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Mouth |
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mouth, entrance to the digestive and respiratory tracts. The mouth, or oral cavity, is ordinarily a simple opening in lower animals; in vertebrates it is a more complex structure. In humans, the mouth is defined in front and at the sides by the lips, jawbone, teeth teeth, hard, calcified structures embedded in the bone of the jaws of vertebrates that perform the primary function of mastication. Humans and most other mammals have a temporary set of teeth, the deciduous, or milk, teeth; in humans, they usually erupt between the
..... Click the link for more information. , and gums; in the rear it merges with the throat. The roof of the mouth is composed of the hard and soft palates palate , roof of the mouth. The front part, known as the hard palate, formed by the upper maxillary bones and the palatine bones, separates the mouth from the nasal cavity. It is composed of a bone plate covered with a layer of mucous membrane tissue. ..... Click the link for more information. and the floor of the mouth is formed by the tongue tongue, muscular organ occupying the floor of the mouth in vertebrates. In some animals, such as lizards, anteaters, and frogs, it serves a food-gathering function. In humans, the tongue functions principally in chewing, swallowing, and speaking. ..... Click the link for more information. , a muscular structure that contains the organs of taste (taste buds). The lips, palates, tongue, and teeth are the major components in speech formation, using the "raw sound" formed in the larynx larynx , organ of voice in mammals. Commonly known as the voice box, the larynx is a tubular chamber about 2 in. (5 cm) high, consisting of walls of cartilage bound by ligaments and membranes, and moved by muscles. ..... Click the link for more information. . The process of digestion begins in the mouth; the chewing and grinding action of the teeth reduces the food to a readily digestible substance. The enzymatic process of converting starch to sugar is initiated by salivary amylase (ptyalin) excreted by the three salivary glands salivary glands , in humans, three pairs of glands that secrete the alkaline digestive fluid, saliva, into the mouth. Most animals have salivary glands that resemble those in humans; however, in some animals these glands perform other functions. ..... Click the link for more information. located at the angle of the jawbone and under the tongue. Saliva produced in these glands moistens food, preparing it for processing in the digestive system digestive system, in the animal kingdom, a group of organs functioning in digestion and assimilation of food and elimination of wastes. Virtually all animals have a digestive system. ..... Click the link for more information. . mouthor oral cavity or buccal cavityOrifice through which food and air enter the body. It opens to the outside at the lips and empties into the throat at the rear and is bounded by the lips, cheeks, hard and soft palates, and glottis. Its chief structures are the teeth (see tooth), tongue, and palate. It is the site of chewing and speech formation. The mouth is lined by mucous membranes containing small glands that, along with the salivary glands, keep it moist and clear of food and other debris. mouth 1. the opening through which many animals take in food and issue vocal sounds 2. the system of organs surrounding this opening, including the lips, tongue, teeth, etc. 3. the visible part of the lips on the face 4. the point where a river issues into a sea or lake 5. the opening of a container, such as a jar 6. the opening of or place leading into a cave, tunnel, volcano, etc. 7. that part of the inner lip of a horse on which the bit acts, esp when specified as to sensitivity 8. Music the narrow slit in an organ pipe 9. the opening between the jaws of a vice or other gripping device mouth [mau̇th] (anatomy) The oral or buccal cavity and its related structures. (engineering acoustics) The end of a horn that has the larger cross-sectional area. (geography) The place where one body of water discharges into another. Also known as influx. The entrance or exit of a geomorphic feature, such as of a cave or valley. (mining engineering) The end of a shaft, adit, drift, entry, or tunnel emerging at the surface. The collar of a borehole. (science and technology) Something resembling a mouth, that is, a place where one thing enters another or an opening at the receiving end of a container or enclosure. Mouth the part of a river that empties into a sea, lake, or another river. In rivers that dry out in their lower course, the place where the river terminates is designated the mouth. Several types of mouth are distinguished. A simple mouth refers to the terminus of a river that does not divide into branches, such as the Tiber. Rivers may also terminate in deltas, as in the Nile; estuaries, as in the Thames; or limans, as in the Iuzhnyi Bug. A river may end in a discordant junction, which is characteristic of the tributaries of mountain rivers in which downcutting has been less intensive than in the principal river. If a river does not transport its waters to a sea, lake, or another river, it is sometimes said to terminate in a blind end. Most large rivers that empty into a sea or large lake contain bars at the mouth; farther upriver are deep reaches that provide the customary wintering places for fish, such as the fish preserve pools in the Volga delta. The hydrological regime of river mouths is characterized by a complex variation in flow velocities, caused by such factors as ebb and flow, surge, increased flow rate during high water (ocean and lake rivers), and ice jams formed by drifting ice. Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
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