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Diagram of Digestive System

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What is a Digestive System?


The energy required for the daily processes and activities is provided by the food we eat. The digestive system enables us to use food from a variety of sources, including meat from animals and plant roots, as an energy source. We can run the process of digestion while performing other tasks, whether it's the ability to coordinate the chewing of the food without injuring our tongue and lips or the propulsion of the food from the stomach into the duodenum while releasing the appropriate enzymes.

Human Digestive System Diagram

Digestion is a fascinating and intricate process that transforms the food we put in our mouths into energy and waste products. This process happens in the gastrointestinal tracts. The gastrointestinal tract is a long and continuous tube that is present from the mouth to the anus. The meal is driven through the system, where it is transformed into useable particles by enzymes and hormones and absorbed along the way. The organs that help in digestion are the gall bladder, liver and pancreas. It takes around 30 hours for the food to travel from the mouth to the intestines.

Flow Chart of Human Digestive System

The Mouth

From the mouth, food enters our bodies. When we smell food, our salivary glands secrete saliva into our mouths. Chewing (mastication) is a breakdown of food into smaller particles that are more easily attacked by salivary enzymes once it enters the mouth. For cutting and grinding food, teeth are used. The tongue aids in the mixing of food with saliva and the tongue and roof of the mouth (soft palate) aid in the movement of food to the pharynx and oesophagus

Pharynx and Oesophagus

The mouth and oesophagus meet in the pharynx. From there it can take two paths that are:

  1. The incorrect path, which is down the windpipe into the lungs, or

  2. The correct path is into the oesophagus and eventually the stomach. Swallowing is a complex procedure that involves closing the windpipe (to protect our lungs) and moving food into the oesophagus. This process is primarily automatic (reflex), although we do have some control over it.

Food is carried to the stomach with the help of the oesophagus. The oesophagus contracts in a synchronized manner and help the food to move down to the stomach. Peristalsis is the name given to the movement of the oesophagus. The lower oesophagal sphincter is present in the stomach and it gets relaxed when the food reaches the stomach.


Acids and enzymes are produced from glands that line the stomach, continuing the food breakdown process.

  • Mucous

  • Digestive enzymes

  • Hydrochloric acid

Small Intestine

The small intestine is divided into three sections. The duodenum is the first part, where the food is further broken down. The jejunum and ileum, are the next two sections of the small intestine. The functions of the jejunum and ileum are the absorption of nutrients from processed food into the bloodstream through the intestine's walls.

The residual waste leaves the upper gastrointestinal tract (upper GI tract), which is made up of everything above the large intestine and travels into the large intestine or colon after passing through the small intestine (the beginning of the lower GI tract).

Large Intestine

The large intestines help in the absorption of water and minerals of the food. They also help in solidifying the wastes.

The large intestine (colon) is divided into four sections:

  1. Ascending colon,

  2. Transverse colon,

  3. Descending colon

  4. Sigmoid colon.


Although the pancreas is best known for producing insulin to regulate blood sugar (as part of the endocrine system — insulin is released directly into the bloodstream), it is also the primary producer of digestive enzymes as part of the exocrine system (the enzymes produced by the gland pass through a duct into the intestines).

Facts About the Digestive System

Disorders of the Human Digestive System

  1. The expulsion of stomach contents through the mouth is known as vomiting. Diarrhoea is a term used to describe an abnormally watery bowel movement. Dehydration is the result of prolonged diarrhoea.

  2. Constipation is a condition in which faeces become gripped within the rectum as a result of irregular bowel movements.

  3. Indigestion is stomach pain or discomfort that occurs when food is not fully digested, resulting in a sense of fullness. Inadequate enzyme secretion, food poisoning, anxiety, overeating, and eating spicy foods are the most common causes of indigestion.


Digestion is the process by which the food we eat is used to provide energy. There are various organs involved in digestion. They are the oesophagus, stomach, small and large intestines, pancreas and liver. There are different types of enzymes and salts that are secreted from these organs that aid in digestion. Each enzyme secreted from these organs is responsible for digesting different kinds of biomolecules.

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FAQs on Diagram of Digestive System

1. What is the purpose of the digestive system in humans?

Food and waste are mixed and moved through the body. Food is broken down into smaller particles during digestion. Nutritional absorption and waste excretion.

2. What are the two types of digestion?

Digestion is a type of catabolism, or substance breakdown, that involves two distinct processes: mechanical digestion and chemical digestion. Teeth help in the process of mechanical digestion by chewing the food and chemical digestion is done with the help of enzymes.

3. How does a human being digest food?

Food is moved through the GI system during digestion. The mouth helps in starting the process of digestion and then it ends in the small intestine. The food combines with digestive juices as it moves through the GI system, causing large food molecules to break down into smaller molecules.

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