Meat, even free-range or grain fed (organic), once out of the stomach, sits in our intestines for 24-72 hours depending on the type (chicken, beef pork), producing very toxic acids that many cancers feed off of.
Beef is the culinary name for meat from bovines, especially cattle. Beef can be harvested from cows, bulls, heifers or steers.
Beef muscle meat can be cut into steak, roasts or short ribs. Some cuts are processed (corned beef or beef jerky), and trimmings, usually mixed with meat from older, leaner cattle, are ground, minced or used in sausages. The blood is used in some varieties of blood sausage. Other parts that are eaten include the oxtail, liver, tongue, tripe from the reticulum or rumen, glands (particularly the pancreas and thymus, referred to as sweetbread), the heart, the brain (although forbidden where there is a danger of bovine spongiform encephalopathy, BSE), the liver, the kidneys, and the tender testicles of the bull (known in the US as calf fries, prairie oysters, or Rocky Mountain oysters). Some intestines are cooked and eaten as-is, but are more often cleaned and used as natural sausage casings. The bones are used for making beef stock.
Beef from steers and heifers is very similar, (all treatments being equal), except steers have slightly less fat and more muscle. Depending on economics, the number of heifers kept for breeding varies. Older animals are used for beef when they are past their reproductive prime. The meat from older cows and bulls is usually tougher, so it is frequently used for mince (UK)/ground beef (US). Cattle raised for beef may be allowed to roam free on grasslands, or may be confined at some stage in pens as part of a large feeding operation called a feedlot (or concentrated animal feeding operation), where they are usually fed a ration of grain, protein, roughage and a vitamin/mineral preblend.
Beef is the third most widely consumed meat in the world, accounting for about 25% of meat production worldwide, after pork and poultry at 38% and 30% respectively. In absolute numbers, the United States, Brazil, and the People's Republic of China are the world's three largest consumers of beef. On a per capita basis in 2009, Argentines ate the most beef at 64.6 kg per person; people in the US ate 40.2 kg, while those in the EU ate 16.9 kg.
The world's largest exporters of beef are India, Brazil, Australia and the United States. Beef production is also important to the economies of Paraguay, Argentina, Ireland, Mexico, New Zealand, Nicaragua, Russia, and Uruguay.
The word beef is from the Latin bōs, in contrast to cow, which is from Middle English "cou" (both words have the same Indo-European root ). After the Norman Conquest, the French-speaking nobles who ruled England naturally used French words to refer to the meats they were served. Thus various Anglo-Saxon words were used for the animal (such as nēat, or cu for adult females) by the peasants, but the meat was called boef (ox) (Modern French bœuf) by the French nobles —who did not often deal with the live animal— when it was served to them.
This is one example of the common English dichotomy between the words for animals (with largely Germanic origins) and their meat (with Romanic origins) that is also found in such English word-pairs as pig/pork, sheep/mutton and chicken/poultry.
Beef is cognate with bovine through the Late Latin bovīnus.
People have eaten the flesh of bovines from prehistoric times; some of the earliest known cave paintings, such as those of Lascaux show aurochs in hunting scenes. People domesticated cattle around 8000 BC to provide ready access to beef, milk, and leather. Most cattle originated in the Old World, with the exception of bison hybrids. Examples include the Wagyū from Japan, Ankole-Watusi from Egypt, and longhorn Zebu from the Indian subcontinent.
It is unknown exactly when people started cooking beef. Cattle were widely used across the Old World as draft animals (oxen), for milk, or specifically for meat. With mechanization of farming, some breeds were specifically bred to increase meat yield, resulting in Chianina and Charolais, or to improve texture, as the Murray Grey, Angus or Wagyū. Some breeds have been selected for both meat and milk production, e.g. Brown Swiss (Braunvieh).
Beef is first divided into primal cuts, pieces of meat initially separated from the carcass during butchering. These are basic sections from which steaks and other subdivisions are cut. The term "primal cut" is quite different from "prime cut", used to characterise cuts considered to be of higher quality. Since the animal's legs and neck muscles do the most work, they are the toughest; the meat becomes more tender as distance from hoof and horn increases. Different countries and cuisines have different cuts and names, and sometimes use the same name for a different cut; e.g., the cut described as "brisket" in the US is from a significantly different part of the carcass than British brisket.
In the United States, the USDA Agricultural Marketing Service (AMS) operates a voluntary beef grading program. The meat processor pays for a trained AMS meat grader to grade whole carcasses at the abattoir. Users are required to comply with Food Safety and Inspection Service (FSIS) grade labeling procedures. The official USDA grade designation can appear in one or any combination of the following ways: container markings, individual bags, legible roller brand appearing on the meat itself, or by a USDA shield stamp that incorporates the quality and/or yield grade.
