1. Accessory Organs in Digestion & their Associated Enzymes

2. Accessory Organs Salivary glands Pancreas Liver Gallbladder

3. Salivary Glands Parotid glands secrete a watery fluid that contains salivary amylase. Buccal glands secrete a slippery fluid called mucus.

4. Liver Functions: – Regulates metabolism. – Removes toxins via catalase. – Excessive alcohol & drug use will lead to liver damage &/or death.

5. Liver Second largest organ in the body (1.5 kg). Synthesizes & secretes 1 L of bile per day. Bile acts as detergent to breakdown or emulsify fat. – Contains bile salts, bile acids, cholesterol, water, phospholipids, fatty acids & water.

6. Liver & Gallbladder The liver has a left and right lobe. The gallbladder is under the right lobe & stores and concentrates bile. When fat enters the duodenum: – CCK released. – Signals gallbladder to release bile through the bile duct & into the duodenum.

7. Liver & Gallbladder

8. Pancreas Finger-shaped organ (15 cm long). Located behind the stomach. Secretes hormones & digestive enzymes.

9. Pancreas The acidity of chyme triggers cells in the duodenum to release a hormone called secretin. Secretin enters the bloodstream, signaling the release of bicarbonate ions from the pancreas. Bicarbonate ions neutralize the HCl in the duodenum, raising the pH so that pepsin becomes inactive.

10. Pancreas Other pancreatic enzymes: – Lipases: digests lipids. – Carbohydrases/pancreatic amylase: digests sugars & starches. – Proteases: digests proteins. – Trypsinogen: released & activated (trypsin) in the small intestine to digest proteins.

11. Homeostasis (maintenance of steady internal state) Our bodies oppose changes to internal environment via negative feedback loops. Our bodies operate in a similar fashion as household thermostats.

12. Regulation of Blood Sugar After eating, blood sugar increases. – Receptors are activated & trigger the release of insulin from the pancreatic beta cells. – Insulin stimulates the uptake of glucose from the blood & into body cells. – This lowers the blood sugar level. – Receptors are deactivated & insulin secretion stops.

13. Regulation of Blood Sugar After fasting or prolonged exercise, blood sugar decreases. Receptors are activated & trigger the release of glucagon from the pancreatic alpha cells. This stimulates the breakdown of glycogen to release glucose molecules into the bloodstream. Receptors are deactivated & glucagon secretion stops.