UNIT B: Human Body Systems

2. Chapter 8: Human Organization Chapter 9: Digestive System: Section 9.2 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

3. 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

4. UNIT B Chapter 9: Digestive System Section 9.2 The accessory digestive organs are the pancreas, liver, and gall bladder. 9.2 Accessory Organs of Digestion Figure 9.8 Liver, gall bladder, and pancreas. a. The liver makes bile, which is stored in the gall bladder and sent (black arrow) to the small intestine by way of the common bile duct. The pancreas produces digestive enzymes that are sent (black arrows) to the small intestine by way of the pancreatic duct. TO PREVIOUS SLIDE

5. UNIT B Chapter 9: Digestive System Section 9.2 The pancreas is an organ that has both endocrine and exocrine functions. Exocrine function of the pancreas Pancreatic cells produce pancreatic juice (to neutralize stomach acid) and digestive enzymes Endocrine function of the pancreas Pancreas secretes insulin and glucagon, hormones that regulate blood glucose (sugar) levels The Pancreas TO PREVIOUS SLIDE

6. UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Pancreas The pancreas contains pancreatic islets (islets of Langerhans), which are clusters of at least three types of endocrine cells: Alpha cells: produce glucagon Beta cells: produce insulin Delta cells: produce somatostatin TO PREVIOUS SLIDE

7. UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Pancreas Insulin Hormone secreted when blood glucose level is high Stimulates the uptake of glucose by cells (liver, muscle, adipose tissue) to lower blood glucose Glucagon Hormone secreted when blood glucose level is low Stimulates the liver to break glycogen down into glucose to increase blood glucose Stimulates adipose tissue to break fat down to glycerol and fatty acids (to make glucose) TO PREVIOUS SLIDE

8. UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Pancreas Somatostatin A growth-hormone-inhibiting hormone Also produced by cells in the stomach and small intestine Inhibits the release of growth hormone Suppresses the release of insulin and glucagon Decreases the absorption of nutrients TO PREVIOUS SLIDE

9. UNIT B Chapter 9: Digestive System Section 9.2 Figure 9.9 Regulation of blood glucose level. Top: When the blood glucose level is high, the pancreas secretes insulin. Insulin promotes the storage of glucose as glycogen and the synthesis of proteins and fats (as opposed to their use as energy sources). Therefore, insulin lowers the blood glucose level to normal. TO PREVIOUS SLIDE

10. UNIT B Chapter 9: Digestive System Section 9.2 Bottom: When the blood glucose level is low, the pancreas secretes glucagon. Glucagon acts opposite to insulin. Therefore, glucagon raises the blood glucose level to normal. TO PREVIOUS SLIDE

11. UNIT B Chapter 9: Digestive System Section 9.2 The liver is the largest gland in the body. The liver has many functions, including: Detoxifying blood Making plasma proteins Maintaining blood glucose levels Producing bile, which contains bile salts that emulsify fat in the small intestine Producing urea, a nitrogenous waste product from the breakdown of amino acids The Liver TO PREVIOUS SLIDE

12. UNIT B Chapter 9: Digestive System Section 9.2 TO PREVIOUS SLIDE

13. UNIT B Chapter 9: Digestive System Section 9.2 Structure and Function of the Liver The liver contains about 100 000 lobules that serve as its structural and functional units. Three structures are located between the lobules: Bile duct: takes bile away from the liver Hepatic artery branch: brings oxygen-rich blood to the liver Hepatic portal vein: transports nutrients from the intestines TO PREVIOUS SLIDE

14. UNIT B Chapter 9: Digestive System Section 9.2 Figure 9.8 b. A hepatic lobule. The liver contains over 100 000 lobules, each lobule composed of many cells that perform the various functions of the liver. They remove and add materials to the blood and deposit bile in a duct. TO PREVIOUS SLIDE

15. UNIT B Chapter 9: Digestive System Section 9.2 Figure 9.10 Hepatic portal system. The hepatic portal vein takes the products of digestion from the digestive system to the liver, where they are processed before entering a hepatic vein. TO PREVIOUS SLIDE

16. UNIT B Chapter 9: Digestive System Section 9.2 The gall bladder is a muscular sac attached to the surface of the liver. Excess bile from the liver is stored in the gall bladder Bile leaves the gall bladder and proceeds to the duodenum via the common bile duct Bile emulsifies fat to prepare it for further breakdown by digestive enzymes The Gall Bladder TO PREVIOUS SLIDE

17. UNIT B Chapter 9: Digestive System Section 9.2 Describe how pancreatic hormones regulate blood glucose levels. Explain why the liver is necessary for life, whereas the gall bladder can be removed with few consequences. Check Your Progress TO PREVIOUS SLIDE

18. UNIT B Chapter 9: Digestive System Section 9.2 TO PREVIOUS SLIDE