Human Digestive System

Table of Contents

What Is Digestive System

Parts Of The Digestive System

Digestion Process

Disorders Of The Digestive System

Functions Of The Digestive System

Human Digestive System

Human Digestive System Diagram showing different parts of the digestive system

What is Digestive System?

A human digestive system is a group of organs working together in converting food into energy and basic nutrients required for the body. It is made up of the gastrointestinal tract, also called a digestive tract along with liver, pancreas, and gallbladder which constitute the parts of the digestive system. The hollow organs that make up the gastrointestinal tract (GI tract) include the mouth, stomach, esophagus, small intestine, and large intestine that contains rectum and anus.

Human Digestive System and Nutrition involve the intake of food by an organism and its utilization for energy. This is a vital process which helps living beings to obtain their energy from various sources. The food which we eat undergoes a lot of processing before the nutrients present in them are utilized to generate energy. This processing is known as digestion. Humans and other animals have specialized organs and system for this process.

The digestion process involves the alimentary canal along with various accessory organs and organ systems. In humans, the process is quite simple due to our monogastric nature. This means that we have a one-chambered stomach, unlike other animals such as cows, which have four chambers.

Some parts of nervous and circulatory systems also play a major role in the digestion process. A combination of nerves, bacteria, hormones, blood, and organs of the digestive system complete the task of digestion that a person consumes in a day.

Also Read: Alimentary Canal

Parts of the Digestive System

The digestive system of the human body comprises of a  group of organs that work together in converting food into energy and other basic nutrients to power the body. The food we take in is digested and utilized by our body and the unused parts of the food are defecated.

The human digestive system is the sum of the gastrointestinal tract (GIT; also called alimentary canal) and accessory organs (tongue, liver, pancreas, etc). These two parts together help in digestion.

The alimentary canal is the long tube through which the food that we eat is passed. It begins at the mouth (buccal or oral cavity), passes through the pharynx, esophagus or food pipe, stomach, small intestines, large intestines, rectum and finally ends at the anus. The food particles get digested gradually as they travel through various compartments of the alimentary canal.

Accessory organs are organs which participate in the digestion process but are not actually a part of GIT. They stimulate the digestion by releasing certain enzymes that help in breaking down the food

Let us have a detailed look at the different parts of the digestive system along with its functions:

Mouth

Food starts its journey from the mouth or the oral cavity. There are many other organs that contribute to the digestion process including teeth, salivary glands, and tongue. Teeth are designed to grind food particles into small pieces and are moistened with saliva before the tongue pushes the food into the pharynx.

Pharynx

A fibromuscular y shaped tube attached to the terminal end of the mouth. It is mainly involved in the passage of chewed/crushed food from the mouth through the esophagus. It also has a major part in the respiratory system, as air travels through the pharynx from the nasal cavity on its way to the lungs.

Esophagus

This is a muscular tube that connects the pharynx which is a part of an upper section of the gastrointestinal tract. It supplies swallowed food along with its length.

Stomach

It serves as a muscular bag which is situated towards the left side of the abdominal cavity, beneath the diaphragm. This vital organ acts as a storage for the food and provides enough time to digest meals. The stomach also produces digestive enzymes and hydrochloric acid that maintains the process of digestion.

  • Mucous: It is an aqueous secretion produced by the mucous membranes. It functions by protecting the stomach lining and gastric pits from the acid which is produced by the glands to destroy the bacteria that entered along with the food particles.

  • Digestive enzymes: They are the group of enzymes which functions by breaking down polymeric macromolecules like biopolymers into their smaller and simpler substances.

  • Hydrochloric acid: It is the digestive fluid formed by the stomach during the process of digestion. It functions by destroying harmful microorganisms present in the food particles.

Small Intestine

The small intestine is a thin, long tube of about 10 feet long and a part of the lower gastrointestinal tract. It is present just behind the stomach and acquires a maximum area of the abdominal cavity. The complete small intestine is coiled and inner surface consists of folds and ridges.

Large Intestine

This is a thick, long tube measuring around 5 feet in length. It is present just beneath to the stomach and wraps over the superior and lateral edges of the small intestine. It absorbs water and consists of bacteria (symbiotic) that support in the break down of wastes to fetch small nutrients.

Also Read: Large Intestine

Rectum

Waste products are passed into the end of the large intestine called the rectum and eliminated out of the body as a solid matter called stool. It is stored in the rectum as semi-solid faeces which later exits from the body through the anal canal through the process of defecation.

