particles are assembled and released from the cell.
why aren’t antibiotics effective against viruses?
they’re not living and have no cell wall.
why is a low level of T helper cells so bad?
will have a poor immune system as there are fewer B cells so fewer antibodies
what could we do to treat HIV?
anti retro viral drug - this prevents virus replication
how do vaccinations prevent a person from developing certain diseases?
the vaccine produces a primary response so memory cells are made, which means when the person encounters the real pathogen antibodies are made quickly before symptoms can occur - body is immune to this pathogen
describe how antigen variability effects disease and disease prevention
antigen variability means the antigens on the surface are changing all the time so each time you’re infected by a new antigen you wont have immune cells with complementary receptors - this means you wont get a rapid response to a new infection
explain how vaccines provide protection to individuals against disease.
- specific B lymphocyte with complementary receptor binds to the antigen.
- specific T helper cell binds to antigen presenting cell and stimulates B cells.
- B lymphocyte divides by mitosis to form clones.
- on secondary exposure to antigen B memory cells divide by mitosis to produce B plasma cells which release antibodies faster at higher concentration.
explain how vaccines provide protections for populations against disease.
herd immunity - large number of population is vaccinated to reduce the spread of pathogens.
this means more people are immune and so unvaccinated people are less likely to come in contact with someone with disease.
explain the effect of antigen variability on disease and disease prevention.
antigens on the pathogens change shape due to gene mutations, so no long immune and B memory cell receptors cannot recognise the changes antigen on the secondary exposure.
explain how HIV causes the symptoms of AIDS.
- HIV infects and kills T helper cells, meaning they cant stimulate cytotoxic T cells, B cells and phagocytes, so B plasma cells cant release as many antibodies for agglutination and destruction of pathogens.
- immune system deteriorates so its more susceptible to infections.
