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Human Digestive System: Diagram, Functions and Structure

Jul 6, 2022


Food plays an important role in the survival of all living organisms.  Feeding the human body with all the essential nutrients necessary for producing energy is required. The digestive system comprises multiple organs, forming a proper digestive tract that aids the human body’s breakdown and absorption of food.  It begins in the mouth as it is a long, twisted tube. It travels through the oesophagus, stomach, small intestine, large intestine, and anus.


The food is broken down into simpler micro and macronutrients such as carbohydrates, proteins, fats and various vitamins and minerals via the digestive system, which is absorbed by the bloodstream.  The absorption of nutrients helps the human body to produce energy which can be used in cell growth, development, and repair of various organs and tissues in the human body. 

All the unused human digestive system materials are disposed of from the human body in the form of excretion.  Along with these, the human digestive system consists of multiple other organs, such as the pancreas, gallbladder and liver, which secrete essential juices playing a crucial role in the functioning of the entire system.  


What is the Human Digestive System?

The human digestive system is a type of digestive system involved in the human body to break down food.  The human digestive system consists of a digestive tract or the chain of organs and structures through which liquids and foods pass throughout their breakdown process so that they can be easily absorbed into the bloodstream of the human body.  The human digestive system also includes the structures that help eliminate and move the wastes during the evacuation process, as well as certain organs that secrete essential juices, which can help digestion.

Curiously EnoughThe digestive tract runs from the mouth to the anus.  It resembles a lengthy muscular tubing, up to 10 metres in length, with all helping digestive organs joined along the tube.

How does the Human Digestive System Work?

The digestive tract runs from the mouth to the anus. It starts from the floor of the mouth, or oral cavity, using teeth for chewing and grinding food and a  tongue for kneading the chewed food and mixing it with saliva secreted by the salivary glands; the throat, or pharynx; the oesophagus; the stomach; the small intestine, which includes the duodenum, ileum and jejunum; and the large intestine, which includes the cecum, a closed-end sac linking with the ileum, the ascending colon, transverse colon.


Various glands provide essential digestive juices in the human digestive system, such as gastric glands in the stomach lining, the pancreas, the liver and its related organs, gallbladder and bile ducts.  These digestive system organs and glands help in the chemical and physical breakdown of ingested food, as well as the subsequent removal of non – digestible wastes.

Did You Know?The large intestine contains a significant pool of germs such as bacteria.  These bacteria are essential for proper digestion.  The specific types of bacteria differ from individual to person.  Other factors affecting digestive tract bacteria include the individual’s geographic location, health issues, and drugs.

Human Digestive System Diagram

Human Digestive System


Digestive System Functions and Structure 

Mouth and Oesophagus

The digestive process starts in the mouth. The teeth grind the food into very little particles when a person eats. The salivary glands in the cheeks lining and under the tongue secrete saliva, which helps coat the food, making it simpler to chew and swallow. The function of saliva is to make it easier for individuals to swallow the food crushed up by the teeth and lubricated with saliva. Saliva also contains a particular chemical known as an enzyme, which begins the breakdown of carbs into sugars.

Once the food is swallowed, the muscular contraction and relaxation of the oesophagus push the food ball into the stomach bag. The function of the oesophagus, the muscular tube, is to transport the swallowed food from the mouth to the stomach bag. A ring of muscle at the oesophagus flexes to let food enter the abdomen and tightens to restrict stomach contents from flowing up the oesophagus.


The food enters the stomach via a sphincter, a tiny muscle ring. The gastric juices secreted by the stomach lining combine with the swallowed food here. The stomach is a muscular pouch that churns the food physically and chemically to help break it down into simpler forms. The meal is subsequently forced through a second sphincter into the initial section of the small intestine, known as the duodenum.

Did You Know?The gastric juice (enzymes accompanied by hydrochloric acid) is produced by the stomach wall. It breaks down proteins. The stomach churns and mixes food with gastric fluid to generate chyme, a dense, soupy fluid.
Small Intestine

The bile juice secreted from the gallbladder and enzymes in pancreatic digestive secretions enters the upper region of the small intestine and aid in the breakdown of protein into amino acids and fat into lipids or fatty acids. The small intestinal wall absorbs all the important micro and macronutrients such as carbohydrates, vitamins, and minerals from these breakdown food granules.

