Parts of digestive system and their functions pdf

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parts of digestive system and their functions pdf

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Digestive System

Human digestive system , system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract , or the series of structures and organs through which food and liquids pass during their processing into forms absorbable into the bloodstream.

The system also consists of the structures through which wastes pass in the process of elimination and other organs that contribute juices necessary for the digestive process. 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.

Human digestive system Article Media Additional Info. Article Contents. Table Of Contents. While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.

Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions to improve this article requires login. External Websites. Articles from Britannica Encyclopedias for elementary and high school students. William T. See Article History. The human digestive system as seen from the front.

Britannica Quiz. You may know that the human brain is composed of two halves, but what fraction of the human body is made up of blood? Test both halves of your mind in this human anatomy quiz. The abdominal organs are supported and protected by the bones of the pelvis and ribcage and are covered by the greater omentum, a fold of peritoneum that consists mainly of fat.

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The Structure and Function of the Digestive System

The gastrointestinal tract , GI tract , GIT , digestive tract , digestion tract , alimentary canal is the tract from the mouth to the anus which includes all the organs of the digestive system in humans and other animals. Food taken in through the mouth is digested to extract nutrients and absorb energy, and the waste expelled as feces. The mouth , esophagus , stomach and intestines are all part of the gastrointestinal tract. Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines. A tract is a collection of related anatomic structures or a series of connected body organs. All vertebrates and most invertebrates have a digestive tract.

The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion the tongue , salivary glands , pancreas , liver , and gallbladder. Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has three stages: the cephalic phase , the gastric phase , and the intestinal phase. The first stage, the cephalic phase of digestion, begins with gastric secretions in response to the sight and smell of food. This stage includes the mechanical breakdown of food by chewing , and the chemical breakdown by digestive enzymes, that takes place in the mouth. Saliva contains digestive enzymes called amylase , and lingual lipase , secreted by the salivary glands and serous glands on the tongue. The enzymes start to break down the food in the mouth.

This article — the fifth in a six-part series describes the physiology and functions of the large intestine, the last portion of the gastrointestinal tract, as well as common conditions of both the small and large intestine. In the large intestine — the final section of the gastrointestinal tract — absorption of water and electrolytes takes place and colonic bacteria complete the process of chemical digestion. The large intestine is also where faeces are formed from the remains of food and fluid combined with by-products of the body. Intestinal content is pushed back and forth by haustral contractions and antiperistaltic contractions, until faeces are finally pushed towards the anal canal by mass movements. This article, the fifth in a six-part series exploring the gastrointestinal tract, describes the anatomy and functions of the large intestine. Citation: Nigam Y et al Gastrointestinal tract 5: the anatomy and functions of the large intestine.

Gastrointestinal tract

The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food.

Your digestive system is uniquely constructed to do its job of turning your food into the nutrients and energy you need to survive. The main organs that make up the digestive system in order of their function are the mouth, esophagus, stomach, small intestine, large intestine, rectum and anus. Helping them along the way are the pancreas, gall bladder and liver. The mouth is the beginning of the digestive tract.

Human digestive system , system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract , or the series of structures and organs through which food and liquids pass during their processing into forms absorbable into the bloodstream. The system also consists of the structures through which wastes pass in the process of elimination and other organs that contribute juices necessary for the digestive process. 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.

Human digestive system

The digestive system is a group of organs working together to convert food into energy and basic nutrients to feed the entire body. Food passes through a long tube inside the body known as the alimentary canal or the gastrointestinal tract GI tract. The alimentary canal is made up of the oral cavity, pharynx, esophagus, stomach, small intestines, and large intestines.

Gastrointestinal tract

Human digestive system , system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract , or the series of structures and organs through which food and liquids pass during their processing into forms absorbable into the bloodstream. The system also consists of the structures through which wastes pass in the process of elimination and other organs that contribute juices necessary for the digestive process.

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several sections, each of which has a specialised function. Two other organs are closely involved in digestion, the liver and pancreas. They are attached to the.


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  • tract (mainly in the oral cavity and stomach) physically break Organs of the digestive system are divided into 2 main Other functions of the liver include. Ryan D. - 24.05.2021 at 21:11
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