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Warm-Up in spiral What is the difference between mechanical and chemical digestion? The Digestive System Three functions & processes of the digestive system… Digestion=> Body breaks down food. Absorption=> Food molecules enter the blood & are carried to cells. Elimination=> Wastes pass out of the body. Two kinds of digestion… Mechanical digestion… food is physically broken down into smaller pieces by chewing & churning. Chemical digestion… food is chemically broken into smaller molecules by enzymes. Enzymes… Proteins that speed up chemical reactions in the body. (saliva, pepsin, hydrochloric acid) Organs food pass through… Mouth=> Esophagus=> Stomach=> Small intestine=> Large intestine=> Rectum=> Anus Accessory organs that aid in digestion… Liver & gall bladder Pancreas The Path and Processes Mouth… mechanical digestion=> teeth chemical digestion=> saliva Esophagus… muscular tube that connects the mouth to the stomach Peristalsis… Involuntary smooth muscle contractions move food in one direction through the digestive system (unless vomiting due to homeostasis!). Stomach… Muscular pouch in the abdomen… mechanical digestion=> churning chemical digestion=> pepsin & hydrochloric acid During digestion, the human body must use mechanical and chemical energy to breakdown compounds. The chemical energy in these compounds can then be used or transferred into thermal energy (to increase body temperature) or mechanical energy (to grow or to move). Mucus protects your stomach lining from being digested. Small intestine… Most chemical digestion & absorption of nutrients into the blood stream occurs here. Food mixes with enzymes & chemicals secreted into the small intestine by the liver (gall bladder) & pancreas. Villi… millions of tiny finger shaped structures that line the walls of the small intestine to provide more surface area for nutrient absorption into bloodstream. Liver… produces bile to physically break down fats (like dish soap on grease). Gall bladder… stores bile produced by the liver & passes it into the small intestine. Pancreas… produces enzymes that flow into the small intestine & help complete chemical digestion. Pancreas… Helps to maintain homeostasis by insulin production that controls blood sugar levels Large intestine… water is absorbed into the blood stream & the remaining fiber & undigested food is prepared for elimination. Rectum… short section at the end of the large intestine where waste is compressed into solid form. Anus… muscular opening at the end of the rectum where wastes exit the body. Organic Compounds Compounds containing carbon and other elements such as hydrogen, oxygen, phosphorus, nitrogen, or sulfur. Come from living material such as plants and animals. Carbohydrates Starches and sugars are a source of energy Examples potatoes, fruits, cereal, flour, pastas Carbohydrates Mechanical Digestion Chewed and broken into smaller pieces; moved down the digestive tract through peristalsis Chemical Digestion Digestive enzymes in the mouth, stomach, and small intestine break bonds so that carbohydrate become simple sugars Proteins Build new cells (muscle, skin, hair) and repair damaged cells Examples meats, eggs, peanuts, beans Proteins Mechanical Digestion Chewed and broken into smaller pieces; moved down the digestive tract through peristalsis Chemical Digestion Digestive enzymes in the stomach and small intestine break peptide bonds so that proteins become amino acids Lipids Energy, insulation, and essential building block for cells Examples fats, oils Lipids Mechanical Digestion Chewed and broken into smaller pieces; moved down the digestive tract through peristalsis Chemical Digestion Digestive enzymes in the mouth, stomach, and small intestine break bonds so that lipids become fatty acids and glycerol