Where does the majority of digestion occur?


Food usually remains in the stomach for about two hours.The most important part of digestion takes place in the small intestine.

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Biology Digestion
Small intestine

The small intestine (or small bowel) is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. It receives bile juice and pancreatic juice through the hepatopancreatic duct, controlled by Sphincter of oddi. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to describe the entire intestine. This article is primarily about the human gut, though the information about its processes is directly applicable to most placental mammals. The primary function of the small intestine is the absorption of nutrients and minerals found in food. (A major exception to this is cows; for information about digestion in cows and other similar mammals, see ruminants.)


The stomach is a muscular, hollow, dilated part of the digestion system which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects (mid-gut), and molluscs. It is involved in the second phase of digestion, following mastication (chewing).

The stomach is located between the esophagus and the small intestine. It secretes protein-digesting enzymes called proteases and strong acids to aid in food digestion, (sent to it via esophageal peristalsis) through smooth muscular contortions (called segmentation) before sending partially digested food (chyme) to the small intestines.


In human anatomy, the intestine (or bowel, hose or gut) is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. In humans, the small intestine is further subdivided into the duodenum, jejunum and ileum while the large intestine is subdivided into the cecum and colon.


In botany, a stoma (plural stomata) (occasionally called a stomate, plural stomates) (from Greek στόμα, "mouth") is a pore, found in the epidermis of leaves, stems and other organs that is used to control gas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening. The term is also used collectively to refer to an entire stomatal complex, both the pore itself and its accompanying guard cells. Air containing carbon dioxide and oxygen enters the plant through these openings and is used in photosynthesis in the mesophyll cells (parenchyma cells with chloroplasts) and respiration, respectively. Oxygen produced as a by-product of photosynthesis diffuses out to the atmosphere through these same openings. Also, water vapor is released into the atmosphere through these pores in a process called transpiration.

Stomata are present in the sporophyte generation of all land plant groups except liverworts. Dicotyledons usually have more stomata on the lower epidermis than the upper epidermis. Monocotyledons, on the other hand, usually have the same number of stomata on the two epidermes. In plants with floating leaves, stomata may be found only on the upper epidermis; submerged leaves may lack stomata entirely.

Stomach disease

The stomach is an important organ in the body. It plays a vital role in digestion of foods, releases various enzymes and also protects the lower intestine from harmful organisms. The stomach connects to the esophagus above and to the small intestine below. It is intricately related to the pancreas, spleen and liver. The stomach does vary in size but its J shape is constant. The stomach lies in the upper part of the abdomen just below the left rib cage.

Gastropathy is a general term used for stomach disease. Examples including the name include portal hypertensive gastropathy and Ménétrier's disease, also known as "hyperplastic hypersecretory gastropathy". However, there are many other stomach diseases that don't include the word "gastropathy" such as gastric or peptic ulcer disease, gastroparesis, and dyspepsia.

Anaerobic digestion

Anaerobic digestion is a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to manage waste and/or to produce fuels. Much of the fermentation used industrially to produce food and drink products, as well as home fermentation, uses anaerobic digestion. Silage is produced by anaerobic digestion.

The digestion process begins with bacterial hydrolysis of the input materials. Insoluble organic polymers, such as carbohydrates, are broken down to soluble derivatives that become available for other bacteria. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. These bacteria convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Finally, methanogens convert these products to methane and carbon dioxide. The methanogenic archaea populations play an indispensable role in anaerobic wastewater treatments.

Digestive system

Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones.

In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication, a form of mechanical digestion, and the wetting contact of saliva. Saliva, a liquid secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food. After undergoing mastication and starch digestion, the food will be in the form of a small, round slurry mass called a bolus. It will then travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion. Gastric juice mainly contains hydrochloric acid and pepsin. As these two chemicals may damage the stomach wall, mucus is secreted by the stomach, providing a slimy layer that acts as a shield against the damaging effects of the chemicals. At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which is waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes.

Anatomy Medicine

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