Accessory Organs

Pancreas

It is a larger gland present just inferior to the stomach. It is short with its head connected to the duodenum and tail pointing towards the left part of the abdominal cavity. The pancreas releases digestive enzymes to complete the process of chemical digestion.

Liver

The liver is a roughly triangular, reddish brown accessory organ of the digestive system located to the right of the stomach. It produces bile, which helps in the digestion of fat in the small intestine. The bile is stored and recycled in the gallbladder. It is a small, pear-shaped organ which is located just next to the liver.

Digestion Process

The process of digestion begins from the mouth and ends in the small intestine – the large intestines’ main function is to absorb the remaining water from the undigested food and enable bacterial fermentation of materials that can no longer be digested.

The alimentary canal or the gastrointestinal tract is a series of hollow organs and tubes that begins from the mouth cavity and continues into the pharynx, through the stomach, small intestines, large intestines, and finally ending at the anus. Food particles get digested gradually as they travel through various compartments of the gastrointestinal tract.

The digestion process takes place in the following steps.

Ingestion

The very first step involves mastication (chewing). The salivary glands, along with the tongue helps to moisten and lubricate food, before being pushed down into the food pipe.

Mixing and movement

It involves the process of lubricating and manipulating food and pushing it down the food through the food pipe (using peristalsis), and into the stomach.

Secretion

The stomach, small intestine, liver, and pancreas secrete enzymes and acids to aid the process of digestion. It functions by breaking down food particles into simple components and easily absorbable components.

Digestion

The process of converting complex food particles into simpler substances in the presence of enzymes and acids secreted by different digestive organs.

Absorption

This process begins in the small intestine where most of the nutrients and minerals are absorbed. The excess water in the indigestible matter is absorbed by the large intestines.

Excretion

The process of removing indigestible substances and waste by-products from the body through the process of defecation.

In a nutshell, the digestion process consists of the six following steps:

Ingestion Mixing and Movement ⇒ Secretion ⇒ Digestion Absorption Excretion

Disorders of the Digestive System

  1. Jaundice: In this. The liver gets affected, skin and eyes turn yellow due to the deposit of bile pigment.
  1. Vomiting: It is the ejection of stomach contents through the mouth and controlled by the centre in the medulla oblongata.
  1. Diarrhoea: It is the abnormal bowel movement and the faecal discharge with more liquidity, which leads to dehydration.
  1. Constipation: A condition in which the faeces are clutched within the rectum due to an irregular bowel movement.
  1. Indigestion: A pain or discomfort in the stomach which is caused when food is not digested properly resulting in the feeling of fullness.  Indigestion is mainly caused due to inadequate enzyme secretion, food poisoning, anxiety, overeating and eating spicy foods.

Functions of the Digestive System

Digestion and absorption are the two main functions of the digestive system.

Digestion is necessary for breaking down food particles into nutrients that are used by the body as an energy source, cell repair, and growth.

Food and drink need to be converted into smaller molecules of nutrients before it is absorbed by the blood and carried to the cells throughout the body. The body breaks the nutrients present in the drinks and food into carbohydrates, vitamins, fats, and proteins.

Also Read: Mouth and Buccal Cavity

To learn more about the human digestive system and related topics such as parts of the digestive system, digestion process, disorders of the digestive system, and functions of the digestive system, keep visiting BYJU’S Biology or download BYJU’S app for further reference.

Important Questions

1. Deduce the function of the human digestive system.

The digestive system consists of the alimentary canal and the accessory organs. Their main function is to break down the ingested food into its components and produce vital nutrients and energy required to sustain life.

2. What are accessory organs?

Accessory organs are organs which are not part of the digestive system, however, they aid in the digestion process by performing many secondary functions. The main accessory organs of the digestive system are the tongue, liver, pancreas and gall bladder.

3. Outline the process of digestion, step by step.

The process of digestion involves the following steps, namely:

  • Ingestion
  • Mixing and Movement
  • Secretion
  • Digestion
  • Absorption
  • Excretion

4. List out the parts of the digestive system

  • Mouth & Buccal Cavity
  • Pharynx
  • Oesophagus
  • Stomach
  • Small Intestine
  • Rectum

5. Explain the role of the tongue as an accessory Organ

The tongue is not a part of the digestive system but it provides support functions such as moving and manipulating the food within the buccal cavity. Furthermore, moistening food also helps to swallow and pass through the oesophagus without much resistance.

Practise This Question

What will happen if we do not clean our teeth regularly?

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