There are eight beef quality grades. The grades are based on two main criteria: the degree of marbling (intramuscular fat) in the beef, and the maturity (estimated age of the animal at slaughter). Some meat scientists][ object to the current scheme of USDA grading since it is not based on direct measurement of tenderness, although marbling and maturity are indicators of tenderness. Most other countries' beef grading systems mirror the US model. Most beef offered for sale in supermarkets is graded US Choice or Select. US Prime beef is sold to hotels and upscale restaurants, and usually marketed as such. Beef that would rate as US Standard or less is almost never offered for grading.
Utility, Cutter, and Canner grade are rarely used in foodservice operations and primarily used by processors and canners.
Beef grading service began in 1917 as a way to determine both the quality and the quantity of beef that would come from each carcass. Stamping the grades began in May 1927. Each carcass can be stamped with a yield or quality stamp, or a combination of both. The standards have been revised many times since the original standards were formulated. A few notable changes include combining Prime and choice grades into Prime, and changing the Good grade to choice, this change occurred in 1950. In 1980 conditions were set forth to establish guidance on grading protocol. This included a 10 minute bloom time before the grader evaluates the carcass. Most beef plants will allow a longer time for bloom depending on the speed of the grading chain. In 1997, the official standards were revised to restrict the Select grade to A maturity carcasses, and to raise the minimum marbling score to qualify for Choice to modest for B maturity cattle. These changes were implemented to improve the uniformity and consistency of the grading system. Yield grades are intended to estimate the pounds of boneless closely trimmed retail cuts from the carcass. Closely trimmed refers to approximately ¼ inch of external fat. The yield grade is determined by considering 4 carcass characteristics: external fat, Kidney Pelvic and heart fat, Ribeye area, and Hot carcass weight. The amount of external fat is measured at the ribbed surface between the 12th-13th ribs. The ribbing of carcasses is described in the US standards for beef grading. External fat is measured at a distance of ¾ the length of the ribeye from the chine bone end. This initial number can be adjusted up or down depending on any abnormal fat deposits. As the amount of external fat increases, the percent of retail cuts decreases. Kidney fat is measured subjectively and is expressed as a percentage of the carcass weight. As the percentage of KPH increases, the percent of retail cuts decreases. The ribeye area is measured at the ribbed surface, it can be estimated subjectively or measured with a device approved by the AMS. As ribeye area increase, percent retail cuts increases. Hot carcass weight is used to determine yield grade. As carcass weight increases, percent retail cuts decrease. The following equation is used to determine yield grade:
There are five grades, 1-5. Yield grade one carcasses are of the highest cutability, while yield grade 5 yields the lowest cutability.
Beef sold in US restaurants and supermarkets is usually described by its USDA grade; however, in the early twentyfirst century many restaurants and retailers began selling beef on the strength of brand names and the reputation of a specific breed of cattle, such as black Angus.
To improve tenderness of beef, it often is aged (i.e., stored refrigerated) to allow endogenous proteolytic enzymes to weaken structural and myofibrillar proteins. Wet aging is accomplished using vacuum packaging to reduce spoilage and yield loss. Dry aging involves hanging primals (usually ribs or loins) in humidity-controlled coolers. Outer surfaces dry out and can support growth of molds (and spoilage bacteria, if too humid), resulting in trim and evaporative losses.
Evaporation concentrates the remaining proteins and increases flavor intensity; the molds can contribute a nut-like flavor. After two to three days there are significant effects. The majority of the tenderizing effect occurs in the first 10 days. Boxed beef, stored and distributed in vacuum packaging, is, in effect, wet aged during distribution. Premium steakhouses dry age for 21 to 28 days or wet age up to 45 days for maximum effect on flavor and tenderness.
Meat from less tender cuts or older cattle can be mechanically tenderized by forcing small, sharp blades through the cuts to disrupt the proteins. Also, solutions of exogenous proteolytic enzymes (papain, bromelin or ficin) can be injected to augment the endogenous enzymes. Similarly, solutions of salt and sodium phosphates can be injected to soften and swell the myofibrillar proteins. This improves juiciness and tenderness. Salt can improve the flavor, but phosphate can contribute a soapy flavor.
These methods are applicable to all types of meat and some other foodstuffs.
