Our bodies are amazing structures that defend us against infections under normal circumstances. As you read this chapter you will learn about disease-causing microorganisms, how the body defends itself against infections, and ways that infections might occur. You also learn how, as a medical assistant, you can be instrumental in helping to break the cycle of infection by practicing asepsis in the office setting as well as by educating patients in the prevention of disease transmission. The chapter concentrates on OSHA's role in the health-care setting and introduces the Blood-borne Pathogens Standard; it also explains how these regulations apply to you.