Digestion Objectives: Students will be able to describe the 3 main functions of the digestive system. Students will be able to identify the organs of the digestive system and their functions. Indian Hills Middle School

Functions of the Digestive System The digestive system has 3 main functions: Digestion Absorption Elimination

Digestion There are 2 kinds of digestion: The process by which the digestive system breaks down food into molecules that the body can use. There are 2 kinds of digestion: Mechanical Foods are physically broken into smaller pieces Chemical Chemicals produced by your body break large molecules into smaller ones that your body can use. Enzymes: chemicals that speed up the digestion process

Absorption & Elimination Process by which nutrients pass through the lining of your digestive system into your blood. The blood then transports the nutrients throughout the body. Materials that are not absorbed are eliminated from the body as wastes. Where is this chicken salad sandwich going?

Structures of the Digestive System: The mouth, pharynx, esophagus, stomach, small intestine, and large intestine. The liver, gallbladder, and pancreas all aid in digestion. MOUTH PHARYNX Mechanical digestion occurs in your mouth as teeth tear and crush and the tongue moves the food around The junction between the digestive tract and the respiratory system. Epiglottis is a flap of tissue that seals off the windpipe or trachea preventing food and liquid from entering your lungs Chemical digestion occurs as an enzyme in saliva begins to break down starches in the food. Saliva moistens the bites of food into a slippery mass that can be easily swallowed.

Structures of the Digestive System ESOPHAGUS STOMACH A small muscular tube that connects the pharynx to the stomach. Food passes through a valve into the stomach. The stomach can hold 1 gallon of food or water. Mechanical digestion occurs as 3 layers of muscle tissue churn the food. Gastric juices help break down food creating a chemical reaction. Gastric acid kills bacteria in food. The food has been turned into chyme and moves into the small intestine. Muscles contract, peristalsis, and push the food through the esophagus toward the stomach.

Structures of the Digestive System Small Intestines Most chemical digestion and absorption of nutrients takes place in this 20’ long tube. The liver produces bile that breaks up fat droplets that clump together. The gallbladder is a small storage space that holds the bile from the liver. The pancreas secretes enzymes into the small intestine that breaks down carbs, proteins, & fat.

Structures of the Digestive System Small Intestine Millions of villi found in the small intestines absorb nutrient molecules into the blood system.

Structures of the Digestive System The Large Intestine When the material reaches the end of the small intestine, most nutrients have been absorbed. It then moves into the large intestines also called the colon for about 12-24 hours. Some absorption takes place with the remaining water. Produces vitamins in the large intestines. The rectum collects the waste called feces or stool and eliminates it through the anus.

Structures of the Digestive System Can you follow the path of the chicken salad sandwich? 1 2 4 3 5 6 8 7 9 10 11

Healthy Review & Questions List the three main functions of the digestive system in the order that they occur. What is digestion and name the two kinds of digestion? Where does digestion begin and what kind of digestion is it? What is peristalsis? What does the stomach do to the food? What organ absorbs most of the nutrients from the food into the bloodstream to be used as energy?