Digestive System - Pancreas

1. Digestive System - Pancreas Pgs. 916-918

2. Basics • Accessory organ • Chyme passes from stomach to small intestine through duodenum • Chemical digestion in small intestine depends on the activities of pancreas, liver, and gallbladder

3. Anatomy of Pancreas • Lies posterior to greater curvature of stomach • Connected to duodenum by 2 ducts

4. Anatomy of Pancreas - Pancreas composed of a head, body, and tail

5. Pancreatic Ducts - Pancreatic juices are secreted by exocrine cells into small ducts 2 larger ducts

6. Pancreas – Histology - 99% of pancreas = acini - small clusters of glandular epithelial cells - exocrine cells – secrete pancreatic juice • Other 1% = pancreatic islets (islets of Langerhans) - endocrine = secrete hormones glucagon, insulin, etc.

8. Pancreatic Juice • 1200-1500 mL produced on a daily basis • Consists of water, salts, sodium bicarbonate and many enzymes - sodium bicarbonate gives pancreas a pH between 7.1-8.2 - important = buffers acidic gastric juice in chyme, stops action of pepsin (stomach), and creates proper pH for digestive enzymes in small intestine

9. Pancreatic Enzymes Pancreatic amylase – digests starch Nucleic acid digesting enzymes – 1. ribonuclease 2. deoxyribonuclease Lipid digesting – pancreatic lipase (most triglycerides) Protein digesting enzymes = 1. trypsin 2. chymotrypsin 3. carboxypeptidase 4. elastase

10. Protein Digesting Enzymes • Most are produced in an inactive form (do not digest cells of the pancreas) Ex. – trypsin = inactive trypsinogen - acinar cells also produce trypsin inhibitor that will destroy any trypsin accidently formed in pancreas - trypsinogen into small intestine = enterokinase – converts trypsinogen into trypsin activates all other enzymes