For the industrial process see anaerobic digestion

Digestion is the process of metabolism whereby a biological entity processes a substance, in order to chemically and mechanically convert the substance into nutrients. Anaerobic digestion is the breakdown of organic matter by bacteria in the absence of oxygen. ... Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ... Chemistry (from Greek χημεία khemeia[1] meaning alchemy) is the science of matter at the atomic to molecular scale, dealing primarily with collections of atoms, such as gases, molecules, crystals, and metals. ... A nutrient is either element or compound necessary for or contributing to an organisms metabolism, growth, or other functioning. ...

Overview

Digestion occurs at the multicellular, cellular, and sub-cellular levels, usually in animals. This process takes place in the digestive system, gastrointestinal tract, or alimentary canal.

Digestion is usually divided into mechanical manipulation and chemical action. In most vertebrates, digestion is a multi-stage process in the digestive system, following ingestion of the raw materials, most often other organisms. The process of ingestion usually involves some type of mechanical manipulation. Digestion is separated into five separate processes: 1) Ingestion: Placing food into the mouth, 2) Mechanical digestion: Mastication, the use of teeth to tear and crush food, and churning of the stomach. 3) Chemical digestion: Addition of chemicals (acid, bile, enzymes, and water) to break down complex molecules into simple structures, 4) Absorption: Movement of nutrients from the digestive system to the circulatory and lymphatic capillaries through osmosis, active transport, and diffusion, 5) Elimination: Removal of undigested materials from the digestive tract through defecation. Underlying the process is muscle movement throughout the system, deglutition and peristalsis. Osmosis is the net movement of water through a selective permeable membrane from a region of low solute potential to a region of high solute potential (or equivalently, from a region of high solvent potential to a region of low solvent potential). ... Active transport is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. ... This article or section does not cite its references or sources. ... This article or section does not cite its references or sources. ... Swallowing, known scientifically as deglutition is the reflex in the human body that makes something pass from the mouth, through the esophagus. ... In much of the digestive tract, muscles contract in sequence to produce a peristaltic wave which forces food (called bolus while in the esophagus and chyme below the esophagus) along the alimentary canal. ...

Human digestion process

Human Gastrointestinal tract

In humans, digestion begins in the oral cavity where food is chewed (mastication) with the teeth. The process stimulates exocrine glands in the mouth to release digestive enzymes such as salivary amylase, which aid in the breakdown of starch. Chewing (mechanical catabolism) also causes the release of saliva, which helps condense food into a bolus that can be easily passed through the esophagus. The esophagus is about 20 centimeters long. Saliva also begins the process of chemical catabolism, hydrolysis. Once food is chewed properly, the food is swallowed. The bolus is pushed down by the movement called peristalsis, which is an involuntary wave-like contraction of smooth muscle tissue, characteristic of the digestive system. The mechanism for swallowing is co-ordinated by the swallowing centre in the medulla oblongata and pons. The reflex is initiated by touch receptors in the pharynx as a bolus of food is pushed to the back of the mouth by the tongue. The uvula is a small flap that hangs from the roof of the mouth. During swallowing it and the soft palate retract upward and to the rear to close the nasopharynx, which prevents the food from entering the nasal passages by triggering closure of the soft palate. When swallowed, the food enters the pharynx, which makes special adaptations to prevent choking or aspiration when food is swallowed. The epiglottis is a cartilage structure that closes temporarily during swallowing, preventing food and liquids from entering the trachea. Image File history File links Stomach_colon_rectum_diagram. ... Image File history File links Stomach_colon_rectum_diagram. ... This article is about modern humans. ... The gastrointestinal tract (GI tract), also called the digestive tract, alimentary canal, or gut, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. ... The mouth, also known as the buccal cavity or the oral cavity, is the opening through which an animal or human takes in food. ... Chewing is the process by which food is torn and/or crushed by teeth. ... Mastication or chewing is the process by which food is torn and/or crushed by teeth. ... Types of teeth Molars are used for grinding up foods Carnassials are used for slicing food. ... Exocrine gland refers to glands that secrete their products and temporarily store their secretions in a duct. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Salivary amylase is an enzyme produced by the salivary glands that begins carbohydrate digestion in the mouth and continues in the body of the stomach after the food and saliva have been swallowed. ... Starch (CAS# 9005-25-8) is a complex carbohydrate which is insoluble in water; it is used by plants as a way to store excess glucose. ... Anabolism is the aspect of metabolism that contributes to growth. ... Saliva is the watery and usually somewhat frothy substance produced in the mouths of some animals, including humans. ... Look up bolus in Wiktionary, the free dictionary. ... The esophagus (also spelled oesophagus/Å“sophagus), or gullet is an organ in vertebrates which consists of a muscular tube through which food passes from the mouth area to the stomach. ... The esophagus (also spelled oesophagus/Å“sophagus), or gullet is an organ in vertebrates which consists of a muscular tube through which food passes from the mouth area to the stomach. ... Hydrolysis is a chemical reaction or process in which a molecule is split into two parts by reacting with a molecule of water, which has the chemical formula H2O. One of the parts gets an OH- from the water molecule and the other part gets an H+ from the water. ... In much of the digestive tract, muscles contract in sequence to produce a peristaltic wave which forces food (called bolus while in the esophagus and chyme below the esophagus) along the alimentary canal. ... For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... The medulla oblongata is the lower portion of the brainstem. ... Diagram showing the uvula, tonsils, soft palate, and tongue Uvula without tonsils (after tonsillectomy) The uvula (IPA: ) is a small, mucosa-covered set of muscles, musculus uvulae, hanging down from the soft palate, near the back of the throat. ... Swallowing, known scientifically as deglutition, is the reflex in the human body that makes something pass from the mouth, to the pharynx, into the esophagus, with the shutting of the epiglottis. ... The soft palate, or velum, is the soft tissue comprising the back of the roof of the mouth. ... The pharynx is the part of the digestive system of many animals immediately behind the mouth and in front of the esophagus. ... The pharynx (plural: pharynges) is the part of the neck and throat situated immediately posterior to the mouth and nasal cavity, and cranial to the esophagus, larynx, and trachea. ... Choking is the obstruction of the flow of air into a persons lungs by a foreign object, commonly food. ... In medicine, aspiration is the entry of secretions or foreign material into the trachea and lungs. ... Haha u cant see this b/c wiess The epiglottis is a thin, lid-like flap of cartilage tissue covered with a mucous membrane, attached to the root of the tongue, that guards the entrance of the glottis, the opening between the vocal cords. ... Windpipe redirects here. ...

