Glencoe Health Lesson 3 The Digestive System

Pair/Share What are the three main processes (or functions) of Digestion? 30 Seconds…..

What Happens During Digestion 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. Three Main Processes of the Digestive System Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

Pair/Share When a person eats a piece of bread, what is the digestive path it follows? Name the digestive organs in order. 30 seconds…..

Main Idea How Digestion Works The digestive system consists of the mouth, esophagus, stomach, and intestines. Carbohydrates begin digesting in the mouth, Salivary glands produce enzymes like amylase, to help breakdown of food. Protein begins digesting in the stomach, and fats begin digesting in the small intestines. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

Pair/Share Digestion includes 2 processes, what are they? 30 seconds…

How Digestion Works Mechanical Processes Chewing, mashing, and breaking food down. Chemical Processes Secretions produced by digestive organs. Digestion includes two processes: Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

What is peristalsis?

peristalsis A series of involuntary muscle contractions that moves food through the digestive tract. peristalsis A series of involuntary muscle contractions that moves food through the digestive tract. New Vocabulary The Esophagus When food is swallowed, it moves through the esophagus, stomach, and intestines through peristalsis. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

What is pepsin?

gastric juices Secretions from the stomach lining that contain hydrochloric acid and pepsin, an enzyme that digests protein. gastric juices Secretions from the stomach lining that contain hydrochloric acid and pepsin, an enzyme that digests protein. New Vocabulary The Stomach The hydrochloric acid in gastric juices kills bacteria taken in with food and creates an acidic environment for pepsin to do its work. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

What is Chyme?

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. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

bile A yellow-green, bitter fluid important in the breakdown and absorption of fats. bile A yellow-green, bitter fluid important in the breakdown and absorption of fats. New Vocabulary 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. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

Pair/Share Which is bigger, the small intestine or the large intestine? Where does most of the absorption of nutrients take place? What do the villi do? 30 seconds…..

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. 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. The inner wall of the small intestine contains millions of fingerlike projections called villi that are lined with capillaries that absorb the nutrients. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home

The Large Intestines The undigested parts of the food – fiber, or roughage – pass into the colon, or large intestine. Its function is to absorb water, vitamins, and salts, and to eliminate waste. Glencoe Health Chapter 15 Cardiovascular, Respiratory, and Digestive Systems LESSON 3 The Digestive System Lesson Home