2.7 Duodenum

• • Complete digestion takes place in the duodenum.

• • Above: The small intestine consists of three main regions. The first region is the duodenum. Duodenum receives bile from the gall bladder and pancreatic juice from the pancreas.

  • Duodenum receives:

  • 1. Bile from gall bladder

  • 2. Pancreatic juice from pancreas

  • Duodenum produces

  • 1. intestinal juice.

7.1 Bile

• Bile is released from gall bladder.

• Bile emulsifies fats into smaller droplets.Emulsification of fats leads to increased surface area to volume ratio for lipase to act on. This leads to faster rate of digestion of fats.

7.2 Pancreatic juice

• Bicarbonate ions (alkaline in nature) neutralize the acidic contents which leave the stomach and enter the duodenum.

• Alkaline environment inhibits the action of pepsin on proteins.

• Enzymes found in pancreatic juice include amylase, trypsin and pancreatic lipase

amylase

starch ------------> maltose

trypsin

proteins ----------> polypeptides

pancreatic lipase

fats -------------> fatty acids + glycerol

7.3 Intestinal enzymes

• Intestinal enzymes (eg. erepsin, lipase, maltase, sucrase and lactase)are secreted by the intestinal epithelial cells.

erepsin

polypeptides -----> amino acids

maltase

maltose -----> glucose + glucose

sucrase

sucrose ------> glucose + fructose