The name of the ENZYME contained in the SALIVA, by which starchy materials are changed into sugar, and so prepared for absorption. It is identical to the AMYLASE of pancreatic juice. (See DIGESTION; PANCREAS.)
A protein that acts as a catalyst for the body’s metabolic processes. The body contains thousands of enzymes, with each cell producing several varieties. The ?rst enzyme was obtained in a reasonably pure state in 1926. Since then, several hundred enzymes have been obtained in pure crystalline form. They are present in the digestive ?uids and in many of the tissues, and are capable of producing in small amounts the transformation on a large scale of various compounds. Examples of enzymes are found in the PTYALIN of saliva and DIASTASE of pancreatic juice which split up starch into sugar; the PEPSIN of the gastric juice and the trypsin of pancreatic juice which break proteins into simpler molecules and eventually into the constituent amino acids; and the thrombin of the blood which causes coagulation.
The diagnosis of certain disorders can be helped by measuring the concentrations of various enzymes in the blood. After a heart attack (myocardial infarction – see HEART, DISEASES OF), raised levels of heart enzymes occur as a result of damage to the cells of the heart muscle. Some inherited diseases such as GALACTOSAEMIA and PHENYLKETONURIA are the result of de?ciencies of certain enzymes.
Enzymes can be a useful part of treatment for some disorders. STREPTOKINASE, for example, is used to treat THROMBOSIS; wound-dressings containing papain from the pawpaw fruit – this contains protein-digesting enzymes – assist in the healing process; and pancreatic enzymes can be of value to patients with malabsorption caused by disorders of the PANCREAS.... enzyme
The ?uid secreted by the SALIVARY GLANDS into the mouth. The ingestion of food stimulates saliva production. Saliva contains mucus and an ENZYME known as PTYALIN, which changes starch into dextrose and maltose (see DIGESTION); also many cells of di?erent types. About 750 millilitres are produced daily.
The principal function of saliva is to aid in the initial processes of digestion, and it is essential for the process of mastication (chewing), whereby food is reduced to an homogeneous mass before being swallowed. In addition, the ptyalin in the saliva initiates the digestion of starch in the food.
An excessive ?ow of saliva known as salivation occurs as the result of taking certain drugs. Salivation also occurs as the result of irritation in the mouth – as for instance, in the teething child – and from DYSPEPSIA. De?ciency of saliva is known as XEROSTOMIA.... saliva
The glands (see GLAND) situated near, and opening into, the cavity of the mouth, by which the SALIVA is manufactured. They include the parotid gland, placed in the deep space that lies between the ear and the angle of the jaw; the submandibular gland, lying beneath the horizontal part of the jaw-bone; and the sublingual gland, which lies beneath the tongue.
Each gland is made up of branching tubes closely packed together, and supported by strong connective tissue. These tubes are lined by large cells that secrete the saliva, and ducts transfer the saliva to openings in the mouth. The parotid gland secretes a clear ?uid containing the ENZYME, PTYALIN; in the sublingual gland they mainly produce mucus, whilst the submandibular gland contains cells of both types.... salivary glands
A substance belonging to that group of carbohydrate known as the amyloses. It is the form in which utilisable CARBOHYDRATE is stored in granules within the seeds and roots of many plants.
Starch is converted into sugar when treated with heat in presence of a dilute acid. It is changed largely into dextrin when exposed to a considerable degree of dry heat, as in toasting bread; and a similar change into dextrin and malt-sugar takes place under the action of various enzymes (see ENZYME) such as the PTYALIN of the SALIVA. Starch forms a chief constituent of the carbohydrate foods (see DIET); and in the process of digestion, the above-mentioned change takes place to prepare it for absorption. It is also slowly broken down in the process of cooking.
Starch is used as a constituent of dusting powders for application to chafed or irritable areas of the skin.... starch
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