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Nutrition Why do we eat? The foods we eat provide the nutrients our bodies need for energy, growth, and tissue repair. Digestion is the process of breaking down food in order to extract the nutrients and make them useable by the body. Types of Nutrients (You should know these!) Micronutrients- vitamins & minerals Macronutrients- proteins, fats, carbohydrates And water… Four Stages of Digestion 1. Ingestion 2. Digestion 3. Absorption 4. Egestion Four Stages of Digestion 1. Ingestion taking substances into the body through the mouth 2. Digestion 3. Absorption 4. Egestion Four Stages of Digestion 1. Ingestion 2. Digestion The breaking-down of large, insoluble food molecules into small water-soluble molecules. 3. Absorption 4. Egestion Digestion… begins in the mouth 1)MECHANICAL DIGESTION The teeth breaks up food & the tongue moves it around Digestion… begins in the mouth 2) CHEMICAL DIGESTION saliva amylase: an enzyme that digests starch mucin: a protein present in mucus that protects soft lining of digestive system and lubricates food for easier swallowing buffers: neutralize acid to prevent tooth decay anti-bacterial chemicals: kill bacteria that enter mouth with food Which type of digestion is the following? 1. Chewing a saltine? - 2. Saliva breaking the saltine down into molecules of glucose? 3. Your tongue breaking pieces of a hamburger apart? 4. Pepsin (an enzyme) in your stomach breaking the hamburger into amino acids? Digestion… then moves to the esophagus The esophagus is a muscular tube that carries food and liquids from the mouth to the stomach. Esophagus Food moves through the Esophagus to the Stomach by Peristalsis Peristalsis: a series of involuntary wave-like muscle contractions which move food along the digestive tract Digestion… then moves to the stomach The stomach stores swallowed food and liquid, mixes the food and liquid with digestive juice it produces, and slowly empties its contents, called chyme, into the small intestine. Four Stages of Digestion 1. Ingestion 2. Digestion 3. Absorption movement of digested food molecules through the wall of the intestine into the blood 4. Egestion Absorption… begins in the small intestine The walls of the small intestine absorb the digested nutrients into the bloodstream. The blood delivers the nutrients to the rest of the body. Small intestine Structure: 3 sections 1. duodenum = mostly digestion 2. jejunum = absorption of nutrients & water 3. ileum = absorption of nutrients & water Absorption… and finishes in the large intestine The large intestine absorbs water and any remaining nutrients and changes the waste from liquid into stool. Rectum Last section of colon (large intestine) Stores feces (undigested material) for elimination mainly cellulose from plants roughage or fiber Four Stages of Digestion 1. Ingestion 2. Digestion 3. Absorption 4. Egestion passing out of food that has not been digested, as feces, through the anus Egestion… The elimination or removal of undigested or waste material from a cell or organism.