Mastication or chewing is the process by which food is mashed and crushed by teeth. It is the first step of digestion and it increases the surface area of foods to allow more efficient break down by enzymes. Digestion is the breaking down of chemicals in the body into a form that can be absorbed Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins During the mastication process, the food is positioned between the teeth for grinding by the cheek and tongue. Cheeks ( Latin: buccae) constitute the area of the Face below the Eyes and between the Nose and the left or right Ear The tongue is the large bundle of Skeletal muscles on the floor of the Mouth that manipulates Food for chewing and swallowing (deglutition As chewing continues, the food is made softer and warmer, and the enzymes in saliva begin to break down carbohydrates in the food. Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most After chewing, the food (now called a bolus) is swallowed. It enters the esophagus and continues on to the stomach, where the next step of digestion occurs.
Cattle and some other animals, called ruminants, chew food more than once to extract more nutrients. Cattle, colloquially referred to as cows, are domesticated Ungulates a member of the Subfamily Bovinae of the family Physiologically a ruminant is a Mammal of the order Artiodactyla that digests plant-based food by initially softening it within the animal's first stomach known After the first round of chewing, this food is called cud. CUD is an acronym sometimes used to describe the genetic disorder Primary carnitine deficiency.
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The chewing cycle
Mastication is a repetitive sequence of jaw opening and closing with a profile in the vertical plane called the chewing cycle. Mastication consists of a number of chewing cycles. The human chewing cycle consists of three phases
1. Opening phase: the mouth is opened and the mandible is depressed.
2. Closing phase: the mandible is raised towards the maxilla.
3. Occlusal or intercuspal phase: the mandible is stationary and the teeth from both upper and lower arches approximate.
Mastication motor program
Mastication is primarily an unconscious act, but can be mediated by higher conscious input. The motor program for mastication is an hypothesized central nervous system function by which the complex patterns governing mastication are created and controlled.
It is thought that feedback from proprioceptive nerves in teeth and the temporomandibular joints govern the creation of neural pathways, which in turn determine duration and force of individual muscle activation (and in some cases muscle fiber groups as in the masseter and temporalis). Proprioception (ˌproʊpriːəˈsɛpʃən PRO -pree-o-SEP-shun from Latin proprius, meaning "one's own" and perception is the Sense
The motor program continuously adapts to changes in food type or occlusion [1].
It is thought that conscious mediation is important in the limitation of parafunctional habits as most commonly, the motor program can be excessively engaged during periods of sleep and times of stress. A para-functional habit or parafunctional habit is the habitual exercise of a body part in a way that is other than the most common use of that body part It is also theorized that excessive input to the motor program from myofascial pain or occlusal imbalance can contribute to parafunctional habits. A para-functional habit or parafunctional habit is the habitual exercise of a body part in a way that is other than the most common use of that body part
In other animals
Chewing is largely an adaptation for mammalian herbivory. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands Herbivory is a form of Predation in which an Organism, known as a herbivore, consumes principally Autotrophs ref name=Campbell>Campbell Carnivores generally chew very little or swallow their food whole or in chunks, a fact to which many dog and cat owners can attest. A carnivore (ˈkɑrnɪvɔər meaning 'meat eater' ( Latin carne meaning 'flesh' and vorare meaning 'to devour' is any animal with a diet consisting The dog ( Canis lupus familiaris) is a domesticated Subspecies of the gray wolf, a Mammal of the Canidae family of the order WikipediaManual of Style (spelling, articles should conform to one overall spelling style of English typically the one most linked to the article topic (if it is geographic This act of gulping food without chewing has inspired the English idiom "wolfing it down". An idiom is a Phrase whose meaning cannot be deduced from the literal Definition, but refers instead to a figurative meaning that is known only
Ornithopods, a group of dinosaurs including the Hadrosaurids ("duck-bills"), developed teeth analogous to mammalian molars and incisors during the Cretaceous period; this advanced, cow-like dentition allowed the creatures to obtain more nutrients from the tough plant life. Ornithopods (ɔrˈnɪθoʊpɒd are a group of bird-hipped Dinosaurs that started out as small Bipedal running grazers and grew in size and Hadrosaurids or duck-billed Dinosaurs are members of the family Hadrosauridae, and include Ornithopods such as Edmontosaurus Molars are the rearmost and most complicated kind of Tooth in most Mammals In many mammals they grind food hence the Latin name mola, " Millstone Incisors (from Latin incidere, "to cut" are the first kind of Tooth in Heterodont Mammals They are located in the Premaxilla The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of This may have given them the advantage needed to usurp the formidable sauropods, who depended on gastroliths for grinding food, from their ecological niches. Sauropoda (sɔˈrɒpədə or the sauropods (/ˈsɔroʊpɒd/ are a suborder or infraorder of the Saurischian ("lizard-hipped" Gastroliths (' Stomach stones' or ' Gizzard stones' are rocks, which are or have been held inside the digestive tract of an animal They eventually became some of the most successful animals on the planet until the Cretaceous–Tertiary extinction event wiped them out. The Cretaceous–Tertiary extinction event, which occurred approximately ( Ma) was a large-scale mass extinction of animal and plant species in a geologically
In machinery
The process of mastication has, by analogy, been applied to machinery. The Zaca Fire is a Wildfire which began burning northeast of Buellton California, in Santa Barbara County, California. The U.S. Forest Service uses a machine called a masticator to "chew" through brush and timber in order to clear firelines in advance of a wildfire. A firebreak (also called a fireroad, fire line or fuel break) is a gap in Vegetation or other combustible material that acts as a barrier to [1]
Notes
- http://jn.physiology.org/cgi/content/full/92/2/773 - Influence of age on adaptability of human mastication.
External links
Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books Neuromuscular dentistry is a medical paradigm in which TM Joints masticatory muscles and central nervous system mechanisms follow generic physiologic and anatomicDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic