The Mouth

Oral Cavity Functions

The mouthThe opening of the digestive tract where food enters and mastication begins. or oral cavity is also known as the buccal cavity. It includes the buccinatorCheek muscle In your cheek wall; helps blow air and keep food between teeth. muscle, which is located along the cheeks. This muscle aids in blowing out the cheeks, as in playing a trumpet. The oral cavity is a small area, often mistaken for the larger opening of the mouth. The tongue muscle extends to the top, highlighting the oral cavity’s limited size.

The mouth serves several functions, including sensory analysis, mechanical digestion, lubrication, and the initiation of chemical digestion. Sensory analysis helps identify the characteristics of food (e.g., wetness, dryness, or toughness) and sends information to the brain, which prepares the stomach and the other organs involved.. Mechanical digestion is the process of breaking down food physically, not chemically with enzymesProteins that speed up chemical reactions in the body.. Mechanical digestion in the mouth involves tearing and cutting food using the teeth and tongue. Mastication is the process of chewing food.  You may recall that the big muscle in your cheeks that causes chewing is called the masseterMasseter Elevator Jaw closer Runs along the jaw; raises the mandible to close your mouth.. Saliva lubricates the food which is compacted into a ball called a bolusA rounded mass of food mixed with saliva that is ready for swallowing..  Saliva lubricates the bolus preventing dryness during swallowing.

Chemical Digestion

Chemical digestion is the breakdown of substances via enzymes, acidA substance that releases hydrogen ions (H⁺) in solution., or chemical agents.  This is different than mechanical digestion because we are tearing apart atomsThe smallest units of matter that retain the properties of an element. and moleculesGroups of atoms bonded together. here, not proteinsLarge molecules made of amino acids with various functions in the body. and fat. There are enzymes in saliva such as amylase that breaks down carbohydrates or lipase that breaks down fats.  These enzymes are accustomed to the pHA measure of hydrogen ion concentration in a solution. that is typical of saliva. This is about a 5 or 6 on the pH scale.  When these enzymes get swallowed with the bolus and enter into the stomach, they stop working.  The 1-2 pH of the stomach is not their preferred conditions.  There are other enzymes that take over in that low pH and they are discussed in another minilecture

Mucosa

The mouth is lined with stratified squamous epithelial cellsThe basic structural and functional units of life.. These cells are keratinized for waterproofing, similar to the epidermisThe outermost layer of the skin, made of stratified squamous epithelium. of the skinThe body’s largest organ, providing protection and regulation.. Eating can cause the loss of some cells due to abrasion. This is not an issue because the cells are stratified. This structure ensures layers of protection.  As with all epithelia, there is connective tissue beneath it. Here, it appears that this submucosa is between areolar loose connective and dense irregular connective tissues.

The Palate

The palate separates the oral and nasalTwo small rectangular bones forming the bridge of the nose. cavities, preventing food from entering the nasal cavityThe internal space behind the nose that filters, warms, and humidifies incoming air. during eating.  The palate is an extension of the maxillaUpper jaw bones; form upper teeth sockets, hard palate front, and parts of the nose and orbit., the upper jaw bone, and a flap of keratinized tissues.  Cleft palates occur when the palate, hard or soft, is incomplete. It allows food exchange from the oral into the nasal cavity.  Sometimes cleft palates can take multiple surgeries to complete.