- Reading 1 Module Introduction
- Activity 1 Protection from Infection
- Reading 2 An Ounce of Prevention
- Activity 2 Stop That Disease
- Reading 3 On Guard
- Reading 3 Videos
- Activity 3 Defending
- Reading 4 Mimicking an Infection
- Reading 4 Discussion
- Additional Resources
On Guard: The Immune System
The purpose of this reading is to introduce students to the processes by which the immune system provides protection from viral and bacterial infections. Students read a short overview about the components of the immune system and how these components interact in their response to infection. Students then watch a video that clearly and concisely demonstrates this response.
In 1971 a baby boy was born and within 20 seconds after birth he was placed in a sterile plastic bubble where he was destined to live until his death at the age of 12. David Vetter was born with a rare disease called severe combined immunodeficiency (SCID) that occurs only in boys (see Figure 1). SCID patients lack components of their immune system that fight off infections by viruses, bacteria, and fungi. Left untreated, patients usually die before their first birthday from persistent infections.
The world around us, and we ourselves, teems with microbial life. Most of these microorganisms will not harm us but a small number can do serious damage if allowed to enter and grow in the human body. As evidenced by patients with SCID, it is the immune system that protects and defends against these pathogens.
The body’s cells have markers on their surface that identify the cells as part of that body or “self”. The immune system is a complex collection of specialized cells, proteins, tissues, and organs designed to seek out and destroy anything unrecognizable as “self”. This includes not only viruses and bacteria but also toxins, pollutants, pollen and any other foreign substances that are potentially harmful.