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UNIT B: Human Body Systems

Chapter 8: Human Organization Chapter 9: Digestive System: Section 9.3 Chapter 10: Circulatory System and Lymphatic System Chapter 11: Respiratory System Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System. UNIT B: Human Body Systems. UNIT B.

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UNIT B: Human Body Systems

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  1. Chapter 8: Human Organization Chapter 9: Digestive System: Section 9.3 Chapter 10: Circulatory System and Lymphatic System Chapter 11: Respiratory System Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System UNIT B: Human Body Systems

  2. UNIT B Chapter 9: Digestive System In this chapter, you will learn about the structure and function of the digestive system. Chapter 9: Digestive System • What is our current understanding of the structure and function of the digestive system, including the stomach? • Which substances produced by the stomach and other organs help with the chemical breakdown of foods? Alexis St. Martin was an unexpected live test subject for Dr. William Beaumont’s research on how the digestive system works. TO PREVIOUS SLIDE

  3. UNIT B Chapter 9: Digestive System Section 9.3 Digestive enzymes help break down the major components of food: carbohydrates, proteins, nucleic acids, and fats. 9.3 Digestive Enzymes TO PREVIOUS SLIDE

  4. UNIT B Chapter 9: Digestive System Section 9.3 Carbohydrate Digestion by Enzymes The digestion of starch (a carbohydrate) begins in the mouth. Salivary amylase (produced by the salivary glands) digests starch into maltose (a disaccharide) Pancreatic amylase(produced by the pancreas) and maltase (produced by the small intestine) then convert maltose in the small intestine to glucose (a monosaccharide). Glucose can be absorbed by the small intestine. TO PREVIOUS SLIDE

  5. UNIT B Chapter 9: Digestive System Section 9.3 Figure 9.11 Digestion and absorption of nutrients. a. The breakdown of carbohydrates, such as starch, involves amylase enzymes. TO PREVIOUS SLIDE

  6. UNIT B Chapter 9: Digestive System Section 9.3 Carbohydrate Digestion by Enzymes Other disaccharides, such as lactose, have their own enzyme that digests them in the small intestine. Lactaseis an enzyme that digests lactose, a sugar found in milk. Individuals who have a lactase deficiency often have symptoms of lactose intolerance (diarrhea, gas, cramps) caused by the fermentation of non-digested lactose by intestinal bacteria TO PREVIOUS SLIDE

  7. UNIT B Chapter 9: Digestive System Section 9.3 Protein Digestion by Enzymes The digestion of proteins begins in the stomach. Pepsin is an enzyme produced by gastric glands that acts on proteins to produce peptides. Trypsin (produced by the pancreas) and peptidases (produced in the small intestine) break down peptides into amino acids TO PREVIOUS SLIDE

  8. UNIT B Chapter 9: Digestive System Section 9.3 Figure 9.11 Digestion and absorption of nutrients. b. Protein digestion involves the action of protease enzymes. TO PREVIOUS SLIDE

  9. UNIT B Chapter 9: Digestive System Section 9.3 Fat Digestion by Enzymes Lipase (produced by the pancreas) acts in the small intestine and digests fat molecules in the fat droplets after they have been emulsified by bile salts Glycerol and fatty acids enter the cells of the villi, where they are rejoined and repackaged as lipoprotein droplets (chylomicrons) before entering the lacteals TO PREVIOUS SLIDE

  10. UNIT B Chapter 9: Digestive System Section 9.3 Figure 9.11 Digestion and absorption of nutrients. c. For fat digestion, bile salts emulsify the fats so that lipase enzymes can digest the particles. TO PREVIOUS SLIDE

  11. UNIT B Chapter 9: Digestive System Section 9.3 Enzymes function best at an optimum temperature and pH that helps maintain the proper shape to fit their substrate. Since the digestive system is maintained at a constant 37ºC, enzymatic activity is largely controlled by pH The pH of the stomach is between 1 and 2 but can increase to around 7.4 to 7.8 when sodium bicarbonate in pancreatic juice is released from the pancreas This increase in pH occurs after chyme enters the duodenum, and allows different digestive enzymes to be active depending on the pH Regulation of Digestive Enzymes TO PREVIOUS SLIDE

  12. UNIT B Chapter 9: Digestive System Section 9.3 Describe where in the digestive tract the chemical digestion of each of the following types of nutrients occurs: carbohydrates, proteins, and fats. Identify the final molecule (monomer) resulting from the digestion of carbohydrates, proteins, and fats. Explain how the structure of the digestive system assists in regulating the digestive enzymes. Check Your Progress TO PREVIOUS SLIDE

  13. UNIT B Chapter 9: Digestive System Section 9.3 TO PREVIOUS SLIDE

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