Gastrointestinal System – Intro, Functions, Movements & Organs Associated

Gastrointestinal System - Intro, Functions, Movements & Organs Associated

The gastrointestinal system is also known as the digestive system. It is a collective name of the alimentary canal and accessory organs.

The alimentary canal forms a continuous tube that is open to the outside environment at both ends.

The organs of the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

The overall process of digestion and absorption occurs in the alimentary canal.

Accessory structures include the teeth, tongue (in the oral cavity), salivary glands, liver, gallbladder, and pancreas.

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Functions of the Digestive System


  • The oral cavity allows food to enter the digestive tract and have mastication (chewing) occurs which resulting food bolus is swallowed.


  • Mechanical digestion – The muscular movement of the digestive tract (mainly in the oral cavity and stomach) physically break down the food into smaller particles.
  • Chemical digestion – The hydrolysis reactions aided by enzymes mainly in the stomach and small intestine. Chemically break down food particles into nutrient molecules, small enough to be absorbed.


  • The enzymes and digestive fluids secreted by the digestive tract and its accessory organs facilitate chemical digestion.


  • At the end of the passage, the products or nutrients of chemical digestion From the digestive tract enters or absorb into blood or lymph to distribution to tissue cells.


  • The undigested material will be released through the rectum and anus by defecation.

Muscular movement involves the gastrointestinal tract / digestive system:-


  • It is a wavelike movement that occurs from the oropharynx to the rectum which allowing the gastrointestinal tract to push food particles toward the anus.


  • Mixing is a motion in the oral cavity and stomach that allows the gastrointestinal tract to repeatedly break down food into smaller particles using mechanical digestion.


  • In the regions of the small intestine contracting and relaxing occurs independently that allowing the small intestine to digest and absorb more efficiently.

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Organs of the gastrointestinal system or digestive system:-

All digestive organs play integral roles in the life-sustaining process of digestion.

The easiest way to understand the digestive system is to divide its organs into two main categories. The first group is the organs that make up the alimentary canal.

Accessory digestive organs comprise the second group and are critical for orchestrating the breakdown of food and the assimilation of its nutrients into the body.

Accessory digestive organs, despite their name, are critical to the function of the digestive system.

Alimentary Canal Organs

It is also known as the gastrointestinal tract or gut. Ailment means “to nourish”.

The alimentary canal is the one-way tube about 7.62 meters (25 feet) in length during life and closer to 10.67 meters (35 feet) in length when measured after death, once smooth muscle tone is lost.

The main function of the organs of the alimentary canal is to nourish the body. The main parts of the alimentary canal are the following :

  1. Mouth or buccal cavity with tongue
  2. Oropharynx
  3. Esophagus
  4. Stomach
  5. Small intestine
  6. Large intestine

There are some other part in Small intestine & Large intestine

Small Intestine: the part of the intestine that runs between the stomach and the large intestine:

  1. Duodenum
  2. Jejunum & ileum

Large Intestine: The last part of the intestine which is wider and shorter than the small intestine, which consists of the cecum, colon, and rectum, which absorbs water from the material left over from digestion and prepares the faces for release from the body.

– Parts of the large intestine

  1. Caecum
  2. Ascending colon
  3. Transverse colon
  4. Descending colon
  5. Sigmoid colon
  6. Rectum
  7. Anal canal

Accessory organs of the digestive system

Various secretions are poured into the alimentary tract, some by glands in the lining membrane of the organs,e.g. gastric juice secreted by glands in the lining of the stomach, and some by glands situated outside the tract.

The latter are the accessory organs of digestion and their secretions pass through ducts to enter the tract. They consist of:

  1. 3 pairs of salivary glands
  2. pancreas
  3. liver and the biliary tract.

The organs and glands are linked physiologically as well as anatomically in that digestion and absorption occur in stages, each stage being dependent upon the previous stage or stages.

# The digestive system cannot work independently, it’s functions are cooperative with other body functions. So the contribution of another body system to the digestive system are listed below:-

Contribution of Other Body Systems to the Digestive System
Body system Benefits received by the digestive system
Cardiovascular Blood supplies digestive organs with oxygen and processed nutrients
Endocrine Endocrine hormones help regulate secretion in digestive glands and accessory organs
Integumentary The skin helps protect digestive organs and synthesizes vitamin D for calcium absorption
Lymphatic Mucosa-associated lymphoid tissue and other lymphatic tissue defend against the entry of pathogens; lacteals absorb lipids; and lymphatic vessels transport lipids to the bloodstream
Muscular Skeletal muscles support and protect abdominal organs
Nervous Sensory and motor neurons help regulate secretions and muscle contractions in the digestive tract
Respiratory Respiratory organs provide oxygen and remove carbon dioxide
Skeletal Bones help protect and support digestive organs
Urinary Kidneys convert vitamin D into its active form, allowing calcium absorption in the small intestine

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