The Digestive (Gastrointestinal) System

Providing Nutritional Support and Waste Removal for the Body

Jun 7, 2009

The digestive system is one of twelve organized body systems. Its major functions are to provide nutritional support and a means of removing solid waste from the body.

The digestive system is one long continuous tube that begins in the mouth and ends with the anus. The digestion of a meal takes several hours, utilizes both mechanically, and chemically processes to transform it into usable components.

Components

In addition, three ancillary organs provide a significant role in assisting the chemical break down of food by secreting important enzymes directly into the first segment of the small intestine:

Process

The process of digestion actually begins in the mouth with the production of salivary enzymes, which chemically break down food into a substance referred to as a bolus. After the bolus is swallowed, wavelike contractions, (peristalsis) moves it through the system by first entering the pharynx (throat).

The pharynx houses two organs, the esophagus (food pipe) and the trachea (windpipe). The bolus maintains its course down the esophagus by means of a small flap of tissue called the epiglottis that prevents the bolus from inadvertently entering the trachea and subsequently the lungs.

The bolus enters the stomach from the esophagus via the cardiac sphincter. The unfolding activities within the stomach further process the bolus. First contractions mechanically separate the bolus while enzymes found in the gastric (stomach) juices chemically break down the bolus, into a nutrient rich mixture called chyme. Finally, the stomach squirts chyme directly into the first segment of the small intestine via the pyloric sphincter.

The Intestines

Combined, the small and large intestines are called the bowels. Although many also refer to them as the colon, technically the term colon is reserved for the large intestine only.

Small Intestine

The small intestine is approximately twenty feet of coiled tubing and is divided into three segments or loops:

Nutrients are further broken down in the small intestine with the help of enzymes secreted directly into the duodenum by the pancreas, liver, and gall bladder. As Chyme slowly moves down and encounters the walls of the small intestinal tract, the nutrtional contents are absorbed, leaving only digestive waste.

Large Intestine

Divided into seven segments or loops, the large intestine is shorter and wider than the small intestine:

Removal of Waste

The waste product, called stool or feces, transitions from a liquid material to a soft and solid formed mass as it slowly moves through the colon. If the stool moves through the sequence too quickly then water cannot effectively be absorbed resulting in very loose stool or even diarrhea.

The rectum is a holding pouch; nerves in the area trigger the brain when the pouch is ready to empty. This immediately sends a stimulus to the individual as an urge to defecate.

The Urge

When a person disregards the urge stimulus on a regular basis, the brain will adapt, resulting in subtle to non-existenet sensations. For many, the urge stimulus acts as a reminder, without it, many forget when they last had a bowel movement. Moreover, the longer the stool remains in the colon the harder it will become, making defecation very difficult and uncomfortable.

Quantifying Bowel Movements

It is difficult to quantify how many bowel movements a person should have because individuals vary. According to the Mayo Clinic, three bowel movements per week is normal, while the Harvard Health Report, 2007, gives a range of three bowel movements per day to three per week, as normal.

Most gastroenterologists are less concerned with the number of bowel movements, and more concerned with the problems caused by a sluggish system. For example, one person might only have two bowel movements per week and exhibit no difficulties while another person may exhibit constipation, if they don't have a daily bowel movement.

In conclusion, the digestive system is important because it is responsible for converting ordinary foods into substances that the body can utilize nutritionally. Disruptions to the digestive process are often a result of either mechanically or chemically problems. Upsets much be attended to immediately to prevent irreversible damage.

The copyright of the article The Digestive (Gastrointestinal) System in Health Field is owned by Linda Mundorff. Permission to republish The Digestive (Gastrointestinal) System in print or online must be granted by the author in writing.