Micro-Organisms and Microbes - the Causes of Disease.

Bacteria: Bacteria are singe-cell micro-organisms that live in the soil, water organic material or the bodies of plants and animal including humans.

Fungi: Fungi are microscopic plant-like organisms, an example is yeast.

Virus: A virus is an organism that must infect another cell to survive and multiply and may well cause disease in humans. Bacteria and viruses may reproduce rapidly inside the body and may produce poisons(toxins), which make us fell ill. Viruses damage the cells in which they reproduce.

A microbe is a broad term describing any small living organism and includes bacteria, virus and fungi and diseases are more likely to occur if large numbers of microbes enter the body as a result of unhygienic conditions or contact with infected people. The body has several methods of defending itself against the entry of microbes:

• The skin acts as a barrier
• The breathing organs produce a sticky liquid mucus, which covers the lining of these organs and traps microbes.
• The blood produces clots that seal cuts.

Although we are continually exposed to many different kinds of micro-organisms in our environment, only certain ones are capable of causing infectious disease in human beings. Micro-organisms that cause infectious diseases are called pathogens. However the body has an effective defence mechanism which includes the skin, stomach acid and the immune system that work together to prevent infection by blocking the entry of pathogens or by killing them once they invade the body. A delicate balance exists between the body’s defences and pathogens. When the body’s defence system resists the attacks of pathogens, infectious disease is prevented. But when the pathogens overwhelm the defences or immune system, the result is infection.