Mouth and oral structures
Some nutrients are complex molecules for example vitamin B 12 which would be destroyed if they were broken down into their functional groups. Capybara, rabbits, hamsters and other related species do not have a complex digestive system as do, for example, ruminants. At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis , which is waves of muscular contractions that move along the stomach wall. Ruminants have a fore-stomach with four chambers. For example, the liver stores certain vitamins and a type of sugar your body uses for energy.
The Digestive and Endocrine System Game
But also at the back of your throat is your windpipe, which allows air to come in and out of your body. When you swallow a small ball of mushed-up food or liquids, a special flap called the epiglottis say: If you've ever drunk something too fast, started to cough, and heard someone say that your drink "went down the wrong way," the person meant that it went down your windpipe by mistake.
This happens when the epiglottis doesn't have enough time to flop down, and you cough involuntarily without thinking about it to clear your windpipe. Once food has entered the esophagus, it doesn't just drop right into your stomach. Instead, muscles in the walls of the esophagus move in a wavy way to slowly squeeze the food through the esophagus. This takes about 2 or 3 seconds. Your stomach, which is attached to the end of the esophagus, is a stretchy sack shaped like the letter J.
It has three important jobs:. The stomach is like a mixer, churning and mashing together all the small balls of food that came down the esophagus into smaller and smaller pieces.
It does this with help from the strong muscles in the walls of the stomach and gastric say: GAS-trik juices that also come from the stomach's walls. In addition to breaking down food, gastric juices also help kill bacteria that might be in the eaten food.
The small intestine say: If you stretched out an adult's small intestine, it would be about 22 feet long 6. The small intestine breaks down the food mixture even more so your body can absorb all the vitamins, minerals, proteins, carbohydrates , and fats. PAN-kree-uss , liver, and gallbladder. Those organs send different juices to the first part of the small intestine. These juices help to digest food and allow the body to absorb nutrients.
The pancreas makes juices that help the body digest fats and protein. A juice from the liver called bile helps to absorb fats into the bloodstream. And the gallbladder serves as a warehouse for bile, storing it until the body needs it. Your food may spend as long as 4 hours in the small intestine and will become a very thin, watery mixture.
It's time well spent because, at the end of the journey, the nutrients from your pizza, orange, and milk can pass from the intestine into the blood. Once in the blood, your body is closer to benefiting from the complex carbohydrates in the pizza crust, the vitamin C in your orange, the protein in the chicken, and the calcium in your milk. Next stop for these nutrients: And the leftover waste — parts of the food that your body can't use — goes on to the large intestine.
The nutrient-rich blood comes directly to the liver for processing. The liver filters out harmful substances or wastes, turning some of the waste into more bile. The liver even helps figure out how many nutrients will go to the rest of the body, and how many will stay behind in storage. For example, the liver stores certain vitamins and a type of sugar your body uses for energy. At 3 or 4 inches around about 7 to 10 centimeters , the large intestine is fatter than the small intestine and it's almost the last stop on the digestive tract.
Like the small intestine, it is packed into the body, and would measure 5 feet about 1. The large intestine has a tiny tube with a closed end coming off it called the appendix say: It's part of the digestive tract, but it doesn't seem to do anything, though it can cause big problems because it sometimes gets infected and needs to be removed. Like we mentioned, after most of the nutrients are removed from the food mixture there is waste left over — stuff your body can't use.
A number of alterations, often causing more or less distress, occur in the physical condition and functions of the gastrointestinal tract during pregnancy. The digestive tract begins at the lips and ends at the anus. It consists of the mouth , or oral cavity, with its teeth , for grinding the food, and its tongue, which serves to knead food and mix it with saliva ; the throat, or pharynx ; the esophagus ; the stomach ; the small intestine , consisting of the duodenum , the jejunum, and the ileum ; and the large intestine , consisting of the cecum , a closed-end sac connecting with the ileum, the ascending colon, the transverse colon, the descending colon, and the sigmoid colon , which terminates in the rectum.
Glands contributing digestive juices include the salivary glands , the gastric glands in the stomach lining, the pancreas , and the liver and its adjuncts—the gallbladder and bile ducts. All of these organs and glands contribute to the physical and chemical breaking down of ingested food and to the eventual elimination of nondigestible wastes. Their structures and functions are described step by step in this section. Little digestion of food actually takes place in the mouth. However, through the process of mastication , or chewing, food is prepared in the mouth for transport through the upper digestive tract into the stomach and small intestine, where the principal digestive processes take place.
Chewing is the first mechanical process to which food is subjected. Movements of the lower jaw in chewing are brought about by the muscles of mastication the masseter, the temporal, the medial and lateral pterygoids, and the buccinator. The sensitivity of the periodontal membrane that surrounds and supports the teeth, rather than the power of the muscles of mastication, determines the force of the bite.
Mastication is not essential for adequate digestion. Chewing does aid digestion, however, by reducing food to small particles and mixing it with the saliva secreted by the salivary glands. The saliva lubricates and moistens dry food, while chewing distributes the saliva throughout the food mass. The movement of the tongue against the hard palate and the cheeks helps to form a rounded mass, or bolus , of food.
The lips, two fleshy folds that surround the mouth, are composed externally of skin and internally of mucous membrane , or mucosa.
The mucosa is rich in mucus-secreting glands, which together with saliva ensure adequate lubrication for the purposes of speech and mastication. The cheeks, the sides of the mouth, are continuous with the lips and have a similar structure. A distinct fat pad is found in the subcutaneous tissue the tissue beneath the skin of the cheek; this pad is especially large in infants and is known as the sucking pad.
On the inner surface of each cheek, opposite the second upper molar tooth, is a slight elevation that marks the opening of the parotid duct, leading from the parotid salivary gland , which is located in front of the ear. Just behind this gland are four to five mucus-secreting glands, the ducts of which open opposite the last molar tooth. The roof of the mouth is concave and is formed by the hard and soft palate. The hard palate is formed by the horizontal portions of the two palatine bones and the palatine portions of the maxillae, or upper jaws.
The hard palate is covered by a thick, somewhat pale mucous membrane that is continuous with that of the gums and is bound to the upper jaw and palate bones by firm fibrous tissue.
The soft palate is continuous with the hard palate in front. Posteriorly it is continuous with the mucous membrane covering the floor of the nasal cavity. The soft palate is composed of a strong, thin, fibrous sheet, the palatine aponeurosis, and the glossopalatine and pharyngopalatine muscles. A small projection called the uvula hangs free from the posterior of the soft palate. The floor of the mouth can be seen only when the tongue is raised. In the midline is a prominent, elevated fold of mucous membrane frenulum linguae that binds each lip to the gums, and on each side of this is a slight fold called a sublingual papilla , from which the ducts of the submandibular salivary glands open.
Running outward and backward from each sublingual papilla is a ridge the plica sublingualis that marks the upper edge of the sublingual under the tongue salivary gland and onto which most of the ducts of that gland open.
The gums consist of mucous membranes connected by thick fibrous tissue to the membrane surrounding the bones of the jaw. The gum membrane rises to form a collar around the base of the crown exposed portion of each tooth. Rich in blood vessels, the gum tissues receive branches from the alveolar arteries; these vessels, called alveolar because of their relationship to the alveoli dentales, or tooth sockets, also supply the teeth and the spongy bone of the upper and lower jaws, in which the teeth are lodged.
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