Water and Germs (Lesson 5)

Introduction

1. What are germs?
2. Getting germs
3. Germ environment
4. Germ travel
5. Symptoms
6. Water's role
7. Water suppliers
8. Rules
9. Conclusion

Diseases & pathogens
Note on E. coli

Symptoms of infection?

How do pathogens cause diarrhea? Suppose you have picked up some pathogenic bacteria by touching a contaminated surface or object. You transfer the pathogens from your hands to your sandwich, and then you swallow them. The microbes now have an ideal environment in your intestines, and they reproduce rapidly. They also produce toxins that are very irritating to your intestines. These irritations have the unhappy effect of causing your intestines to lose water. This is diarrhea. Diarrhea often leaves other systems without enough water, a condition called dehydration. People who suffer from diarrhea are vulnerable to dehydration.

The role of antibodies

Our bodies are designed to fight off disease. Our immune systems can identify pathogens, then make antibodies to attack them. Once the body encounters and resists a pathogen, it "remembers" that event and can call upon those antibodies on short notice. We are then immune to that disease. When we get sick, it is usually because the pathogen is unfamiliar to our immune system and is present in such numbers that the body can't make antibodies quickly enough to prevent infection. Most vaccines prevent disease by introducing materials that trigger antibody formation.

See the kinds of
germs we're talking
about

Lesson 6 >