1. What is an infection, and what causes it......?

1. What is an infection, and what causes it?

2. By what ways are diseases spread from one person to another?

3. How does the skin function as a defense against disease? Wut about thee digestive system?

4. Explain how immunization aids in the defense against disease.

5. Distinguish between active and passive immunity.

It sounds like you are asking questions from a worksheet or exam for a basic infectious disease class! Well, here goes:

1. Everyone has bacteria present in their body at all times. Presence of bacteria is called colonization. When the bacteria invades tissues and causes illness, that is an infection.

2. Diseases are spread through three modes of transmission: airborne, direct contact, and indirect contact. By far the most common mode of transmission is direct contact, through hand to hand transmission.

3. Skin acts as a physical barrier against disease. Remember that your skin is commonly colonized with bacteria. But if your skin is broken, by either cuts or scrapes, the bacteria can reach tissues not meant to receive bacteria.

4. Immunization introduces a weakened or dead agent (usually virus) to your immune system and "teaches" your body how to respond to that agent for the next time.

5. Immunity is when your immune system has learned how to defeat an agent introduced to your body so that you no longer will develop illness from an agent. Active immunity is when you develop antibodies (the part of your immune system that can fight a particular agent) as a result of being exposed to the disease. Passive is when you are injected with anitbodies to fight the disease. Passive immunity is a short term immunity.

Good luck in your class!