Paper 1 Specification 9 Flashcards
how do physical barriers such as hairs and mucus protect against pathogens
hairs and mucus in your nose trap particles that could contain pathogens
how do physical barriers like cells protect against pathogens
cells in your trachea and bronchi produce mucus that traps the pathogen. Other cells like the cilia move mucus up the throat so it can be swallowed again
how do chemical barriers such as the stomach and the eyes protect against pathogens
the stomach produces hydrochloric acid which kills most pathogens that are swallowed
the eyes produce a chemical called lysozyme in tears which kills bacteria on the surface
how does your immune system attack pathogens
-every pathogen has a unique antigen
-When a B lymphocyte finds an antigen it produces an antibody that binds to the pathogen so it can be found and destroyed by other white blood cells.
-antibodies produced are specific to that pathogen
-antibodies are then made rapidly and flow all around the body to find similar pathogens
how do memory lymphocytes give immunity to later infection
-when pathogens enter, there aren’t many lymphocytes that make the antibodies needed making the response slow
-memory lymphocytes stay in the body for a long time and remember specific antigens
-the person can respond to their second infection quickly. If it enters again there are more lymphocytes that recognise it.
-the response gets rid of the pathogen before you feel symptoms
how can you become immunised and how does it stop you from getting infections?
injecting inactive pathogens into the body. they are antigenic so even though they are harmless your body still makes antibodies
-also trigger memory lymphocytes so if live pathogens of the same type enter again the memory lymphocytes can cause a fast secondary immune response
why are antibiotics used to treat bacterial infections
can only be used to treat bacterial infections as they inhibit cell processes in the bacterium but not the host organism
how do scientists develop antibiotics nowadays?
use their knowledge of how the disease works to identify molecules that could be used as drugs to eliminate disease
what are the stages of pre-clinical testing
-tested on human cells first. (cannot test drugs that affect the whole body’s systems on cells)
-test drugs on live animals to find how toxic it is and to find the best dosage
what is clinical testing
-tested on healthy human volunteers
-sent to sick people where the optimum dose is found
-patients are randomly put into groups where one is given the new drug and one is a given placebo
-sent to a medical agency to be approved
