1. Section 10.1 Your Digestive System Slide 1 of 21 Objectives Describe the three main functions of the digestive system. Identify the organs of the digestive system and their functions. Section 10.1 Your Digestive System

2. Section 10.1 Your Digestive System Slide 2 of 21 Myth Food is digested in the stomach. Fact Although protein digestion does begin in the stomach, most digestion occurs in the small intestine. List three questions you have about how the digestive system functions. Look for the answers in the chapter.

3. Section 10.1 Your Digestive System Slide 3 of 21 Your digestive system has three main functions Functions of the Digestive System digestion absorption elimination

4. Section 10.1 Your Digestive System Slide 4 of 21 The process by which the digestive system breaks down food into molecules that the body can use is called digestion. Digestion During mechanical digestion, foods are physically broken apart into smaller pieces. During chemical digestion, chemicals produced by your body break large molecules into smaller ones that your body can use. Most of the chemicals involved in digestion are enzymes, substances that speed up reactions.

5. Section 10.1 Your Digestive System Slide 5 of 21 Absorption is the process by which nutrients pass through the lining of your digestive system into your blood. Absorption and Elimination Materials that are not absorbed are eliminated from the body as wastes.

6. Section 10.1 Your Digestive System Slide 6 of 21 Click above to go online. For: More on the digestive system

7. Section 10.1 Your Digestive System Slide 7 of 21 The organs of the digestive system include the Structures of the Digestive System mouth pharynx esophagus stomach small intestine large intestine liver gallbladder pancreas

8. Section 10.1 Your Digestive System Slide 8 of 21 Your teeth tear, crush, and grind your food. Mouth An enzyme in saliva begins to break down starches in your food. Saliva moistens the bites of food. Your tongue pushes the food around.

9. Section 10.1 Your Digestive System Slide 9 of 21 The pharynx is the junction between the digestive tract and the respiratory system. Pharynx A flap of tissue called the epiglottis seals off the trachea, or windpipe, preventing food and liquid from entering your lungs.

10. Section 10.1 Your Digestive System Slide 10 of 21 After passing through the pharynx, the food enters the esophagus, a muscular tube that connects the pharynx to the stomach Esophagus Waves of muscle contractions, called peristalsis, push food through the rest of the digestive system.

11. Section 10.1 Your Digestive System Slide 11 of 21 Pharynx Epiglottis Mouth Salivary gland Liver Esophagus Stomach Pancreas Small intestine Large intestine Rectum Gallbladder

12. Section 10.1 Your Digestive System Slide 12 of 21 Enzymes in Action In this activity, you will observe the effect on enzymes on foods. Materials crackers meat tenderizer milk orange juice 2 clear glasses 2 stirrers Chew a cracker for 5 seconds. Do not swallow it. Note how the cracker tastes. Try This

13. Section 10.1 Your Digestive System Slide 13 of 21 Enzymes in Action Place 2 tablespoons of milk into one glass. Place 2 tablespoons of orange juice into another glass. Add 1 tablespoon of meat tenderizer to each glass. Stir well with separate stirrers. After 30 minutes, look closely at the contents of the two glasses. Record your observations. Continue chewing the cracker for 5 minutes. Note how the taste of the cracker changes before swallowing it.

14. Section 10.1 Your Digestive System Slide 14 of 21 Enzymes in Action Why do you think the taste of the cracker changed the longer it was in your mouth? Think and Discuss After 30 minutes, how did the appearance of the milk solution compare to that of the orange juice solution? How did the taste of the cracker change during the five minutes it was in your mouth?

15. Section 10.1 Your Digestive System Slide 15 of 21 Enzymes in Action Think and Discuss Meat tenderizer contains an enzyme called papain. Based on your observations, what nutrient does papain act on? Why do you think meat tenderizer makes cooked meat tender?

16. Section 10.1 Your Digestive System Slide 16 of 21 From the esophagus, food passes through a valve and into the stomach, a muscular pouch located in the abdomen. Stomach Mechanical digestion occurs as three layers of muscle produce a churning motion. Chemical digestion occurs as cells lining the stomach release gastric juice. Peristalsis moves the food, which is now a thick liquid called chyme (kym), into the small intestine.

17. Section 10.1 Your Digestive System Slide 17 of 21 The small intestine is where most chemical digestion and absorption of nutrients takes place. Small Intestine Liver The role of the liver is to produce bile. Bile is a substance that physically breaks up large fat droplets that clump together. Gallbladder Bile flows from the liver into the gallbladder, the organ that stores bile. Pancreas The pancreas secretes enzymes into the small intestine that complete the breakdown of carbohydrates, proteins, and fats. The lining of the small intestine is covered with millions of tiny fingerlike projections called villi (singular, villus).

18. Section 10.1 Your Digestive System Slide 18 of 21 The large intestine is about 5 feet long and 3 inches wide. The Large Intestine As the material moves through the large intestine, most of the remaining water is absorbed into the blood.

19. Section 10.1 Your Digestive System Slide 19 of 21 Vocabulary digestionThe process by which the digestive system breaks down food into molecules that the body can use. enzymeA chemical that speeds up reactions in the body. absorptionThe process by which nutrients pass through the lining of the digestive system. pharynxThe upper portion of the throat; the junction between the digestive and respiratory systems. epiglottisA flap of tissue that seals off the trachea when food or liquid is swallowed. peristalsisWaves of muscle contractions that push food through the digestive system.

20. Section 10.1 Your Digestive System Slide 20 of 21 Vocabulary chymeA thick mixture of food and gastric juices formed in the stomach. bile A substance produced by the liver that aids in digestion by breaking up large fat droplets. gallbladder The organ that stores bile and releases it into the small intestine. villiTiny fingerlike projections lining the small intestine, through which nutrients are absorbed into the blood.

21. Section 10.1 Your Digestive System Slide 21 of 21 QuickTake Quiz Click to start quiz.

22. Section 10.1 Your Digestive System Slide 22 of 21 End of Section 10.1 Click on this slide to end this presentation.