Human Digestive System

BiologyHuman biology


People's digestive system is made up of their teeth and tongue as well as the oesophagus, stomach, and small intestine (colon). There are four major organs involved in food digestion and absorption. Food travels through all these organs before it is expelled from the body as faeces via the large and small intestine (poop).

Parts of the Human Digestive System

To understand how your digestive system works, it helps to know what each part does−


This organ receives food from the outside world through eating and drinking. Chewing breaks down large pieces of food into smaller ones that are easier for your body to digest. Saliva produced by glands in your mouth helps lubricate food so it can be swallowed more easily. Teeth grind up food into even smaller bits so it can be absorbed into your bloodstream through your intestines. Your tongue pushes food toward your throat, where muscles help propel it down your esophagus (food pipe).


The oesophagus receives food from the mouth via the pharynx (throat). Peristalsis is the mechanism by which food is transported from the pharynx to the stomach via the oesophagus (waves of muscular contraction).


Food travels through the oesophagus from the throat to the stomach. It has two sphincters (valves) preventing food from travelling back into your throat. One sphincter is voluntary (conscious), and one is involuntary (unconscious). When you swallow, your voluntary sphincter opens so you can swallow your food without choking or gagging on it. Your involuntary sphincter stays closed until you swallow again, so you don't choke on what's already in your mouth!


The stomach stores and mixes food with enzymes, acids and mucus (which protect it from its own acid). Then this mixture moves into the small intestine, where most digestion occurs.

Small Intestine

The small intestine is about 20 feet long and consists of three sections− duodenum, jejunum and ileum. This area absorbs nutrients from digested foods through cell walls, which produce an enzyme called lactase that helps break down milk sugar (lactose).

Large Intestine

The large intestine absorbs water from digested food before it leaves through the anus as bowel movements.


The rectum is the last part of your digestive system. It sits between your colon (large intestine) and anus (exit point). When you have to go to the bathroom, muscles in your rectum push stool toward your anus.

Accessory Organs

The accessory organs include−

Stomach− This organ is an empty sack about 10 inches long that stores food until it can be digested. It also secretes chemicals that help break down food into smaller particles so they can easily pass through your small intestine.

Pancreas− This organ makes enzymes that digest carbohydrates (starches), fats and proteins in food; it also makes insulin, which helps regulate blood sugar levels by moving glucose into cells for energy production or storage as fat when needed.

Liver− This organ produces bile that mixes with fats to help absorb them from the small intestine so they can be used as energy sources by body tissues.

Digestion Process

The digestive system is a complex system of organs, glands and other structures that break down food into the nutrients your body can use. It includes the mouth, oesophagus, stomach and intestines.

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The digestive tract is responsible for absorbing nutrients from food. The process begins in the mouth when you chew food to make it easier to swallow and digest. Next, the food travels through your oesophagus and into your stomach, where it's mixed with enzymes from the pancreas and liver to break down proteins, fats and carbohydrates by churning them into smaller pieces. Finally, the partially digested material passes from your stomach into your small intestine through an opening called the pylorus.

There, enzymes from the pancreas continue to digest carbohydrates while bile from the gallbladder adds fat-digesting enzymes. After passing through your small intestine, undigested matter makes its way into your large intestine (colon) where water is extracted from it before ending up in the rectum (end of the digestive tract). The colon wall absorbs any remaining water before waste leaves the body through excretion or defecation.

Disorders of the Human Digestive System

Disorders such as celiac disease can affect all parts of the digestive tract. Other disorders affect only specific organs in the digestive system. For example, peptic ulcer disease affects only the stomach and duodenum (the upper part of your small intestine).

Digestive disorders can cause symptoms such as abdominal pain or bloat. They can also cause vomiting or weight loss. Digestive disorders may require treatment by a doctor specialising in digestive diseases (gastroenterologists) or other medical specialists.

The most common disorders of the digestive system include−

  • Rheumatoid arthritis (GERD). Acid reflux disease (GERD) is a medical ailment. Stomach contents back up into the oesophagus due to this disorder. As well as heartburn, some people have chest pain when they have this condition.

  • Gastroesophageal reflux disease (GERD). This condition causes stomach contents to back up into your oesophagus. It's often called heartburn because it may also cause chest pain.

  • Oesophagal cancer. Cancer in this area of your throat often affects older adults who have smoked or drank alcohol excessively for many years and those who've had acid reflux disease for many years without treatment. Surgery is usually required to remove tumors and lymph nodes in this area.

Functions of the Human Digestive System

The digestive system comprises the mouth, oesophagus, stomach and small and large intestines. It is what digests food and converts it into usable nutrients that your body can absorb.

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Digestive enzymes are released into the bloodstream after food is eaten and salivated. Even before you've swallowed the starch, an enzyme called amylase in your saliva breaks it down.

When you swallow, the food goes down your oesophagus into your stomach, further broken down by acid and gastric enzymes. The pyloric sphincter controls when food passes from the stomach into the small intestine.

Once food has moved through the small intestine, it enters the large intestine, where bacteria break down any remaining fibre. The large intestine absorbs water from fecal matter before feces pass out as bowel movements from your rectum.


The human digestive system is an amazing system that breaks down food into nutrients that the body needs to survive. The system is made up of many different organs, each with a specific purpose. The system is able to extract nutrients from food and eliminate waste. The digestive system is a vital part of the human body and is necessary for good health.


1. What is the human digestive system?

The human digestive system is a complex arrangement of organs that work together to break down food, absorb nutrients and eliminate waste.

2. How does the digestive system work?

The digestive system breaks down food into small particles with enzymes produced by the pancreas and liver. These particles are then absorbed into the blood through the intestinal wall. The cells lining the intestines absorb water from digested food, which is why stool is usually solid or semisolid.

3. What are some common problems associated with the digestive system?

Common digestive system problems include irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), colitis and Crohn's disease. Other issues include chronic constipation, diarrhoea or even an inability to eat solid foods due to mouth sores or anorexia nervosa.

4. How long does it take for food to pass through my entire digestive system?

It takes about 24 hours for food to pass through your entire digestive system from start to finish (mouth to anus). The length of time depends on what you eat on any given day and how active you are afterwards; some foods may require more time than others do − such as high-fibre foods or certain types of meat − while others might move more quickly through your body depending on how fast your metabolism works.

5. What is the function of the Mouth?

The mouth has several functions− It can chew and crush food before it goes to the stomach. It also plays an important role in taste perception by receiving information from food through different types of taste buds present on its tongue and mouth walls.

Updated on 13-Oct-2022 11:19:47