SB5j Immunuty Flashcards
antigens?
proteins in viruses and cell surface membrane
what do antigens allow?
allow the body to compare our own body cells to foreign invaders (immigrants)
antbodies?
molecules on the surface of lymphocytes that stop the pathogen from working and activates the lymphocyte to divide rapidly
how do antibodies stop a pathogen from working?
by matching the shape of the antigen on the surface of the pathogen
how do antibodies kill the pathogen?
they attach to pathogens with matching antigens
what happens to the pathogens in the secondary response?
~after the pathogens are killed some become memory lymphocytes and remain in the blood
what happens if you are infected again by the same pathogens?
the memory lymphocytes will recognise the antigens and stop you becoming ill - immune
how can immunity be triggered artificially?
vaccine
what do vaccines contain?
dead or weakened forms of a pathogen that include the antigens
how long can vaccines protect you from a disease?
many years
risks for vaccines? 4
~swelling and redness around the site of vaccination is common
~some children still get a mild form of the disease they are being vaccinated against
~very rarely, a child suffers an allergic reactions
~some people can become seriously ill during vaccination trials
advantages of vaccines? 3
~child can become immune to a disease without suffering from it
~the chances of long lasting harm are much less than if a person actually had a disease such as measles
~if enough children are vaccinated against a disease, then it becomes so rare that even unvaccinated individuals are unlikely to get it
herd immunity?
entire population being immune to a disease
Explain why vaccination against measles makes you immune to measles. (2 marks)
The vaccine introduces the measles antigen into the body. Lymphocytes respond by producing antibodies and some become memory cells. If the body is infected by measles again, a secondary response is triggered with more antibodies produced more quickly so we don’t become ill.
