Human saliva

Photomacrograph of a sample of human saliva. Saliva is a watery liquid produced in the salivary glands and secreted into the oral cavity. It is composed of approximately 99% water together with electrolytes, enzymes, immunoglobulins, other proteins, urea, ammonia and some sugars. On average a healthy person will produce 1-1.5 L of saliva a day. Saliva aids taste, protection, lubrication, dilution, cleaning, buffering, digestion and tissue repair, as well as having anti-bacterial and anti-fungal properties. Analysing saliva provides an increasingly useful secondary means of diagnosing illness and monitoring health. If saliva production is altered, for example loss of salivary gland function after head and neck radiotherapy, this can lead to dry mouth (xerostomia), a decline in dental/oral health and increased risk of tooth decay. Width of image is 1 cm.