The food enters the stomach upon passage through the cardiac sphincter, also known as the esophageal sphincter. In the stomach, food is further broken apart through a process of heuristic churning and is thoroughly mixed with a digestive fluid, composed chiefly of hydrochloric acid, and other digestive enzymes to further denature proteins. The parietal cells of the stomach also secrete a compound, intrinsic factor which is essential in the absorption of vitamin B-12. As the acidic level changes in the small intestines, more enzymes are activated to split apart the molecular structure of the various nutrients so they may be absorbed into the circulatory or lymphatic systems. Absorption is when smaller molecules, such as glucose or alcohol, pass through the membrane of the stomach directly into the blood stream. In anatomy, the stomach (in ancient Greek στόμαχος) is an organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. ... The cardia is the anatomical term for the junction orifice of the stomach and the esophagus. ... Gastric acid is, together with several enzymes and the intrinsic factor, one of the main secretions of the stomach. ... The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl). ... Denaturation is a structural change in biomolecules such as nucleic acids and proteins, usually caused by heat, acids, bases, detergents, or certain chemicals such as urea. ... Parietal cells (also called oxyntic cells) are cells located in the stomach epithelium. ... Intrinsic factor is a glycoprotein produced by the parietal cells of the stomach. ... Cobalamin or vitamin B12 is a chemical compound that is also known as cyanocobalamine. ... The correct title of this article is . ... Look up absorption in Wiktionary, the free dictionary. ...

