Health is a state of physical and mental well-being.
Communicable and non-communicable diseases are major causes of ill health.
Communicable diseases are caused by microorganisms called pathogens, which include bacteria, viruses, fungi and protists.
Muscles and the liver store extra glucose as glycogen, which can be converted back to glucose for use during exercise.
The heart rate increases during exercise to increase the blood flow to the muscles, which increases the supply for aerobic respiration, thereby increasing the rate at which CO<sub>2</sub> and lactic acid is removed.
Bacteria and viruses reproduce rapidly inside your body, bacteria can produce toxins to make you feel ill, viruses live and reproduce inside your cells, causing cell damage.
Pathogens can be spread by direct contact, by air or by water.
Bacteria multiply by simple cell division as often as every 20 minutes if they have enough nutrients and a suitable temperature.
The spread of disease can be prevented by simple hygiene such as washing your hands after using the toilet, by destroying vectors or by isolating infected individuals and by vaccination.
The first symptom of measles is often a fever, and after 3 days the patient develops a red skin rash.
The measles virus spreads in droplets when an infected person coughs or sneezes.
There is no cure for measles, isolation of patients and vaccination prevents spread.
The first symptom of HIV is often a flu-like illness.
Late stage HIV infection, or AIDS occurs when the body's immune system becomes so badly damaged that it can no longer deal with other infections or cancers.
HIV is spread by sexual contact or the exchange of body fluids, such as blood, which occurs when drug users share needles.
There is no treatment to a HIV infection, antiretroviral drugs can stop the virus from multiplying inside the patient so the virus does not damage the patient's immune system but the patient must take it for the rest of their life.
The bacteria that cause salmonella food poisoning are spread through undercooked food and poor hygiene.
Symptoms of salmonella include fever, abdominal cramp, diarrhoea and vomiting caused by the harmful toxins produced by the bacteria.
In the UK all chicken are vaccinated against salmonella, this controls the spread of the disease.
Gonorrhoea is a sexually transmitted disease.
Monoclonal antibodies are used in the treatment of diseases, they are produced from a single clone of cells and are specific to one binding site on one protein antigen.
If the drug is safe then the testing will continue on patients to find the optimal dose with the fewest side-effects.
New medical drugs are extensively tested for efficacy, toxicity and dosage.
The problem with extracting antibodies from a mouse is that a mouse will contain lots of different lymphocytes and lot of different antibodies, so to solve this problem we make monoclonal antibodies.
Antibiotics cure bacterial diseases by killing the bacterial pathogens inside your body.
If we inject a mouse with an antigen, then the lymphocytes will produce antibodies against the antigen.
If a large proportion of the population is immune to a pathogen, the spread of the pathogen is much reduced, this is called herd immunity.
Most new drugs are synthesised by chemists in the pharmaceutical industry, but the starting point may still be a chemical extracted from a plant.
Traditionally drugs were extracted from plants, for example, the plant foxglove was used to extract digitalis or the painkiller aspirin was extracted from willow trees.
In a double blind trial, neither the patients nor the doctors know which people are receiving the active drug and which are receiving the placebo.
In pregnancy testing, monoclonal antibodies are used to detect a specific hormone.
In the first stage of clinical testing, very low doses of the drug are given to healthy volunteers to check that the drug is safe for humans.
Due to the overuse of antibiotics, certain antibiotics are no longer effective against certain bacteria because the bacteria have evolved so that they are resistant to antibiotics.
Antibiotics do not destroy viruses because they reproduce inside the cells which is difficult to develop drugs that can destroy viruses without damaging your body cells.
If the same live pathogen enters the body, the white blood cells can produce the correct antibody.
A placebo is a tablet or injection with no active drug in it.
Painkillers and other medicines treat the symptons of the disease but do not kill the pathogen that cause it.
The use of antibiotics has greatly reduced deaths from infectious diseases.
Symptoms of gonorrhoea include a thick yellow discharge from the penis or vagina and it can also cause hurt when urinating.
Bacteria can release chemicals called toxin which are harmful to the body and make you feel unwell.