Glencoe Health Lesson 3 The Digestive System

LESSON 3 The Digestive System The digestive system provides nutrients and energy for your body through the digestion of food. BIG IDEA New Vocabulary bile mastication peristalsis peptic ulcer The digestive system consists of one long tube and the organs that attach to it.  The organs produce digestive chemicals (enzymes and acids) that break down the nutrients into simpler forms so that absorption through the intestinal wall and into the blood stream can occur. What is the function of the digestive system? To change ingested food into a form that can be used by the cells, to get the nutrients into the blood stream, to reabsorb water, and to eliminate wastes. gastric juices appendicitis Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

What Happens During Digestion LESSON 3 The Digestive System What Happens During Digestion Main Idea In digestion, foods are broken down and absorbed as nourishment or eliminated as waste. The foods you eat must be broken down into nutrients to be absorbed into the blood and carried to the body’s cells. The foods you eat provide nourishment. That food and drink, however, must be broken down into smaller nutrients to be absorbed into the blood and carried to the body’s cells. The digestive system functions can be divided into 3 main processes…What are they? Digestion, Absorption and Elimination (NEXT SLIDE) Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

Three Main Processes of the Digestive System LESSON 3 The Digestive System What Happens During Digestion Three Main Processes of the Digestive System Digestion The mechanical and chemical breakdown of foods within the stomach and intestines for use by the body’s cells. Absorption The passage of digested food from the digestive tract into the cardiovascular system. Elimination The body’s expulsion of undigested food or body wastes. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System How Digestion Works Main Idea The digestive system consists of the mouth, esophagus, stomach, and intestines. Carbohydrates begin digesting in the mouth, protein begins digesting in the stomach, and fats begin digesting in the small intestines. Carbohydrates: digestion begins in the mouth, where salvia breaks down starch molecules. In the small intestine, the Pancreatic Amylase and Maltase enzymes break down those molecules into glucose, which is absorbed into the blood. Protein: digestion begins with acid in the stomach and is completed in the small intestine, where proteins are broken down into amino acids that are absorbed by the blood. Fat: digestion occurs mainly in the small intestine, where bile acids from the liver dissolve fats and move the smaller molecules into the lining of the small intestine. Digestion includes two processes…Mechanical and Chemical (NEXT SLIDE) Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

How Digestion Works Digestion includes two processes: LESSON 3 The Digestive System How Digestion Works Digestion includes two processes: Mechanical Processes Chewing, mashing, and breaking food down. Chemical Processes Secretions produced by digestive organs. Mechanical Processes involves chewing, mashing and breaking down food. This process begins in the mouth as the food is chewed. Chemical Processes involves secretions produced by digestive organs. Chemical digestion involves breaking down the food into simpler nutrients that can be used by the cells. Chemical digestion begins in the mouth when food mixes with saliva. Saliva contains an enzyme (amylase) that begins the breakdown of carbohydrates. What is an enzyme?? (An enzyme is a protein that can catalyze certain biochemical reactions). Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System How Digestion Works The teeth break the food you eat into smaller pieces. Mastication prepares food to be swallowed. New Vocabulary Food is chewed into smaller pieces.  Adults have 32 specialized teeth—teeth that can grind, chew, and tear different kinds of food. The tongue is an organ consisting of skeletal muscles (voluntary muscles) that move the food around the mouth to allow for efficient mechanical digestion. Salivary glands beneath and in back of the tongue secrete the saliva that allows for easier swallowing of food and the beginning of chemical digestion.  What does the mouth do?—houses teeth, salivary glands and tongue for mechanical and chemical digestion    Teeth—chews, grinds, and tears food into smaller pieces  mastication The process of chewing. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System How Digestion Works Salivary glands produce saliva, which contains an enzyme—Salivary Amylase—that begins to break down the starches and sugars in food into smaller particles. The tongue prepares chewed food for swallowing by shaping it. These glands produce digestive juices. Saliva contains an enzyme Salivary Amylase that begins to break down the starches and sugars in food into smaller particles. The tongue prepares the chewed food for swallowing by shaping it. The UVULA, a small flap of tissue at the back of the mouth, prevents food from entering the nasal passages. The epiglottis, tissue covering the throat, prevents food from entering the respiratory system. From the mouth the process continues through the…Pharnyx Swallowing forces the chewed food through a tubular entrance (pharynx) to the esophagus (food tube).  As food is swallowed a flap-like valve, the epiglottis, closes over the trachea (windpipe) to prevent food entering the windpipe and causing choking.   Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System The Esophagus When food is swallowed, it moves through the esophagus, stomach, and intestines through peristalsis. sphincter muscle—circular muscle at the entrance of the stomach—allows food to move from the esophagus into the stomach. peristalsis A series of involuntary muscle contractions that moves food through the digestive tract. Esophagus The esophagus connects the pharynx with the stomach.  Contractions of the esophagus push the food through a sphincter (a ring of smooth muscle that closes off an opening in the body) and into the stomach.  NOTE:  The digestive system moves food along by way of peristalsis, a wavelike contraction of smooth (involuntary) muscle. The action of peristalsis begins as soon as food is swallowed. A sphincter muscle—circular muscle at the entrance of the stomach—allows food to move from the esophagus into the stomach. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