After being processed in the stomach, food is passed to the small intestine via the pyloric sphincter. This is where most of the digestive process occurs as chyme enters the first 10 inches (25 cm) of the small intestine, the duodenum. Here it is further mixed with 3 different liquids: (1) bile (which helps aid in fat digestion, otherwise known as emulsification), (2) pancreatic juice and enzymes, (made by the pancreas), and (3) intestinal enzymes of the alkaline mucosal membranes. The enzymes include: maltase, lactase and sucrase, to process sugars. Trypsin and chymotrypsin are other enzymes added in the small intestine. (Bile also contains pigments that are by-products of red blood cell destruction in the liver; these bile pigments are eliminated from the body with the feces.) Most nutrient absorption takes place in the small intestine. The nutrients pass through the small intestine's wall, which contains small, finger-like structures called villi. The blood, which has absorbed nutrients, is carried away from the small intestine via the hepatic portal vein and goes to the liver for filtering, removal of toxins, and nutrient processing. The primary activity here is regulation of blood glucose levels through a process of temporary storage of excess glucose that is converted in the liver to glycogen in direct response to the hormone insulin. Between meals, when blood glucose levels begin to drop, the glycogen is converted back to glucose in response to the hormone glucagon. In biology the small intestine is the part of the gastrointestinal tract (gut) between the stomach and the large intestine. ... From Greek pylorus; pyl- = gate, -orus = guard. ... Chyme is the liquid substance found in the stomach before passing the Pyloric valve and entering the duodenum. ... In anatomy of the digestive system, the duodenum is a hollow jointed tube connecting the stomach to the jejunum. ... Bile (or gall) is a bitter, greenish-yellow alkaline fluid secreted by hepatocytes from the liver of most vertebrates. ... Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... An emulsion is a mixture of two immiscible substances. ... Pancreatic juice is a juice produced by the pancreas. ... The pancreas is an organ in the digestive and endocrine system that serves two major functions: exocrine (producing pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including insulin). ... Maltase, drawn from PDB 1OBB. Maltase (EC 3. ... Lactase is a member of the β-galactosidase family of enzyme: enzymes that hydrolysis β 1,4 bonded attachments off of galactose. ... Headline text Sucrase (EC 3. ... Magnification of typical sugar showing monoclinic hemihedral crystalline structure. ... Trypsin (EC 3. ... Chymotrypsin (bovine γ chymotrypsin: PDB 1AB9, EC 3. ... Human red blood cells Red blood cells are the most common type of blood cell and the vertebrate bodys principal means of delivering oxygen from the lungs or gills to body tissues via the blood. ... The liver is an organ in some animals, including mammals (and therefore humans), birds, and reptiles. ... Villi (singular: villus) are tiny, finger-like structures that protrude from the wall of the intestine to help absorb nutrients in the lumen. ... The portal vein is a major vein in the human body draining blood from the digestive system and its associated glands. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Electron micrograph of a section of a liver cell showing glycogen deposits as accumulations of electron dense particles (arrows). ... Insulin (from Latin insula, island, as it is produced in the Islets of Langerhans in the pancreas) is a polypeptide hormone that regulates carbohydrate metabolism. ... Glucagon ball and stick model A microscopic image stained for glucagon. ...

After going through the small intestine, the food then goes to the large intestine. The large intestine has 3 parts: the cecum (or pouch that forms the T-junction with the small intestine), the colon, and the rectum. In the large intestine, water is reabsorbed, and the foods that cannot go through the villi, such as dietary fibre, can be stored in large intestine. Fibre helps to keep the food moving through the G.I. tract. The food that cannot be broken down is called feces. Feces are stored in the rectum until they are expelled through the anus. The large intestine is the last part of digestive system: the final stage of the alimentary canal in vertebrate animals. ... In anatomy of the digestive system, the cecum or caecum is a pouch connected to the large intestine between the ileum. ... Colon has several meanings: colon (anatomy) colon (punctuation) colon (rhetoric) See also Colón This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. ... Villi (singular: villus) are tiny, finger-like structures that protrude from the wall of the intestine to help absorb nutrients in the lumen. ... Dietary fibers are long-chain carbohydrates (polysaccharides) that are indigestible by the human digestive tract. ... Feces, faeces, or fæces (see spelling differences) is waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ... Female Human Anatomy Male Human Anatomy This article is about the bodily orifice. ...

Significance of pH in digestion

Digestion is a complex process which is controlled by several factors. pH plays a crucial role in a normally functioning digestive tract. In the mouth, pharynx, and esophagus, pH is typically about 6.8, a very weak acid. Saliva controls pH in this region of the digestive tract. Salivary amylase is contained in saliva and starts the breakdown of carbohydrates into monosaccharides. Most digestive enzymes are sensitive to pH and will not function in a low-pH environment like the stomach. Low pH (below 5) indicates a strong acid, while a high pH (above 8) indicates a strong base. The correct title of this article is . ... Saliva is the watery and usually somewhat frothy substance produced in the mouths of some animals, including humans. ... Salivary amylase is an enzyme produced by the salivary glands that begins carbohydrate digestion in the mouth and continues in the body of the stomach after the food and saliva have been swallowed. ... Monosaccharides are carbohydrates in the form of simple sugars. ... A base in chemistry is a chemical substance which has a free pair of electrons to bind a hydrogen ion commonly referred to as a proton (IUPAC definition). ...

pH in the stomach is very acidic and inhibits the breakdown of carbohydrates while there. The strong acid content of the stomach provides two benefits, both serving to denature proteins for further digestion in the small intestines, as well as providing non-specific immunity, retarding or eliminating various pathogens. Carbohydrates (literally hydrates of carbon) are chemical compounds that act as the primary biological means of storing or consuming energy, other forms being fat and protein. ... Denaturation is a structural change in biomolecules such as nucleic acids and proteins, usually caused by heat, acids, bases, detergents, or certain chemicals such as urea. ... A pathogen (literally birth of pain from the Greek παθογένεια) is a biological agent that can cause disease to its host. ...

