immunity.

Question 1

what is the purpose of the immune system?

Answer 1

protects the body by attacking pathogens if they manage to enter the body

Question 2

what do phagocytes do?

Answer 2

surround any pathogens in the blood and engulf them
enzymes in the phagocyte break down the pathogen and destroy it.

Question 3

what do lymphocytes do?

Answer 3

produce antibodies that respond to specific antigens on the surface of pathogens

Question 4

steps of lymphocyte killing pathogens:

Answer 4

1. each pathogen has unique antigens on its surface
2. a lymphocyte with an antibody that fits the antigen is activated
3. this lymphocyte divided many times to produce clones of identical lymphocytes
4. some of the lymphocytes produce lots of antibodies which stick to the pathogen and destroy it, whilst others stay in the blood as memory lymphocytes ready to respond immediately if the same antigen returns

Question 5

antibodies are ______

Answer 5

specific - they can only destroy one kind of pathogen

Question 6

what is the secondary response?

Answer 6

memory lymphocytes are already present and can secrete specific antibodies immediately

Question 7

what is immunization?

Answer 7

when you give a person a vaccine to prevent them becoming ill from a disease

Question 8

how do vaccines work?

Answer 8

vaccines contains antigens from the pathogen, often in the form of dead or weakened pathogens
the persons lymphocytes produce antibodies against the pathogen, creating memory lymphocytes in the process
if the person becomes infected with the real pathogen, the memory lymphocytes will give a rapid secondary response to the pathogen, meaning the person is very like to become ill with the disease

Question 9

what pathogens are in vaccines?

Answer 9

inactive - cannot cause the disease in the person receiving the vaccine

Question 10

advantages of immunization:

Answer 10

immunity is produced without being ill
immunity lasts a long time
if most people are immune, then the people who are unvaccinated are less like go catch the disease also - herd immunity

Question 11

disadvantages of immunization:

Answer 11

some people get a mild reaction of swelling or soreness, or a mile form of the disease
very rarely, a person has a major harmful reaction

Question 12

why does immunization only protect against one particular disease?

Answer 12

each pathogen has a particular antigen,
the immune system produces antibodies that are exactly the right shape to fit on to these antigens
other pathogens have antigens of a different shape, so one kind of antibody cannot bind to a different kind of antigen