The Immune System & Immunisation Flashcards
What do white blood cells do? ( & B-lymphocytes)
Travel around in your blood looking for microbes. If they are B-lymphocytes (memory lymphocytes) then they will respond by producing antibodies If they come across an invading microorganism.
What do microorganisms do as soon they enter the body?
Reproduce rapidly unless they’re destroyed.
What does every pathogen have on the surface of it’s cells?
Unique molecules called Antigens.
What do B-lymphocytes do when they come across a foreign antigen?
They start to produce proteins called antibodies, which bind to and kill new invading cells. These are specific and won’t bind onto any other pathogens.
Recall the 6 steps from the CGP Guide about memory lymphocytes and immunity - what happens when a pathogen enters your body for the first time, and then what happens after a second exposure to the same pathogen.
1) When it first enters, the response is slow because there aren’t many B-lymphocytes that can make the antibody needed to lock on to the antigen.
2) Eventually the body will produce enough of the right antibody to overcome the infection. At this stage the person will be showing symptoms of the disease.
3) After being exposed to an antigen, the B-lymphocyte specialises into a memory lymphocyte which will remember the pathogen’s antigen for a long time.
4) The person is now immune - their system has the ability to respond quickly to a second infection.
5) If the pathogen enters the body again, the immune system will produce a quicker and stronger immune response as it has remembered the pathogen and will be able to release the antibodies quicker.
6) The secondary response often gets rid of the pathogen before you being to show any symptoms.
(Look at graph)
What does immunisation do?
Stops you from getting infections
What does immunisation involve?
It involves getting injected with dead or inactive microorganisms Into the body. They contain antigens - your body makes antibodies to attack them and then remembers how to fight the pathogen if it comes into contact again.
What did Edward Jenner do?
5 steps
1) He took bits of scab from a girl with cowpox.
2) Put them into a cut on the arm of a boy.
3) The boy was a bit unwell but the recovered.
4) The Jenner exposed the boy to smallpox.
5) The boy didn’t catch smallpox
Why don’t people with cowpox get smallpox?
The cowpox antigens trigger B-lymphocytes to produce antibodies.
And because smallpox has some of the same antigens as cowpox, the immune system produces antibodies which stop both diseases.
What are the pros of immunisation?
Give 2
1) Big out brakes of diseases (called epidemics) can be prevented if lots of people are immunised.
2) Some diseases (like smallpox) have been wiped out completely due to the immunisation program.
What are the cons of immunisation?
1) Immunisation doesn’t always work ( sometimes it doesn’t give you immunity)
2) You can sometimes have a bad reaction to a vaccine.