In the small intestines, the duodenum provides critical pH balancing to activate digestive enzymes. The Liver secretes bile into the duodenum to neutralise the acidic conditions from the stomach. Also the pancreatic duct empties into the stomach, adding bicarbonate to neutralize the acidic chyme, thus creating a neutral environment. The mucosal tissue of the small intestines is alkaline, creating a pH of about 8.5, thus enabling absorption in a mild alkaline environment. A duct joining the pancreas to the bile duct to supply pancreatic juice which aid in digestion provided by the exocrine pancreas. ... In inorganic chemistry, a bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. ... Chyme is the liquid substance found in the stomach before passing the Pyloric valve and entering the duodenum. ...

References:

• Kimball's Biology Pages, Digestion
• Chemistry lecture
• American Journal of Physiology, article
• Journal article on pH in digestion

Specialized organs

Organisms develop specialized organs to aid in the digestion of their food, for example different types of tongues or teeth. Insects may have a crop (or the enlargement of oesophagus) while birds and cockroaches may develop a gizzard (or a stomach that acts as teeth and mechanically digests food). A herbivore may have a cecum that breaks down the cellulose in plants. Ruminants, for example, bovines and sheep, have a fourth and final stomach or abomasum. For other uses, see Tongue (disambiguation). ... The crop is a thin-walled expanded portion of the alimentary tract used for the storage of food prior to digestion that is found in many animals, including earthworms, leeches, insects, and birds. ... The esophagus, oe/œsophagus*, or gullet is the muscular tube in vertebrates through which ingested food passes from the mouth area to the stomach. ... The gizzard is an adapted stomach that is found in birds, earthworms, and other animals. ... A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... In anatomy of the digestive system, the cecum or caecum is a pouch connected to the large intestine between the ileum. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a long-chain polymeric polysaccharide carbohydrate, of beta-glucose [1][2]. It forms the primary structural component of green plants. ... Families Antilocapridae Bovidae Cervidae Giraffidae Moschidae Tragulidae A ruminant is any hooved animal that digests its food in two steps, first by eating the raw material and regurgitating a semi-digested form known as cud, then eating the cud, a process called ruminating. ... Tribes Bovini Boselaphini Strepsicerotini The biological subfamily Bovinae includes a diverse group of about 24 medium-sized to large ungulates, including domestic cattle, bison, the Water Buffalo, the Yak, and the four-horned and spiral-horned antelopes. ... Species See text. ... The abomasum is the fourth and final stomach compartment of the stomach in ruminants. ...

Digestive hormones

There are at least four hormones that aid and regulate the digestive system:

• Gastrin - is in the stomach and stimulates the gastric glands to secrete pepsinogen and hydrochloric acid. Secretion of gastrin is stimulated by food arriving in stomach. The secretion is inhibited by low pH .
• Secretin - is in the duodenum and signals the secretion of sodium bicarbonate in the pancreas and it stimulates the bile secretion in the liver. This hormone responds to the acidity of the chyme.
• Cholecystokinin (CCK) - is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gall bladder. This hormone is secreted in response to fat in chyme.
• Gastric inhibitory peptide (GIP) - is in the duodenum and decreases the stomach churning in turn slowing the emptying in the stomach.

In humans, gastrin is a hormone that stimulates secretion of gastric acid by the stomach. ... In anatomy, the stomach (in ancient Greek στόμαχος) is an organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. ... The fundus glands (or fundic glands, or gastric glands) are found in the body and fundus of the stomach. ... Pepsin is a protease, a digestive enzyme that degrades food proteins in the stomach; the other important digestive enzymes are trypsin and chymotrypsin. ... The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl). ... The correct title of this article is . ... Secretin is a peptide hormone produced in the S cells of the duodenum. ... In anatomy of the digestive system, the duodenum is a hollow jointed tube connecting the stomach to the jejunum. ... The pancreas is an organ in the digestive and endocrine system that serves two major functions: exocrine (producing pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including insulin). ... Bile (or gall) is a bitter, greenish-yellow alkaline fluid secreted by hepatocytes from the liver of most vertebrates. ... The liver is an organ in some animals, including mammals (and therefore humans), birds, and reptiles. ... Cholecystokinin (from Greek chole, bile; cysto, sac; kinin, move; hence, move the bile-sac (gall bladder)) is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. ... The gallbladder (or cholecyst) is a pear-shaped organ that stores bile (or gall) until the body needs it for digestion. ... Gastric inhibitory peptide (GIP) is a gastrointestinal hormone secreted by the duodenum. ...

