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The Digestive process

The Digestive process. Chapter 15 Section 2. Functions of the Digestive System. Three main functions Breaks down food into molecules the body can use Molecules are absorbed into the blood and carried throughout the body Waste in then eliminated from the body. Digestion.

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The Digestive process

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  1. The Digestive process Chapter 15 Section 2

  2. Functions of the Digestive System • Three main functions • Breaks down food into molecules the body can use • Molecules are absorbed into the blood and carried throughout the body • Waste in then eliminated from the body

  3. Digestion • The process by which the body breaks down food into small nutrient molecules • Two kinds of digestion • Mechanical • Foods are physically broken down into smaller pieces • Occurs when you bite into a sandwich and chew it into small pieces • Chemical • Chemicals produced by body break foods into their smaller chemical building blocks • Starch in bread… into sugar

  4. Absorption and Elimination • Process by which nutrient materials pass through the wall of the digestive system and into the blood • Food that is not absorbed are eliminated from the body as waste

  5. The Digestive System

  6. Digestive System Functions • Esophagus – tube that connects the mouth to the stomach, contracts to push food down • Stomach – muscular pouch that holds swallowed food, does most mechanical digestion and some chemical digestion • Pancreas – triangular organ that produces enzymes that help break down starches, proteins and fats in small intestine • Rectum – short tube at end of large intestine, compresses waste into a solid form • Small Intestine – long, narrow tube where almost all chemical digestion and absorption of nutrients happens • Large Intestine – last section of digestive system, absorbs water and prepares waste for elimination

  7. The Mouth • Mechanical and chemical digestion begins in the mouth • Saliva: fluid released when your mouth waters • Teeth carry out the first stage of mechanical digestion • Chemical digestion in the mouth… • an enzyme in saliva breaks down starch into sugar molecules • Enzyme: protein that speeds up chemical reactions in the body

  8. The Esophagus • Epiglottis: a flap of tissue that seals off the windpipe, preventing food from entering • Esophagus: a muscular tubes that connects the mouth to the stomach • The esophagus is lined with mucus: a thick, slippery substance produced by the body, it makes food easier to swallow • After food enters esophagus, contractions of smooth muscle push food toward the stomach • Peristalsis: involuntary waves of muscle contraction that push food through the digestive system

  9. The Stomach • Stomach: J-shaped, muscular pouch located in the abdomen • Most mechanical digestion and some chemical digestion occur in the stomach • Mechanical Digestion in the Stomach • Three strong layers of smooth muscle contract to produce the churning motion • Chemical Digestion in the Stomach • Digestive juice in the stomach contains an enzyme (pepsin)that breaks down proteins

  10. Why doesn’t stomach acid burn a hole in your stomach? • Cells in the stomach produce a thick coating of mucus, protects stomach lining • Cells that line the stomach are quickly replaced as they are damaged or worn out

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