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6.1 – Digestion

6.1 – Digestion. Discuss as a table. What are the 4 major macromolecules? What are the polymers and monomers of each one?. Essential Idea: The structure of the wall of the small intestine allows it to move, digest and absorb food. Purpose of digestion

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6.1 – Digestion

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  1. 6.1 – Digestion

  2. Discuss as a table What are the 4 major macromolecules? What are the polymers and monomers of each one?

  3. Essential Idea: The structure of the wall of the small intestine allows it to move, digest and absorb food.

  4. Purpose of digestion A. Food is made of cells, and therefore macromolecules (carbs, lipids, proteins, nucleic acids) that your body needs to function

  5. B. Macromolecules are too big to cross cell membranes C. Your digestive system breaks polymers down into monomers so that they can get into your cells

  6. D. Your cells use the monomers to build macromolecules (this is called assimilation)

  7. 4 steps • Ingestion – eat • Digestion – break down into smaller molecules • Absorption – molecules move from digestive tract into blood and lymph • Transport – circulatory system delivers molecules to cells

  8. III. Structures of the Alimentary Canal A. Mouth – Chemical and mechanical digestion 1. Salivary glands – produce saliva which lubricates food for travel to stomach and contains enzymes to chemically digest carbohydrates a. Salivary amylase – Breaks starch/complex carbs down to maltose (a disaccharide of glucose)

  9. B. Esophagus – move food to stomach 1. Peristalsis – smooth muscle contractions https://www.youtube.com/watch?feature=endscreen&NR=1&v=o18UycWRsaA

  10. Stomach – Chemical and mechanical digestion 1. Produces chyme – mixture of food, digestive enzymes, and stomach acid 2. Gastric juices – contain pepsin – an enzyme that breaks down proteins to amino acids a. Hydrochloric acid (HCl) – a cofactor required for pepsin to work – makes pH of stomach about 2

  11. Small Intestine – Chemical digestion and nutrient absorption into the blood • 3 parts – duodenum, jejunum, ileum • Chemical digestion – mostly in duodenum and jejunum a. Trypsin to break down proteins, pancreatic amylase to break down carbs, pancreatic lipase to break down lipids to glycerol and fatty acids *These three enzymes are produced by the pancreas

  12. Muscle Contractions – circular and longitudinal muscles alternate contractions in order to push food through the digestive tract

  13. 4. Absorption – starts in the jejunum, mostly in the ileum a. Monomers are absorbed from the lumen of the small intestine into the blood

  14. Villi – finger-like projections lining the small intestine, increase surface area i. Each one contains capillaries (blood vessels) and a lacteal (lymph vessels) ii. Monomers of carbs and proteins go to blood, subunits of lipids go to lymph iii. Blood goes from the intestines straight to the liver for detoxification https://www.youtube.com/watch?v=0oBNJTP49Mw&feature=related

  15. Large Intestine – Water reabsorption (maintains water balance – diarrhea, constipation) 1. 3 parts – ascending, transverse, descending 2. Millions of e.coli in symbiotic relationship – they get food, shelter, and they produce vitamin K for us F. Rectum – stores waste until elimination • Anus – elimination waste from the body

  16. With a partner Discuss what you had for dinner last night, how it has moved through your digestive tract since then, and what has happened to that food at each major structure of the alimentary canal.

  17. IV. Accessory organs and their functions A. Liver – produces bile (helps digest fats), detoxifies blood, creates glycogen for carbohydrate storage

  18. B. Gall bladder – stores and concentrates bile

  19. C. Pancreas 1. Exocrine function – products are released through a duct into the duodenum a. Produces digestive enzymes – pancreatic amylase, pancreatic lipase, trypsin b. Produces sodium bicarbonate to neutralize stomach acid in the small intestine • *** All three accessory organs feed into the same duct into the duodenum***

  20. 2. Endocrine function – hormones released into the blood a. Produces hormones that regulate blood sugar - insulin (lowers blood sugar) and glucagon (raises blood sugar)

  21. Review as a table What are hydrolysis and condensation reactions? What is their function and what does each type of reaction look like chemically?

  22. V. Digestion is an enzyme-driven process A. Digestive enzymes catalyze hydrolysis reactions – hold macromolecules in place and stress bonds until body heat causes them to break

  23. https://www.youtube.com/watch?v=_rucrIv-EUA

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