Digestion chemistry

Carbohydrate digestion

Overview

Carbohydrates are formed in growing plants and are found in grains, leafy vegetables, and other edible plant foods. The molecular structure of these plants is complex, or a polysaccharide; poly is a prefix meaning many. Plants form carbohydrate chains during growth by trapping carbon from the atmosphere, initially carbon dioxide (CO₂). Carbohydrates (literally hydrates of carbon) are chemical compounds that act as the primary biological means of storing or consuming energy, other forms being fat and protein. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ...

Carbon is stored within the plant along with water (H₂O) to form a complex starch containing a combination of carbon-hydrogen-oxygen in a fixed ratio of 1:2:1 respectively.

Plants with a high sugar content and table sugar represent a less complex structure and are called disaccharides, or two sugar molecules bonded. Once digestion of either of these forms of carbohydrates are complete, the result is a single sugar structure, a monosaccharide. These monosaccharides can be absorbed into the blood and used by individual cells to produce the energy compound adenosine triphosphate(ATP). Sucrose, a common disaccharide A disaccharide is a sugar (a carbohydrate) composed of two monosaccharides. ... Monosaccharides are the simplest form of carbohydrates. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ...

The digestive system starts the process of breaking down polysaccharides in the mouth through the introduction of amylase, a digestive enzyme in saliva. The high acid content of the stomach inhibits the enzyme activity, so carbohydrate digestion is suspended in the stomach. Upon emptying into the small intestines, potential hydrogen (pH) changes dramatically from a strong acid to an alkaline content. The pancreas secretes bicarbonate to neutralize the acid from the stomach, and the mucus secreted in the tissue lining the intestines is alkaline which promotes digestive enzyme activity. Amalayse is present in the small intestines and works with other enzymes to complete the breakdown of carbohydrate into a monosaccharide which is absorbed into the surrounding capillaries of the villi. α-Amylase Amylase (EC 3. ... Saliva is the watery and usually somewhat frothy substance produced in the mouths of some animals, including humans. ... The common (Arrhenius) definition of a base is a chemical compound that either donates hydroxide ions or absorbs hydrogen ions when dissolved in water. ... In inorganic chemistry, a bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. ... Villi (singular: villus) are tiny, finger-like structures that protrude from the wall of the intestine to help absorb nutrients in the lumen. ...

Nutrients in the blood are transported to the liver via the hepatic portal circuit, or loop, where final carbohydrate digestion is accomplished in the liver. The liver accomplishes carbohydrate digestion in response to the hormones insulin and glucagon. As blood glucose levels increase following digestion of a meal, the pancreas secretes insulin causing the liver to transform glucose to glycogen, which is stored in the liver, adipose tissue, and in muscle cells, preventing hyperglycemia. A few hours following a meal, blood glucose will drop due to muscle activity, and the pancreas will now secrete glucagon which causes glycogen to be converted into glucose to prevent hypoglycemia . The liver is an organ in some animals, including mammals (and therefore humans), birds, and reptiles. ... Insulin (from Latin insula, island, as it is produced in the Islets of Langerhans in the pancreas) is a polypeptide hormone that regulates carbohydrate metabolism. ... Glucagon ball and stick model A microscopic image stained for glucagon. ... Electron micrograph of a section of a liver cell showing glycogen deposits as accumulations of electron dense particles (arrows). ... Hyperglycemia or High Blood Sugar is a condition in which an excessive amount of glucose circulates in the blood plasma. ... Hypoglycemia (hypoglycæmia in the UK) is a medical term referring to a pathologic state produced by a lower than normal amount of sugar (glucose) in the blood. ...

Note: In the discussion of digestion of carbohydrates; nouns ending in the suffix -ose usually indicate a sugar, lactose. Nouns ending in the suffix -ase indicates the enzyme that will break down the sugar, lactase. For example: lactose, sugar found naturally in milk, is digested by lactase resulting on a less complex molecule, a monosaccharide. Lactose is a disaccharide that consists of β-D-galactose and β-D-glucose molecules bonded through a β1-4 glycosidic linkage. ... Lactase is a member of the β-galactosidase family of enzyme: enzymes that hydrolysis β 1,4 bonded attachments off of galactose. ...

See also

• Anaerobic digestion
• Gastrointestinal tract

Anaerobic digestion is the breakdown of organic matter by bacteria in the absence of oxygen. ... The gastrointestinal tract (GI tract), also called the digestive tract, alimentary canal, or gut, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. ...

External links

• Gastric Digestion (Animation)
• Human Physiology - Digestion
• NIH guide to digestive system