Where Do We Digest Food?

Digestion of food in humans occurs in the gastrointestinal tract – a series of hollow organs (mouth, esophagus, stomach, large intestine and small) are connected to form a long tube of about 24 feet long that extends from the mouth to the anus. Also known as the GI tract, gastrointestinal tract, digestive tract, or gut. Above the large intestine, the digestive system is sometimes called the upper gastrointestinal tract, while everything below is the lower gastrointestinal tract. The tract has muscular walls that propel food along the tube (a process called peristalsis) decomposition and mixing it with digestive juices for optimum absorption.

The functions of the digestive system

The gastrointestinal tract has four main functions. It eats the food we eat, but breaks down into simple chemical components for energy and nutritional purposes to extract nutrients from the same (eg, macronutrients such as carbohydrates, fats, protein and micronutrients such as vitamins and minerals) and, finally, that expels the waste of food.

How does the food passes through the digestive tract

During feeding, the food passes from the mouth into the esophagus, then into the stomach from entering the small intestine (including   duodenum , jejunum and ileum). Most if not all nutrients are absorbed in the stomach and small intestine. Water and waste products then pass into the large intestine comprising (cecum, colon and rectum), from where it exits the body through the anus. Other organs that contribute to healthy digestion include the liver, pancreas and gallbladder. A significant number of gastrointestinal hormones and digestive enzymes help regulate digestion, especially in the upper gastrointestinal tract. The movement of food through the digestive system main pipe (esophagus, small intestine and large intestine) is maintained by a series of muscle contractions called peristalsis. Several muscular valves control the passage of food and prevent it from moving backward. On average, it takes about 40-45 hours for food waste to pass through the digestive tract.

Digestion begins in the mouth – the beginning of the digestive tract. Smells of food make the salivary glands in the mouth to secrete saliva (mouth water), so even before starting to eat our digestive system is prepared and ready for action! Saliva contains antibacterial compounds and various enzymes to help break the food molecules. It also softens the food – which allows the tongue to shape a bowling ball down. The tongue, teeth and saliva work together to start the digestion and swallowing. Teeth cut and grind food, breaking food into pieces small enough to be digested and increasing the surface on the digestive enzymes in saliva can act. For more information, see Guide to digestion in the mouth.

The pharynx and esophagus,

Food is swallowed and then into the pharynx, or throat. When we swallow, the passages to the lungs (trachea) and the nasal cavity are automatically closed, and the food enters the esophagus – a muscular tube that extends from the pharynx to the stomach. The food is pushed through the esophagus into the stomach through muscular contractions called peristalsis. In the lower esophagus, just before the opening to the stomach is a ring-shaped muscle called the lower esophageal sphincter (LES). This produces a relaxation (opening) so that in the stomach and then tightens food (closed) to prevent regurgitation. If the malfunction of the lower esophageal sphincter and allows the food in the stomach to re-enter the esophagus, can cause a condition called gastroesophageal reflux disease (GERD), characterized by heartburn and regurgitation. For more information, see Guide to digestion in the esophagus.


A large bag with strong muscular walls, the stomach acts as a temporary storage station and food for the world to chew and swallow food. Has the ability to expand or contract depending on the amount of food it contains. The stomach helps digestion in two ways. Its muscular walls high turnover of food chyme – a semi-liquid mixture like porridge – while within the walls glands secrete gastric juice – a mixture of hydrochloric acid and various digestive enzymes – which helps to digest food as proteins, fats, carbohydrates and a little alcohol. To prevent the stomach to digest it (!) The walls are covered with a membrane called mucosa that secretes a sticky substance called protective mucosa. The liquids pass through the stomach within minutes, while solids can remain in the stomach for up to five hours. Chyme leaves the stomach slowly and enters the small intestine. For more information, see Guide to digestion in the stomach.

The small intestine

Approximately 17 feet long, the small intestine is a coiled tube made up of three sections – the  duodenum , jejunum and ileum. As the semi-digested (chyme) enters the  duodenum  from the stomach,  duodenum  lining releases hormones that stimulate intestinal gallbladder and pancreas to release special digestive juices (bile and pancreatic juice), which help break down food molecules more in the chyme. It is in the small intestine that most nutrients are digested and absorbed, despite the different nutrients are absorbed at different speeds. In general, carbohydrates are digested quickly, followed by protein and finally fat. Micronutrients (vitamins and minerals) are composed of molecules small enough to be absorbed by the body without breaking them down first, but water soluble vitamins are absorbed faster than fat-soluble. The  duodenum  and jejunum is where the chyme is broken, while the ileum is responsible for the absorption of nutrients in the bloodstream. Absorbed nutrients pass through the bloodstream to the liver where it is processed and stored or distributed to other parts of the body. After every useful, digestible ingredients other than water has been removed from the chyme, the remaining “waste” is the large intestine. For more information, see Guide to digestion in the small intestine.

Converts energy from stored body fat to spare

Apart from the breakdown and absorption of nutrients, the digestive system also converts food into energy to power the muscles and fuel the millions of chemical reactions necessary for good health. After the immediate energy needs have been met, any excess is stored as glycogen (a small energy reserve liquid stored in the liver and muscles), or body fat. For more information, see Guide body fat and body fat / body fat – How fat gain.

The large intestine

Also known as the large intestine, large intestine – which consists of three sections, the cecum, colon and rectum is – about 5 feet long and has two main functions: to absorb the remaining water from food waste and to compress the remaining material in a compact package (feces or stool), so that the defecation (excretion of waste) is easy and convenient. The cecum is a pouch that contains a short valve that opens to receive the chyme in the ileum. The colon absorbs water and through bacterial action reduces the bulk of the fiber in the stool. The rectum is the terminal segment of the digestive tract, in which feces accumulate just prior to discharge. They are discharged through the anus, which contains two important muscles – the internal sphincter and external sphincter. The internal sphincter is always tight, except when stool enters the rectum, in order to keep the continent (for example) when we are asleep. When we get an urge to defecate, we depend on external sphincter to keep the stool until you go to the bathroom. In total, it takes about 36-48 hours or more for waste to pass through the large intestine. As in the esophagus and small intestine, large intestine contents are driven by a sequence of muscle contractions called peristalsis (a type of motility or muscle movement). Peristalsis is regulated by a large network of nerves, hormones and muscles. Malfunction of any of these components may lead to a series of intestinal problems, including indigestion and constipation. For more information, see Guide to digestion in the intestine.

Indigestion and other digestive disorders

Poor eating habits – such as excessive consumption of refined carbohydrates, or lack of dietary fiber – can cause constipation, indigestion, nonulcer dyspepsia, or may lead to certain digestion related to the specific conditions such as diverticulosis and syndrome Irritable Bowel (IBS), or nutritional deficiencies. Other digestive disorders include candida, celiac disease and lactose intolerance. Viral infections can lead to diarrhea and gastroenteritis that are specific to anti-diarrhea treatment diet may be urgent. Finally, the food ingested toxins can cause a number of unpleasant digestive problems or even food poisoning. For more information, see Diet Tips for digestion problems.