Did You Know?The small intestine is called “small” because it’s just around 3.5 cm wide and is roughly around 5m long, so there’s plenty of room for absorption of food. The small intestine is responsible for most of the biochemical digestion of proteins, lipids, and carbohydrates.

Food is subsequently pressed into the jejunum and ileum, the lowest sections of the small intestine. The ileum is coated with thousands of finger-like projections known as villi. Its function is to absorb the nutrients from the food granules. Each villus is linked to a network of capillaries. In this way, the nutrients enter the bloodstream of the human body. 

Large Intestine

The function of the large intestine is to absorb minerals, water, salts, and vitamins. Here the undigested fibre is combined with bacteria and mucus, which partially break down the micronutrients, nourishing the large intestine’s cell wall. It helps in maintaining the large intestine healthy. Faeces are generated and stored in the last section of the large intestine (the rectum) before exiting the body via the anus.

Curiously EnoughOnce all the micro and macronutrients have been absorbed, the excrement (waste) is transferred to the large intestine, also known as the gut or bowel. The waste (faeces) is kept in the rectum while the water is evacuated. This waste is expelled from the body via the anus.

What are some common human digestive system constraints?

Gastroesophageal reflux 

Gastro-oesophageal reflux (GORD) develops when the acid generated in the stomach flows up the oesophagus pipe from the stomach. Giving an individual a burning sensation in their throat and chest.


Diverticulitis is characterised by infection or inflammation of aberrant pouches in the lower intestine. It might produce mild to severe abdominal pain on the lower left side of the stomach.


Haemorrhoids are itchy or painful lumps around the anus region, causing bleeding in the sensitive areas. These swollen blood vessels are present in the lumps. Individuals must always seek medical attention if they see blood while using toilet paper or on the toilet.

Stomach Ulcers

Stomach ulcers are related to the bacterium Helicobacter pylori. According to statistical reports, every four out of ten people are seen affected by stomach ulcers. In certain people, they can induce long-term, moderate inflammation of the stomach lining. It is still unclear why stomach ulcers occur in some people but not others.


Students can aid their human digestive system by drinking plenty of water and eating a fibre-rich diet. High-fibre foods, including vegetables, fruits, and whole-grain foods (barley, wheat), help excrement flow through the human digestive system more easily.

The digestive system organs play in your body. Without it, humans wouldn’t be able to obtain the nutrients they need to grow and remain healthy. Thus, the next time individuals have their meal, they will know exactly where their food is going – from starting to ending!

Frequently Asked Questions

1. What is the liver and pancreas function in the human digestive system?

 The liver serves a variety of functions in the body, including:

  • Utilising bile juice deposited in the gallbladder to break down complex fats into lipids.
  • Absorption of carbohydrates and proteins.
  • Filtering and processing all the body’s impurities, chemicals, and toxins.
  • Synthesising glucose from other substances like amino acids and lactate to meet the short-term energy requirements in the body.

The pancreas is one of the biggest glands in the human body system. It releases a hormone called insulin in addition to its digestive juices. Insulin aids in the regulation of blood sugar levels. Diabetes is a disease caused by insulin manufacturing issues.

2. How can humans keep their digestive system in good shape?

A.Suppose an individual has a certain medical condition, it’s advisable to always consult with the doctor about what they should do and consume to be healthy and control their condition. The following are some techniques to keep the human digestive system in good shape:

  • Water facilitates the passage of food to the digestive system. Constipation is frequently caused by a lack of fluids in the human body, resulting in dehydration.
  • Fibre is a good source of digestion and keeps bowel movements regular. Thus every individual should try to include both insoluble and soluble fibre in their diet.
  • Consume a well-balanced diet, including multiple servings of fruits and vegetables daily. Select whole grains over refined starches.

3. Name some common human digestive system disorders.

A.Here are some of the most prevalent human digestive system issues:

  • Colitis is intestinal inflammation.
  • Diverticulitis: Inflammation on the lining of the small intestine.
  • Gastroenteritis: Infection that produces nausea and vomiting.
  • Heartburn: It occurs when stomach contents reflux into the oesophagus.
  • Stomach or duodenum ulcer: It is a hole in the mucus layer lining of the stomach or duodenum.
Human Digestive System


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