The Stomach The stomach has three tasks: LESSON 3 The Digestive System The Stomach The stomach has three tasks: Mixing foods with gastric juices Storing partially digested food and liquid Moving food into the small intestine The stomach is a hollow, sac-like organ enclosed in a wall of muscles. These muscles are flexible and allow the stomach to expand when you eat. The 3 tasks that the stomach has is to Mix foods with gastric juices. Gastric Juices are secretions from the stomach lining that contain hydrochloric acid and pepsin, an enzyme that digests protein. The hydrochloric acid kills bacteria taken in with food and creates an acidic environment for pepsin to do its work. Mucus produced by the stomach forms a protective lignin so that gastric juices do not harm the stomach. Storing partially digested food and liquid—The stomach holds the food for further digestion before it is moved into the small intestine. Moving food into the small intestine—as food is digested in the stomach, it is converted to Chyme—a creamy fluid mixture of food and gastric juices. Peristalsis moves, the chime into the small intestine through an opening controlled by another sphincter muscle. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System The Stomach The hydrochloric acid in gastric juices kills bacteria taken in while food and creates an acidic environment for pepsin to do its work. New Vocabulary gastric juices Secretions from the stomach lining that contain hydrochloric acid and pepsin, an enzyme that digests protein. The stomach starts chemical digestion of protein.  Secretions from the stomach lining consist of about two liters of hydrochloric acid (HCl), pepsin, and other fluids that make up gastric fluids each day. The fluid is extremely acidic and it helps kill bacteria and other pathogens that may have been ingested. The thick mucus also produced by the stomach lining usually keeps the acids from damaging the lining. If not enough mucus is produced or if too much acid is produced, peptic ulcers form.  Heredity, stress, smoking, and excessive alcohol intake can make the ulcers worse.  The condition can worsen and bleeding ulcers can result.  Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System The Stomach The stomach holds the food for further digestion before it is moved into the small intestine. As food is digested in the stomach, it is converted to chyme, a creamy, fluid mixture of food and gastric juices, which is moved into the small intestine. Food stays in the stomach for approximately 3-4 hours and moves through another sphincter muscle to pass into the small intestine. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System The Stomach The three layers of stomach muscles each move in different directions to aid both mechanical and chemical digestion. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

The Pancreas, Liver, and Gallbladder LESSON 3 The Digestive System The Pancreas, Liver, and Gallbladder The liver produces bile and the pancreas produces other enzymes that break down the carbohydrates, fats, and proteins in food in the small intestine. New Vocabulary bile A yellow-green, bitter fluid important in the breakdown and absorption of fats. In the small intestine, the juices of two other digestive organs mix with the food to continue the process of digestion. The pancreas has three important functions that help the digestive system change food into a form that can be used by the cells. 1)    It produces enzymes which help break down proteins, lipids, and carbohydrates. 2)    It produces the hormone, insulin, which helps regulate blood glucose levels. 3)    It produces sodium bicarbonate which helps to neutralize stomach acids. The liver is a large organ located just above the stomach.  The liver produces bile which helps digest lipids.  Bile is stored in the gallbladder and flows from the gallbladder to the duodenum where it helps digest fats. The gall bladder is a small, greenish organ located just under the liver.  It stores bile produced by the liver until it is secreted directly into the first section of the small intestine. At mealtimes, it is secreted from the gallbladder into the bile duct to reach the intestine and mix with fats in food. Bile acids dissolve the fats into the watery contents of the intestine. After the fat is dissolved, it is digested by enzymes from the pancreas and the lining of the intestine. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

