The canine small intestine has the structure of a tube and connects the stomach to the large intestine. This organ contains three segments:
The duodenum receives food traveling from the stomach (chyme) that has combined with water, hydrochloric acid and various digestive enzymes. The chyme passes through the pyloric sphincter allowing substances to only travel in the proper direction forward. The pH level of chyme needs to be raised do to the high acidic level, the duodenum secretes the hormone, cholecystokinin (CCK), which causes the gall bladder to contract, releasing alkaline bile into the duodenum. Bile begins the process of raising pH, the duodenum then produces the hormone secretin to stimulate the pancreatic secretion of large amounts of sodium bicarbonate to balance the chyme’s pH to 7. Enzymes delivered by the liver now allow the extraction of nutrients to begin.
The jejunum is the longest area of the small intestine and is rich in small, finger-like projections called villi. Villi protrude inward into the food contents and provide a large surface area to absorb nutrients. Intestinal contents of the jejunum empty into the ileum and from there pass into the large intestine.
