1.1 Pathogens

1.1 Pathogens

Micro-organisms that cause disease, e.g.viruses and bacteria
1. A microorganism is a single celled organism too small to be seen without a microscope
2. Disease is a description of certain symptoms - physical or mental. It suggests a malfunction of body or mind which has an adverse affect on good health
3. For a microorganism to be considered a pathogen it must:
  1. gain entry to the host
  2. colonise the tissues of the host
  3. resist the defences of the host
  4. cause damage to the host tissues
How pathogens enter the body:
1. the gas exchange system
2. The digestive system
The Body's defences against pathogens:
1. mucous layer that covers exchange surfaces and forms a sticky, hard to penetrate barrier
2. the production of enzymes that break down pathogens
3. production of stomach acid that kills microorganisms
How pathogens cause disease
1. By damaging host tissues
2. by producing toxins

Resource summary

	Created by Georgia Knight almost 10 years ago