Disease and Defence: How Your Body Fights Back

Pathogens are microorganisms that cause infectious diseases - think bacteria, viruses, fungi, and protists. They're everywhere and can spread through direct contact, water, or air, making you and plants seriously ill.

Your body has some clever non-specific defences that work like bouncers at a club. Your skin acts as a barrier, your nose traps pathogens in mucus and hairs, whilst your stomach's low pH kills most invaders before they cause trouble. Your trachea and bronchi use tiny hairs called cilia to sweep out unwanted guests.

When pathogens do get through, your immune system springs into action with white blood cells. These amazing cells can engulf and digest pathogens through phagocytosis, produce specific antibodies to target invaders, and even create memory cells that remember pathogens for faster responses next time.

Quick Tip: Remember that antibiotics only work against bacteria, not viruses - that's why you can't get antibiotics for a cold!

Bacterial diseases like salmonella food poisoning cause fever, cramps, and diarrhea through toxins, whilst gonorrhea spreads through sexual contact and causes painful urination. Viral diseases include measles (fever and red rash), HIV (which can develop into AIDS), and TMV in plants. Fungal diseases like rose black spot affect plants, whilst protist diseases include malaria, spread by mosquito vectors.

Vaccinations work by introducing small amounts of dead or inactive pathogens to stimulate antibody production, giving you immunity without getting ill. Monoclonal antibodies are identical antibodies produced from cloned cells, used in pregnancy tests and treating diseases.