* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Digestive System (Human): Introduction
Document related concepts
Digestive System (Human): Introduction The digestive system comprises organs that break down and digest food, and remove unabsorbed wastes from the body. Its main feature is the alimentary canal, which measures about 30 ft (9 m) from mouth to anus and includes the esophagus, stomach, small and large intestines, and rectum. Also contributing to the digestive process are various accessory digestive organs: the teeth, tongue, salivary glands, liver, gallbladder, and pancreas. Mouth cavity Here the teeth, tongue, salivary glands, and other structures process food for swallowing. Esophagus This is the alimentary canal between the lower pharynx (throat) and the stomach. Swallowed food is moved through it by rhythmic muscular contractions known as peristalsis. Stomach This enlarged section of the alimentary canal churns, disinfects, and starts digesting food, producing chyme, a semifluid mixture. Sphincters These are rings of smooth muscle that contract to close an orifice. They include the pyloric sphincter (between the stomach and duodenum) and two anal sphincters. Digestive juices Saliva and juices secreted in the stomach, small intestine, and pancreas contain enzymes for digesting specific food substances. Small intestine This convoluted tube, about 21 ft (6.5 m) long, connects the stomach and the large intestine. It is subdivided into the duodenum, jejunum, and ileum. The small intestine is the part of the alimentary canal where most digestion occurs. Large intestine Also called the colon, this is a broad tube about 5 ft (1.5 m) long, extending from the ileum to the rectum. It is subdivided into the cecum (from which the appendix projects), and the ascending, transverse, descending, and sigmoid colons. Rectum This tube extends from the sigmoid colon and ends at a narrow orifice, the anus. Liver The body’s largest solid organ, the liver lies in the upper right part of the abdomen. Its complex chemical activities include secreting the emulsifying substance bile, and storing vitamins and glycogen (a carbohydrate produced from glucose). Gallbladder This sac stores bile, releasing it via the cystic duct and common bile duct into the duodenum. Pancreas This endocrine gland secretes insulin and pancreatic juice into the duodenum. © Diagram Visual Information Ltd.