Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.
The body's defence systems against microbial diseases
First line - prevention of entry due to physical and chemical barriers;
- Skin - generally dry - wounds healed after blood clots
- Nasal hairs - trap larger particles
- Cilia in the respiratory system act together with mucus to trap smaller particles e.g. bacteria and pass these into the digestive system for disposal by acids and enzymes.
- Lysozyme is an enzyme, found in many body fluids e.g. tears, that breaks down cell walls of many bacteria
Second line - non specific
- Phagocytes (white blood cells) detect and engulf any thing "foreign" to the body, e.g. invading bacteria, and digest them
- The inflammatory response due to increased blood flow causes swelling and heat and increases contact with white blood cells
Third line - specific immune system
Antibodies produced by lymphocytes (white blood cells) in response to antigens on the surface of cells of invading micro-organisms.