The Small and Large Intestines LESSON 3 The Digestive System The Small and Large Intestines The small intestine is 20 to 23 feet in length and one inch in diameter. It consists of three parts: the duodenum, the jejunum, and the ileum. Small intestine The small intestine is folded and curled around a small area in the abdominal cavity. The small intestine has three distinct parts:  the duodenum, the jejunum, and the ileum.  Each day, about 9 liters of fluid enters the duodenum.  Most chemical digestion takes place in the duodenum by chemicals secreted by the liver, pancreas and small intestine. The other two sections of the small intestine, the jejunum and the ileum, absorb food molecules by way of the villi directly into the blood stream. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

The Small and Large Intestines LESSON 3 The Digestive System The Small and Large Intestines About 90 percent of all nutrients are absorbed through the small intestine. Unabsorbed material leaves the small intestine in the form of liquid and fiber and moves by peristalsis into the large intestine. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

The Small and Large Intestines LESSON 3 The Digestive System The Small and Large Intestines The inner wall of the small intestine contains millions of fingerlike projections called villi that are lined with capillaries that absorb the nutrients. The inside surfaces of the intestine are covered with projections called villi.  These finger-like structures are covered in smaller projections called microvilli and work to absorb food molecules that have been broken down by the processes of chemical digestion. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

The Small and Large Intestines LESSON 3 The Digestive System The Small and Large Intestines The undigested parts of the food – fiber, or roughage – pass into the colon, or large intestine. The large intestine is about 2.5 inches in diameter and 5 to 6 feet in length. Large Intestine—function is to absorb water, vitamins, and salts, from the undigested parts of the food and to eliminate waste. Receives the “left over” material from chemical digestion that is nutrient free. The large intestine receives the material “left-over” from chemical digestion that is basically nutrient free. Only water, cellulose, and indigestible materials are left. The main job of the large intestine is to remove water from the undigested material. Water is quickly removed from the material through villi and returns to the blood stream.   The last part of digestion is the … Rectum The last part of the digestive tract is the rectum, a “holding area” for the undigested material. Waste leaves the body from this area. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

Digestive System Problems LESSON 3 The Digestive System Digestive System Problems Main Idea Digestive problems range from indigestion to acute conditions that require immediate medical attention. Taking care of your digestive system begins with the foods you eat and how you eat them. What purpose is served by eating a variety of low-fat, high-fiber food? These food contribute to the proper functioning of the digestive system. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

Tips for Maintaining Digestive Health LESSON 3 The Digestive System Digestive System Problems Tips for Maintaining Digestive Health Eat a variety of low-fat, high-fiber foods. Wash your hands before preparing or eating meals. Eat slowly and chew your food thoroughly. To maintain your digestive health, eat a variety of low-fat, high-fiber foods, wash your hands before preparing or eating meals, eat slowly and chew your food thoroughly, drink at least eight 8 oz glasses of water a day, and avoid using food as a way of dealing with your emotions. Some digestive system problems may require medications and a visit to a health professional. Drink at least eight 8-ounce glasses of water a day. Avoid using food as a way of dealing with your emotions. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

Functional Problems Indigestion Constipation Heartburn Gas Nausea LESSON 3 The Digestive System Functional Problems Indigestion Discomfort in the abdomen, sometimes with gas and nausea. Constipation Feces become dry and hard, making bowel movements difficult. Heartburn A burning sensation in the chest that may rise up to the throat. Gas Cramps or an uncomfortable feeling of fullness in the abdomen. The functioning of the digestive system may be affected by illness, stress, or eating a particular food. Functional problems of the digestive system include some of the following… Indigestion—a feeling of discomfort in the upper abdomen, sometimes with gas and nausea. It can be caused by eating too much food, eating too quickly, eating spicy or high-fat foods, or having a stomach disorder or stress. Constipation—causes the feces to become dry and hard, making bowel movements difficult. It can be caused by not drinking enough water or not consuming enough fiber to move wastes through the digestive system. Heartburn—a burning sensation in the center of the chest that may rise up to the throat. It results from acid reflux, or the backflow of stomach acid into the esophagus. Using tobacco, alcohol and aspirin, or eating spicy or greasy foods can cause heartburn. Gas—produced from the breakdown of food is normal. Excessive gas can result in cramps or an uncomfortable feeling of fullness in the abdomen. Nausea—is the feeling of discomfort that sometimes precedes vomiting. Motion sickness, pathogens, some medications and dehydration can cause nausea. Diarrhea—is the frequent passage of watery feces. It can be caused by bacterial or viral infections, some medications, a change in eating style, overeating, emotional turmoil, or nutritional deficiencies. Dehydration may result with each episode of diarrhea. Nausea A feeling of discomfort that sometimes precedes vomiting. Diarrhea The frequent passage of watery feces. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

