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Understanding the Digestive System: Stages of Food Processing

The digestive system processes food through four key stages: ingestion, digestion, absorption, and elimination. Mechanical and chemical digestion involves the breakdown of food into smaller molecules using enzymes. The journey starts in the mouth and extends through the esophagus, stomach, small intestine, and large intestine. Key organs and accessory structures, such as the pancreas and liver, play vital roles in nutrient absorption and waste elimination. Enzymes like amylase and pepsin facilitate these processes, making it essential for our body's function and health.

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Understanding the Digestive System: Stages of Food Processing

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  1. Ch. 7.2 The Digestive System

  2. 1. stages in food processing ingestion digestion absorption elimination - the process that breaks down food into small molecules so that they can be absorbed and moved into the blood 2. digestion

  3. 3. mechanical digestion - takes place when food is chewed, mixed, and churned 4. chemical digestion - chemical reactions occur that break down large molecules of food into smaller ones

  4. 5. What happens after digestion? • from blood, food molecules transported across cell membrane to be used by the cell • unused molecules leave your body as wastes 6. enzyme • a type of protein that speeds up the rate of a chemical reaction in your body • some reduce the amount of energy needed for a chemical reaction to begin

  5. 7. enzymes in digestion • amylase- made in glands near mouth, help speed up breakdown of complex carbs • pepsin- in stomach, breaks down complex proteins • pancreas releases enzymes into small intestine- some break down starches, some break down fats, and some break down proteins

  6. 8. organs of the digestive system - mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus - tongue, teeth, salivary glands, liver, gallbladder, and pancreas 9. accessory organs

  7. mechanical digestion- chew your food • chemical digestion- food mixes with saliva • saliva- mostly water, also mucus and an enzyme that breaks down starch into sugar • food is moved by tongue to back of mouth, swallowed, and passes into esophagus 10. mouth

  8. 11. esophagus • muscular tube about 25 cm long • takes 4 to 6 seconds for food to move through esophagus into stomach • mucous glands keep food moist, smooth muscle keeps food moving down by squeezing

  9. - waves of muscle contractions that move food through the entire digestive tract 12. peristalsis

  10. 13. stomach • a muscular bag with folds on the inside • mechanical digestion- food is mixed in stomach by peristalsis • chemical digestion- food mixed with enzymes and digestive solutions to break it down • acidic solution destroys bacteria in food • food moves through stomach in 2 to 4 hoursand is changed to chyme

  11. 14. chyme • thin, watery liquid made from stomach breaking down food, moves from stomach to small intestine

  12. small in diameter, 4 to 7 meters long • first part called duodenum- most digestion takes place here, bile from liver is added to food and breaks up fat particles • digestive solution from pancreas contains bicarbonate ions and enzymes- neutralize stomach acid • pancreas makes insulin which allows glucose to pass from bloodstream into cells • absorption takes place in folds and villi • nutrients move from villi into blood and to cells • undigested and unabsorbed food move into large intestine 15. small intestine

  13. - fingerlike projections on folds in small intestine 16. villi 17. large intestine • main job is to absorb water from the undigested mass in chyme • chyme can stay here for up to 3 days • rest of undigested food becomes more solid and passes through rectum and out through the anus

  14. bacteria is not always harmful • in large intestine feed on undigested material and make vitamins you need • breakdown of intestinal materials by bacteria produce gas 18. bacteria

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