The mouth is the organ of the body which is used for eating. It is where the food is being ingested through the help of the teeth, tongue and mixture of saliva. The saliva on the other hand is the term used for the mucous like fluid secretions of the three salivary glands of the mouth. As exocrine glands, each set of salivary glands produces different types of secretion that is released into the mouth.
The parotid glands create watery saliva that supplies enzyme; the submandibular glands produce mucus and enzyme components; and the sublingual glands, the smallest, create a mucous type of saliva. A reflex mechanism controls these secretions.
Food in the mouth stimulates chemical and mechanical digestion. The chemical digestion occurs through the action of the saliva that not only moistens the food we chew but also contains amylase, an enzyme that begins the digestive process of starches.
Another digestive process that occurs in the mouth, the mechanical digestion, depends on the teeth. Teeth rhythmically tear and pulverize food. The enamel that covers teeth is the hardest substance in the body and therefore protects teeth from the harsh effects of chewing. The tongue assists with the mechanical digestion by guiding positions and then leading the pulverized food into the esophagus. Another function of the tongue is that of taste. More than 2000 taste buds are responsible for our sensations of sweet, bitter, sour and salty when tasting foods.
As toddlers, we have the highest number of taste buds and a higher degree of taste sensitivity, so blank foods are more appealing. The number of taste buds declines as we grow older, which explains why older adults have diminished taste sensitivity. Older adults may need to be encourage to avoid to use too much salt particularly if they have hypertension or cardiac disorders.
Our sense of smell works along with our taste buds sensations. These two combined senses actually account for the perception (and enjoyment) of the flavors of different foods. Our positive or negative response to specific foods based on our sensory perception affects our food choices.
Portions of the pulverized or masticated food get formed into the shape of the ball called a bolus. The tongue effortlessly forms the bolus, which is then swallowed and passed by the epiglottis into the esophagus within about 5 to 7 seconds. The epiglottis is a flax of tissue that closes over the trachea to prevent the bolus from entering the lungs.