Diseases can be caused in humans in many a way. Some diseases may be pathogenic some may be caused by a lifestyle choice of an individual or an individual surrounding them, or some may be genetic.
Pathogens are micro-organisms which cause disease some bacteria, fungi and all viruses are pathogens. Pathogens enter our bodies through various methods such as breaks in the skin, the digestive system, and respiratory system. Pathogens can survive in many conditions such as in the air and in water and can be passed on in this way, examples such as; the common cold virus is airborne and cholera bacteria are waterborne. Pathogens can thrive in unhygienic conditions, rapidly multiply and can be picked up of surfaces such as a kitchen work surface. Pathogens enter our body produce toxins and damage cells. When a pathogen enters our body it may release a harmful molecule called a toxin which can damage cells or interfere with the bodily functions for example tetanus produces toxins which block the functioning of certain nerve cells causing muscle spasms. Other pathogens may damage cells physically this can be done in 3 ways; the cell may be ruptured and nutrients released into the cell; the organelles may be damaged by enzymes for example, the cell may be invaded by pathogens which then multiply causing lysis in cells this is common in virus’s. Pathogens may take nutrients from the cell and break them down for their own use this eventually starves the cell and kills it.
Diseases can be caused by the lifestyle choice of an individual or the individuals surrounding them. For example the increased risk of lung cancer caused by smoking or inhaling second hand smoke on a regular basis. While some people develop cancer without ever smoking, there is increased risk of developing lung cancer by smoking. Mutagenic agents in a cigarette can cause a mutation in the DNA of a cell causing it to rapidly multiply uncontrolled. Many other diseases such