Causes of Disease in Humans

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Causes of Disease in Humans Disease is a term used as a description of certain symptoms, either physical or mental or both. It is often referred to as a malfunction of the body or mind which has an adverse effect on good health. Diseases can be caused by many different things but it mainly comes down to three things: pathogens, lifestyle and genetics. The most common causes of disease are Pathogens. These are microorganisms including bacteria, fungi and viruses that are able to gain entry to a host, colonise the tissues of the host, resist the defences of a host and cause damage to the host tissues. Pathogens normally enter the body by penetrating one of the organism’s interfaces with the environment. These interfaces include the skin (if it is broken), the gas-exchange system and the digestive system. When a pathogen enters the body and colonises the host’s tissues the result is an infection, disease then occurs when the infection leads to recognisable symptoms. Pathogens cause disease in two main ways: by damaging host tissue or by producing toxins. An example of a toxin producing pathogen is the cholera bacterium known as Vibrio cholera. This bacterium enters the body by the ingestion of contaminated water or food. Most of the pathogens ingested are killed by the acidic conditions in the stomach however some may survive if the pH isn’t low enough. The bacteria that survive enter the small intestine where they propel themselves like a corkscrew through the mucus lining of the intestine wall using their flagella. They then begin to produce a toxic protein which has two parts. One part binds to specific carbohydrate receptors on the cell surface membrane of the epithelial cells found in the walls of the small intestine. The other part (the toxic part), causes the ion channels on the epithelial cells to open which means that the chloride ions usually contained

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