Disease
Disease is defined as any condition which impairs normal body functions/has the potential to disrupt homeostatic mechanisms, except that directly resulting from physical injury. Diseases have specific causes, signs and symptoms.
Diseases can be:
Infectious – caused by organisms (pathogens) and can be transmitted from one individual to another
Non infectious – diseases caused by organisms which cannot be transmitted from one individual to another including genetic and lifestyle diseases e.g. asthma, lung cancer, cystic fibrosis
Diseases are caused by pathogens (disease causing agents) such as viruses, worms and bacteria.
Virus
Viruses are simple non living particles, composed of DNA or RNA enclosed in a protein coat, requiring a living host for reproduction. Each virus possesses a unique surface protein molecule, specifically for the protein molecules on the surface of the target cell. Viruses invade a host to reprogram the host cell's DNA and induce reproduction of the virus
Worms
Worms live in the intestines of animals, attaching to the intestinal walls with hooks and suckers. They are composed of many segments, each containing both female and male components (hermaphrodite) and reproduce asexually. Tape worms produce many eggs to ensure survival of their offspring. Tapeworms require two hosts, a primary host which carries out the adult stage of life and a secondary/intermediate host which only contain other stages of life.
Bacteria
Bacteria are unicellular prokaryotic organisms. Bacterium contain a cell wall, a single stranded circular chromosome and cytoplasm in which enzymes and stored food granules are contained. All bacteria possess ribosomes and some possess flagella and cilia for locomotion and a capsule to protect against disease and desiccation. Bacteria may be round (cocci), rod shaped (bacilli) and spiral shaped (spirochaetes).
Disease is defined as any condition which impairs normal body functions/has the potential to disrupt homeostatic mechanisms, except that directly resulting from physical injury. Diseases have specific causes, signs and symptoms.
Diseases can be:
Infectious – caused by organisms (pathogens) and can be transmitted from one individual to another
Non infectious – diseases caused by organisms which cannot be transmitted from one individual to another including genetic and lifestyle diseases e.g. asthma, lung cancer, cystic fibrosis
Diseases are caused by pathogens (disease causing agents) such as viruses, worms and bacteria.
Virus
Viruses are simple non living particles, composed of DNA or RNA enclosed in a protein coat, requiring a living host for reproduction. Each virus possesses a unique surface protein molecule, specifically for the protein molecules on the surface of the target cell. Viruses invade a host to reprogram the host cell's DNA and induce reproduction of the virus
Worms
Worms live in the intestines of animals, attaching to the intestinal walls with hooks and suckers. They are composed of many segments, each containing both female and male components (hermaphrodite) and reproduce asexually. Tape worms produce many eggs to ensure survival of their offspring. Tapeworms require two hosts, a primary host which carries out the adult stage of life and a secondary/intermediate host which only contain other stages of life.
Bacteria
Bacteria are unicellular prokaryotic organisms. Bacterium contain a cell wall, a single stranded circular chromosome and cytoplasm in which enzymes and stored food granules are contained. All bacteria possess ribosomes and some possess flagella and cilia for locomotion and a capsule to protect against disease and desiccation. Bacteria may be round (cocci), rod shaped (bacilli) and spiral shaped (spirochaetes).