Function of Digestive Organs

Function of Digestive Organs

The human digestive system supports essential functions of life, often through nutrition to fuel the body systems and the building blocks of the body. It contains a series of various organs across a long tract extending from the mouth to the rectum.


Digestion begins at the mouth with the mechanical breakdown of foods into small chunks known as bolus. The chewing process mixes food with the saliva and marks the onset of the chemical digestion of starch due to the amylase. Its purpose is to moisten the food for lubrication and maximize the surface area to allow the further breakdown of complex food materials into beneficial nutrients required by the body (Welcome, 2019).


After swallowing the bolus, it travels through the esophagus to the stomach, where it mixes and churns bolus with gastric juices. The content consists of a semi-fluid mixture of partly digested food and digestive juices known as chyme. Gastric juices also stimulate the digestion of proteins and the absorption of fat-soluble nutrients (Khan Academy, 2019). Because of the high acidity levels, the stomach is covered with a layer of mucous to protect gastric walls against acidic content.

Small Intestine

The stomach then releases the chyme into the small intestine. Here, the chyme will travel first in the duodenum, then the jejunum, and lastly into the ileum. In the duodenum, pancreatic juices act on fat, carbohydrates, and proteins. Bile from the gall bladder facilitates further breakdown and absorption of fats (Khan Academy, 2019). The movement of food materials in the small intestine is often slower to optimize nutrient digestion and nutrient absorption. This component also contains villi, finger-like projections, which provide a large surface area for nutrient absorption. Major organs that support small intestinal digestion include the pancreas, gallbladder, and liver (Khan Academy, 2019). Pancreatic juices contain bicarbonate content to neutralize gastric acids from within the chyme, thus creating optimal conditions for enzymatic functions.

Large intestine

Once essential nutrients are absorbed, the small intestine release food residuals from the colon or large intestine, further breakdown and absorption of remnant water, vitamins from enteric bacteria, and electrolytes. The large intestine provides transient storage of residuals to allow the accumulation of waste materials before propelling them toward the rectum for elimination as feces (Molnar & Gair, 2015 ). It also secretes mucus to facilitate the passage and elimination of fecal matter.


Peristalsis encompasses sequential and interchanging waves of relaxation and contraction that propel the food along the digestive tract. The waves begin in the esophagus and facilitate the mixing and churning of food content in the stomach. The process is very powerful and automatic, thus ensuring the continuous movement of food along the digestive tract. The motion also includes the movement of enzymatic juices through the ducts (Welcome, 2019). This is evident in the release of bile from the gallbladder into the small intestine.

Bacterial contaminants can fasten peristalsis as the body attempts to expel contaminated content from the stomach. An example of such a disease is irritable bowel movement. Another condition that can slow peristalsis is intestinal obstruction. It develops when a blockage prevents food from passing through the small intestine or colon. A possible reason for the condition might be attributable to the lack of sufficient fiber content in the diet. Constipation can also signify intestinal blockage or slow peristalsis movements. Laxatives are mostly used to quicken the peristalsis and manage or prevent constipation.


Khan Academy. (2019). The digestive system | Crash Course biology| Khan Academy. [YouTube Video].