Digestive Function In Humans

Digestive functions in humans is probably not something to which individuals are constantly attentive. The average individual will just enjoy a meal to satiate their appetite and maybe enjoy the flavors of the meal being consumed without giving much thought to the digestive processes that occur involuntarily within the body to sustain life. Without normal functioning of the digestive tract, many problems can present themselves and cause the individuals being affected to become more aware and attentive to keeping a homeostasis and maintenance in the presence of a pathological condition (which will be discussed later). A brief overview of normal digestive function will follow a straight forward pathway beginning with ingestion via the mouth where

Carbohydrates are necessary for a balanced diet and sustenance. However, for many people, one of the largest elements of an average diet consists rather heavily of carbohydrates. Humans enjoy carbohydrates; many times, in excess. Carbohydrates have shown to be evident in as high as forty-five percent of the daily caloric intake in humans(5). Digestion of carbohydrates begins in the mouth as mentioned earlier with the enzyme amylase which is present in the saliva. This breaks the carbohydrates into their simpler subunits (saccharide forms). In the stomach, the carbohydrates are converted into chyme with the peristaltic action of the stomach. Next, the chyme will pass into the duodenum. At the introduction to the duodenum, alpha amylase is secreted by the pancreas and further breaks down the carbohydrates into primary simple sugars. Then they are transported and absorbed by the small intestine via the villi on the epithelial lining of the lumen of the small intestine. The epithelium absorbs these simple saccharides (such as dextrin and maltose). These sugars, in their simplest forms (as glucose, fructose, or galactose), will enter the capillaries where they enter the blood stream via different transporters such as the GLUT transporter (a facilitative sugar transporter)(7). Fructose and galactose will enter the liver via the hepatic portal system where they are broken down to glucose. Glucose is already at an optimal state for use in tissues at the cellular level for use in glycolysis, so glucose will travel in the bloodstream to the intended tissues that require the glucose for energy. Insulin will allow the uptake of the glucose into the tissues and as one might imagine, is critical for blood glucose