The Purpose and Components of the Digestive System

Human beings have a long digestive tract.  Each track has its purpose and components. The process first begins by entering the food into the mouth.

Mouth is for chewing and mixing food with saliva.

Salivary Gland is to donate a starch-digesting enzyme. It is to donate a trace of fat-digesting enzyme.

Then it enters Esophagus which where it passes food to stomach.

Stomach adds acid, enzymes and fluid. It churns, mixes, and grinds food to a liquid mass.  While the food is in the stomach, the liver manufactures bile which is a detergent-like substance that facilitates digestion of fats.  Then Gallbladder stores bile until needed. 

Pancreas manufactures enzymes to digest all energy-yielding nutrients.  It releases bicarbonate to neutralize stomach acid that enters small intestine.

Once the stomach turns the food into liquid, it enters the small intestine.

Small intestine secretes enzymes that digest carbohydrate, fat and protein.  The cells lining intestine absorb nutrients into blood and lymph.

Then it goes to the large intestine, it reabsorbs water and minerals, passes waste and some water to rectum.

Rectum stores waste prior to elimination and Anus holds the rectum closed and it opens to allow elimination. (Crash course, 2012).

The Mechanical Aspect of Digestion

The mechanical digestion of food begins in the mouth where food is being chewed  by pieces and shreds food so that it can be swallowed smoothly into the esophagus.  Saliva is formed while chewing to add moist and soften rough or sharp food so that it can easily pass down into the esophagus.  Once food has been broken into small pieces and moistened, the food then travels into the stomach and intestines.  At the base of the esophagus, the sphincter squeezes the opening at the entrance to the stomach to narrow it and prevents the stomach’s contents from creeping back up the esophagus as the stomach contracts.  The food in the stomach is being grind, mixed thoroughly with acid and enzymes forming chyme.  At this point the nutrients such as starches and proteins have been split and uncoiled and the fat has been  separated. The pyloric valve part of the stomach  allows only a little bit of the time to excrete forcefully into the small intestine.  Within a few hours, the stomach is emptied by this powerful process.  The broken down food then contracts into the long journey of small intestine to move into the large intestines.   At this point, the water is reabsorbed and absorbed the minerals leaving only the undigested materials for excretion. The rectum stores the material waste to be excreted at intervals.

Human body’s digestive track performs a very complex process of digestion.   Starting from the mouth where digestion begins, an enzyme in saliva begins to break down the starch and digestion of fat rapidly.  The saliva helps maintain the health of the teeth by cleansing away the food particles that could decay in between the tooth and by neutralizing decay-promoting acids produced by bacteria in the mouth. 

The stomach is where the process of digestion begins.  Stomach releases a strong acid mixture of gastric juice, water, enzyme and hydrochloric acid.  The strong acid is needed to digest the protein consumed.  The range of pH demonstrates the different range from saliva being the weakly acidic to the stomach’s gastric juice being the strongest. (Sizer and Whitney, 2013).

The intestines are composed of small and large intestines. The small intestines do the digesting and absorbing the partially digested nutrients from the stomach. Hormonal messengers signal the gallbladder and release pancreatic juice to contract the right amount of bile into the intestines.   The chemical bonds that hold the large nutrients together on pancreatic and intestinal enzymes, smaller and smaller pieces are released into their surface.  A last minute breakdown performed by the enzymes are required before absorbing the nutrients.  All nutrients absorption is complete and remain in the tract by the time it gets to the large intestine.   All food consumed are broken down by enzymes into basic molecules that make them up. (Sizer and Whitney, 2013).