Q.How does saliva act in body defence?

Step 1. The chapter lists lysozyme among the innate immune system's chemical mediators, describing it as an antibacterial agent that cleaves the bacterial cell wall.

Step 2. Saliva is one of the body-fluid sites (alongside tears, which the chapter's figure specifically calls out) where lysozyme is present and continuously active against bacteria entering the mouth.

Step 3. Beyond its chemical action, the constant secretion and swallowing of saliva physically washes microorganisms out of the oral cavity and down into the stomach, where the strongly acidic gastric secretions (also described in the chapter as a physiological barrier) go on to kill most ingested microbes. …

Connect saliva's lysozyme content and flushing action to the chapter's described chemical and …

• Overlooking lysozyme and only mentioning saliva's mechanical washing action …