The Pancreas and Liver The pancreas lies behind the stomach and is an elongate, pinkish-gray organ with a lumpy texture and very soft tissue. Pancreatic islets secrete the hormones insulin and glucagon, but these cells represent only about 1% of total cells in the pancreas. Exocrine cells produce pancreatic juice, which is a mixture of digestive enzymes and buffers. The numerous ducts that branch throughout the pancreas end in saclike pouches called pancreatic acini. These small ducts converge to form larger ducts and ultimately the pancreatic duct, which ultimately penetrates the duodenal wall along with the common bile duct of the liver and gallbladder. The pancreas delivers carbohydrases, which digest sugars and starches, lipases which digest fats,

nucleases which break down nucleic acids, and proteases which break down proteins. 70% of total pancreatic enzyme production is proteases with the most common being trypsin, chymotrypsin and carboxypeptidase. The liver is a firm, reddish-brown organ that is the largest in the body. It is divided into 4 unequal lobes: the large left and right lobes and the smaller caudate and quadrate lobes. The liver is responsible for 3 general functions. First, it regulates the composition of circulating blood. All blood leaving the digestive tract flow through the liver before reaching general circulation. Thus, hepatocytes (liver cells) extract toxins before they reach the rest of the body and adjust the circulating levels of organic nutrients.

The liver is the largest blood reservoir in the body, receiving about 25% of cardiac output. Secondly, the liver removes aged or damaged red blood cells, debris, and pathogens from circulation by way of phagocytic Kupffer cells. Lastly, the liver synthesizes bile and excretes it into the duodenum. Bile consists of water, ions, bilirubin (a pigment derived from hemoglobin), cholesterol and lipids known as bile salts. The water and ions help dilute and buffer acids in chyme. Bile salts are synthesized from the cholesterol and aid in the digestion and absorption of fats. Dietary lipids (fats) are not water soluble and pancreatic lipase is not lipid soluble, so the bile salts break down the lipids first through a process called emulsification then pancreatic lipase breaks it down further.

1st Left Side Activity Draw, color and label a Radial Map entitled Pancreas (in the middle circle). This radial map must include the following words with information in their own circles: Lipases, nucleases, carbohydrases, proteases, trypsin, chymotrypsin and carboxypeptidase (you will need to look in your textbook for information on the last 3) 2nd Left Side Activity Write a letter (minimum 10 sentences) to the Chyme in your duodenum as if you are Bile. Tell the chyme what you are doing to it and explain what you can break down. Tell the chyme what enzymes released by the pancreas will be along soon to break down everything else. 3rd Left Side Activity Write a 10 line alternating Rhyming Poem on any subject you want from this lecture.