Preventing, treating and curing disease

Microorganisms that cause disease are called pathogens- Pathogens may be bacteria, viruses, fungi and protists.

Communicable diseases are caused by pathogens. Sometimes they can be passed around through different species.

Pathogenic bacteria are the minority of bacteria but they have major effects on individuals and society's.

Bacteria divide rapidly (Binary Fission). They may produce toxins that affect your body and make you feel ill, they can directly damage your cells.

Viruses take over your bodies cells. They live and reproduce in the cells and they damage and destroy them.

Pathogens can be spread through the air; by contaminated food or water; through contact with other people or contaminated surfaces; and by animals theat draw blood, scratch or bite.

Ignaz Semmelweis - Dr in 1850's, noticed mothers died from childbed fever, concluded that it was because people were inspecting dead bodies then delivering babies, then concluded that there was an infectious agent involved, got medical students to wash hands, fewer deaths.

Louis Pasteur- germ theory- microorganisms cause disease

Joseph lister - antiseptic chemicals in theatres

Simple hygiene measures - Handwashing, Using disinfectants, Raw meat precautions and Coughing into a tissue.

Isolate infected individuals.

Destroy disease vectors- i.e the fleas that caused the Black Death.

Treatment or vaccination.

Measles- a virus spread by droplet infection from coughs and sneezes. It causes a fever and a rash and can sometimes be fatal. Currently there is no cure. Isolation of infected individuals and vaccination help to prevent spread.

HIV- initially causes flu like symptoms. Unless it is succsessfully treated with antiretroviral drugs the virus attacks the body's immune cells. Late stage HIV infection (Aids) occurs when a persons immune system becomes so badly damaged that it can no longer cope. It is spread by sexual contact, the exchange of bodily fluid, such as blood, which occurs when drug users share needles.

Salmonella- spread through bacteria ingested in undercooked food or on food prepared in unhygenic conditions. Salmonella are killed by cooking and pasteurisation. In the UK poultry are vaccinated against salmonella.

Gonorrhoea- STD transmitted by bacterium. Discharge from penis or vagina and pain on urination. Treatment by antibiotics however many strains are now resistant to antibiotics. Spread is controlled by antibiotics, condoms and limiting sexual partners.

Your skin acts as a barrier. If you cut it the barrier breaks but the body uses platelets to fix it. The clotting forms a scab which creates a seal and barrier, it also stops you from bleeding to death.

It produces antimicrobial secrestions to destroy pathogenic bacteria.

Healthy skin is covered with microorganisms that act as an extra barrier to the pathogens.

Respiratory and digestive systems:

Nose- is full of hairs and mucus that trap particles that may contain pathogens or irritate your lungs. Air pollution turns mucus black and this proves that the system is effective.

The trachea and bronchi secrete pathogen trapping mucus. Lining of the tubes covered in cilla, cilla beats to waft the mucus up to the back of the troat so it can be swallowed.

The stomach- produces hydrochloric acid that destroys the microorganisms in mucus when it is swallowed, it also destroys the pathogens you take in through food and drinks.

The immune system:

Phagocytosis- White blood cell ingests and digests the pathogen 

Producing antibodies- White blood cell produces specific chemicals to combat and destroy pathogen. Once antibodies have been produced once they can be produced again very quickly.

Producing antitoxins- White blood cell produces antitoxins to counteract the toxins produced by pathogens.

If a pathogen enters the body the immune system tries to destroy it.

Vaccination- introducing small amounts of a dead or inactive form of the pathogen to the body to stimulate the white blood cells to produce antibodies. If the same live pathogen re-enters the body antibodies are rapidly produced and this prevents infection.

Herd immunity- If a large portion of the population is vaccinated and immune against a pathogen the spread of it is much reduced.

Many useful materials, including all medicines, are specific mixtures of substances called formulations.

Painkillers and other medicines treat the symptoms of the disease but not the pathogens that cause it.

Antibiotics cure bacterial diseases by killing the bacterial pathogens inside your body.

The use of antibiotics has greatly reduced deaths from infectious diseases.

The emergence of strains of bacteria resistant to antibiotics is a matter of great concern.

Antibiotics cannot kill viral pathogens.

When new medicines are developed they are extensively tested for:

. Efficacy, toxicity and dosage.

New drugs are tested in laboritories using cells, tissues and animals.

They are tested in clinical trials on healthy volunteers and patients. Low doses used to test for safety and higher doses used for optimum dosage.

In double-blind trials, some patients are given a placebo and neither the Dr or patient knows whether they have it or not.

Peer review happens before publishing results to prevent false claims.

Genetic modification- changes the genetic material of an organism, it changes the code of life. Genes from one organism are removed and tranferred to the genetic material of another organism.

Gene editing allows scientists to remove, add or exchange genes relitatively simply and with great accuracy.

New medical products have been produced by genetically modifying bacteria. E.G Insulin genes removed from human and injected into plasmids that are then injected into bacterial cells.

Sheep and Goats have been genetically modified to produce chemicals needed to treat people in their milk.

Research is exploring the possibility of providing tissues and organs for human transplants from genetically modified animals.

Embryonic cells from human embryos and adult stem cells from adult bone marrow can be cloned and made to differentiate into many different types of cell.

Stem cells in bone marrow transplants has been well established. The stem cells provide a new supply of blood cells for the reciever.

Treatment with embryonic cells may be able to help people who are paralysed or people with conditions such as Type 1 diabetes.

Research is expensive and proving very difficult.

Most medical uses are still experimental.

Stem cells have some ethical and religious objections also there is still a lot of potential risks.