Structural Problems Tooth decay Gastritis Gallstones LESSON 3 The Digestive System Structural Problems Tooth decay Makes it difficult to chew foods thoroughly. Gastritis Inflammation of the mucous membrane that lines the stomach. Gallstones Blockage of the bile duct between the gallbladder and the small intestine. Lactose Intolerance Inability to digest lactose, a type of sugar found in milk and other dairy products. The seriousness of structural problems of the digestive system can vary. Some problems are temporary or easily treated, others are serious and require immediate medical attention. Gastritis—an increase in the production of stomach acid, use of tobacco, or alcohol, bacterial or viral infections, and some medications can cause this. Symptoms include pain, indigestion, decreased appetite, and nausea and vomiting. Peptic Ulcer—is a sore in the lining of the digestive tract. They can be casued by bacterial infections or the overuse of aspirin. Ulcers can casue stomach bleeding. Gallstones—form when cholesterol in bile crtystallizes. Gallstones can block the bile duct between the gallbladder and the small intestine. Symptoms include pain in the upper right portion of the abdomen, nausea, vomiting, and fever. Lactose Intolerance-Lactose is normally broken down by the enzyme lactase. People who are lactose intolerant do not produce enough lactase. Symptoms include abdominal cramps, bloating, gas, and diarrhea. Soy products are a good replacement for milk and dairy products. Appendicitis—is the inflammation of the appendix, the 3 to 4 inch tube at the tip of the large intestine. It can be caused by a blockage or bacterial infection. Symptoms include pain the lower right abdomen and a fever. Colitis—it may be caused by bacterial or viral infections. Colitis Inflammation of the large intestine, or colon. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

Structural Problems Colon Cancer Colon Cancer Hemorrhoids Hemorrhoids LESSON 3 The Digestive System Structural Problems Colon Cancer Colon Cancer Cancer that usually develops in the lowest part of the colon, near the rectum. Hemorrhoids Hemorrhoids Veins in the rectum and anus that may become swollen and inflamed. Veins in the rectum and anus that may become swollen and inflamed. Crohn’s Disease Crohn’s Disease Inflammation of the lining of the digestive tract. Inflammation of the lining of the digestive tract. Colon Cancer—is the second leading casue of cancer death in the United States. It usually develops int eh lower part of the colon, near the rectum. A low-fat, high-fiber eating plan decreased the risk of colon cancer. Any rectal bleeding should be checked by a medical professional immediately. Hemorrhoids-may occur with constipation, during pregnancy they are very common, and after childbirth. Itching, pain and bleeding. Crohn’s Disease—causes inflammation of the lining of the digestive tract. Symptoms include diarrhea, weight loss, fever, and abdominal pain. The cause is not known, but seems to be associated with immune system problems. Cirrhosis—scarring of the liver tissue, is caused by prolonged heavy alcohol use. Cirrhosis can lead to liver failure and may cause death. Cirrhosis Cirrhosis Scarring of the liver tissue caused by prolonged heavy alcohol use. Scarring of the liver tissue caused by prolonged heavy alcohol use. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System Structural Problems Appendicitis can cause the appendix to burst, spreading infection throughout the abdomen, which can lease to death. New Vocabulary appendicitis Inflammation of the appendix. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System Structural Problems Peptic ulcers can be caused by a bacterial infection or the overuse of aspirin. They can cause stomach bleeding. New Vocabulary Peptic ulcer A sore in the lining of the digestive tract. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System Structural Problems Cirrhosis is caused by prolonged heavy alcohol use. It can lead to liver failure and may cause death. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System After You Read Reviewing Facts and Vocabulary What functions of the digestive system take place in the small intestine? Digestion and absorption. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

LESSON 3 The Digestive System After You Read Reviewing Facts and Vocabulary Describe the actions that cause food to move through the digestive tract. A series of involuntary muscle contractions, called peristalsis. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

After You Read What are three behaviors that help prevent indigestion? LESSON 3 The Digestive System After You Read Reviewing Facts and Vocabulary What are three behaviors that help prevent indigestion? Sample answer: Eat less food, eat meals slowly, and chew food thoroughly. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson Home

Glencoe Health End of Chapter 15 Cardiovascular, Respiratory, and Digestive Systems Lesson 3 The Digestive System Lesson Home