I. The basic function of the digestive system is

Transcription

1 Chapter 15, Digestive System - ANATOMY OF THE DIGESTIVE SYSTEM I. The basic function of the digestive system is. This process is called. II. List 2 other names for the digestive tract: A. B. III. The digestive system consists of two parts: A. The, a hollow tube extending from the mouth to the anus that your food moves through. The alimentary canal is made up of several different parts that all play a unique role in the digestive process contains the teeth and tongue 2. - a common passageway for air and food that connects the mouth and the esophagus 3. - a muscular tube that propels food from the pharynx into the stomach a C-shaped organ located in the left upper part of the abdomen. Food enters the stomach through the sphincter and exits into the small intestine through the sphincter. Large folds called are formed when the empty stomach collapses inward. In the stomach, food is mixed with 1

2 digestive juices and churned into a thick paste called a muscular, tube-like structure that is the body s major digestive organ. The small intestine is suspended from the posterior body wall by a thin, fan-shaped structure called the. Blood vessels supplying the small intestine travel through the mesentery. The process of (breaking food into molecules the body can use), and (moving nutrients into the blood stream) are completed in the small intestine. The surface area of the small intestine is increased by finger-like folds of its inner lining (mucosa) called. The small intestine is divided into three parts: a. b. c this large, hollow tube absorbs water and delivers indigested food ( ) to the exterior of the body. The mucosa (inner lining) of the large intestine produces large amounts of mucus to lubricate the feces. The large intestines has the following subdivisions: a. b. (the appendix has no known digestive function) c. 2

3 d. e. B. The second part of the digestive system consists of the - These structures are important in the process of digestion, but are not a part of the alimentary canal. 1. glands secrete saliva into the mouth to lubricate food and to begin the process of digestion. a. Parotid glands - b. Submandibular glands - c. Sublingual glands chew food to break it into smaller piece. Two sets of teeth are formed: a. teeth, or baby teeth, are a set of teeth that begin to appear at 6 months of age and are usually lost by 12 years of age. 3

4 IV. b. teeth a set of teeth that have erupted by the end of adolescence (this includes the wisdom teeth which often fail to erupt) a soft, pink, triangular gland that secretes a large number of enzymes into the small intestinal tract. The pancreatic enzymes work to digest, and. The pancreas lies in the upper abdomen between the stomach and the small intestines. Pancreatic enzymes empty into the duodenum through the duct which shares a common opening with the bile duct this large organ occupies the upper portion of the abdomen and is located just under the diaphragm. It produces, a substance which is used to help digest fats a muscular sack that stores and concentrates bile when it is not needed. The gall bladder is located on the underside of the right lobe of the liver. The stomach, small intestines, colon, pancreas, liver and gall bladder are all located within the abdominal cavity. The abdominal cavity is lined by the parietal and the abdominal organs are covered by the. 4

5 Ch. 15, Digestive System - FUNCTIONS OF THE DIGESTIVE SYSTEM I. First, some definitions: 1. - placing food into the mouth 2. - propelling food from one organ to the next. Examples are in the mouth and ( involuntary, alternating waves of contraction and relaxation of the muscles in the walls of a hollow organ) which is the major means of propelling food through the alimentary canal. a. During swallowing, the and raise up to close off the nasal passage while the larynx raises up so that the covers its opening and prevents food from entering the trachea. 3. digestion physically breaking food into smaller pieces 4. digestion the process in which food molecules are broken down into their chemical building blocks by enzymes. Chemical digestion takes place in the,, and transport of the molecules formed during digestion from the lumen of the intestinal tract into the blood or lymph. * Most absorption takes place in the. * II. Mechanical Digestion 1. Mouth 2. Stomach 5

6 III. Chemical Digestion 1. Mouth a. - begins the digestion of starch 2. Stomach a. - makes the stomach contents very acidic b. - begins the digestion of proteins hydrochloric acid is necessary to activate pepsinogen into the active enzyme pepsin 3. Small intestine a. Pancreatic enzymes 1. pancreatic amylase - 2. trypsin - 3. chymotrypsin - 4. carboxypeptidase - 5. lipases - 6. nucleases - b. Enzymes of the Microvilli 1. peptidases - 2. sucrase - 3. maltase - 4. lactase - c. Bile - 4. Large intestine a. The large intestine produces no digestive enzymes, but that live within the colon metabolize some of the remaining nutrients, releasing about 500 ml of each day. 6

7 IV. Absorption of Nutrients 1. Stomach a. With the exception of and, virtually no absorption occurs in the stomach. 2. Small Intestine a. The absorption of nearly nutrients and some water occurs in the small intestine! 3. Large Intestine a. Absorption in the large intestines is limited to a few and most of the remaining. 7