B1C Fast Facts
- Any organism which causes disease is called a pathogen.
- Diseases which can spread from one person to another is described as infectious.
- Hydrochloric acid in the stomach kills pathogens in our food.
- An animal which carries an organism that causes disease is known as a vector, e.g. a mosquito.
- Cancer is caused by cells which have lost the ability to stop dividing.
- Antibiotics are drugs that kill bacteria
B1C Fast Facts
- Antigens are protein molecules found on the surface of cells.
- A placebo is an inactive substance containing no medication and is used as a control when testing new drugs
Recall how pathogens cause the symptoms of a disea
Pathogens are microorganisms that cause disease. There are four types:
The symptoms of an infectious disease are caused by cell damage or by toxins produced by the pathogen.
Explain why each pathogen needs specific antibodie
- Every pathogen has unique molecules on the surface of its cells. These molecules are called antigens.
- When white blood cells come across a foreign antigen they'll start to produce proteins called antibodies, which lock on to and kill the new invading cells. The antibodies produced are specific to that pathogen so they will not lock on to other pathogens.
- Some white blood cells stay around in the blood after the pathogen has been fought off, these are called memory cells. If the person is infected with the same pathogen again these cells will remember it immediately make antibodies to kill it. The person is then naturally immune to that pathogen.
Explain the difference between active and passive
- Active immunity is where the immune system makes its own antibodies after being stimulated by a pathogen.
- Passive immunity is where you use antibodies made by another organism e.g. antibodies are passed from mother to baby through breast milk.
Explain the process of immunisation
1) Immunisation involves injecting dead/inactive pathogens into the body. These carry antigens, so even though they're harmless they still trigger an immune response where the white blood cells produce antibodies to attack them.
2) Some of these white blood cells will remain in the blood as memory cells so if live pathogens or the same type ever appear, the antibodies to kill them will produce immediately.
Explain the benefits and risks of immunisation
- Stops you from getting ill.
- If most people are immunised the disease won't be able to spread as easily.
- There can be some short term effects e.g. swelling, redness and feeling ill.
- Some people think that immunisation can cause other disorders
Explain how new treatments are tested
1) The drugs are tested using computer models and human cells grown in a laboratory.
2) Drugs that pass the first stage are tested on animals.
3) Drugs that have passed the animal tests are used in clinical trials.
Explain why blind trials are used in testing new d
The placebo effect is when the patient expects the treatment to work and so feels better, even though the treatment isn't doing anything.
Double blind trials aim to minimise the placebo effect so some patients are given the drug whilst others are given the placebo.
A placebo is designed to appear exactly the same as the drug itself but does not contain any of the drug.
The doctors and patients are not told who received the drug and who received the placebo drug until the trials are over.