Beef can be cooked to various degrees, from very rare to well done. The degree of cooking corresponds to the temperature in the approximate center of the meat, which can be measured with a meat thermometer. Beef can be cooked using the sous vide method, which cooks the entire steak to the same temperature, but when cooked using a method such as broiling or roasting it is typically cooked such that it has a "bulls eye" of doneness, with the least done (coolest) at the center and the most done (warmest) at the outside.
While searing and the Maillard Reaction are important to the final flavor of a piece of beef, the degree of doneness is also important. A chef can judge the degree of doneness of steak using the finger touch test, without a meat thermometer. Temperature ranges can be found at Temperature (meat).
Meat can be cooked in boiling oil, typically by shallow frying, although deep frying may be used, often for meat enrobed with breadcrumbs as in milanesas. Larger pieces such as steaks may be cooked this way, or meat may be cut smaller as in stir frying, typically an Asian way of cooking: cooking oil with flavourings such as garlic, ginger and onions is put in a very hot wok. Then small pieces of meat are added, followed by ingredients which cook more quickly, such as mixed vegetables. The dish is ready when the ingredients are 'just cooked'.
Moist heat cooking methods include braising, pot roasting, stewing and sous vide. These techniques are often used for cuts of beef that are tougher, as these longer, lower-temperature cooking methods have time to dissolve connecting tissue which otherwise makes meat remain tough after cooking.
Meat has usually been cooked in water which is just simmering, such as in stewing; higher temperatures make meat tougher by causing the proteins to contract. Since thermostatic temperature control became available, cooking at temperatures well below boiling, (sous-vide) to (slow cooking), for prolonged periods has become possible; this is just hot enough to convert the tough collagen in connective tissue into gelatin through hydrolysis, with minimal toughening.
With the adequate combination of temperature and cooking time, pathogens, such as bacteria will be killed, and Pasteurization can be achieved. Because browning (Maillard reactions) can only occur at higher temperatures (above the boiling point of water), these moist techniques do not develop the flavors associated with browning. Meat will often undergo searing in a very hot pan, grilling or browning with a torch before moist cooking (though sometimes after).
Thermostatically controlled methods, such as sous-vide, can also prevent overcooking by bringing the meat to the exact degree of doneness desired, and holding it at that temperature indefinitely. The combination of precise temperature control and long cooking duration makes it possible to be assured that Pasteurization has been achieved, both on the surface and the interior of even very thick cuts of meat, which can not be assured with most other cooking techniques. (Although extremely long-duration cooking can break down the texture of the meat to an undesirable degree.)
Beef can be cooked quickly at the table through several techniques. In hot pot cooking, such as shabu-shabu, very thinly sliced meat is cooked by the diners at the table by immersing it in a heated pot of water or stock with vegetables. In fondue bourguignonne, diners dip small pieces of beef into a pot of hot oil at the table. Both techniques typically feature accompanying flavorful sauces to complement the meat.
Steak tartare is a French dish made from finely chopped or ground (minced) raw meat (often beef). More accurately, it is scraped so as not to let even the slightest of the sinew fat get into the scraped meat. It is often served with onions, capers, seasonings such as fresh ground pepper and Worcestershire sauce, and sometimes raw egg yolk.
The Belgian dish filet américain is also made of finely chopped ground beef, though it is seasoned differently, and either eaten as a main dish or can be used as a dressing for a sandwich. Kibbeh nayyeh is a similar Lebanese dish. And in Ethiopia, a ground raw meat dish called tire siga or kitfo is eaten (upon availability).
Carpaccio of beef is a thin slice of raw beef dressed with olive oil, lemon juice and seasoning. Often, the beef is partially frozen before slicing to allow very thin slices to be cut.
Yukhoe is a variety of hoe, raw dishes in Korean cuisine which is usually made from raw ground beef seasoned with various spices or sauces. The beef part used for yukhoe is tender rump steak. For the seasoning, soy sauce, sugar, salt, sesame oil, green onion, and ground garlic, sesame seed, black pepper and juice of bae (Korean pear) are used. The beef is mostly topped with the yolk of a raw egg.
Bresaola is an air-dried, salted beef that has been aged about two to three months until it becomes hard and a dark red, almost purple, colour. It is lean, has a sweet, musty smell and is tender. It originated in Valtellina, a valley in the Alps of northern Italy's Lombardy region. Bündnerfleisch is a similar product from neighbouring Switzerland.
Beef jerky is dried, salted, smoked beef popular in the United States.
Biltong is a cured, salted, air dried beef popular in South Africa.
Pastrami is often made from beef; raw beef is salted, then partly dried and seasoned with various herbs and spices, and smoked.
Corned beef is a cut of beef cured or pickled in a seasoned brine. The corn in corned beef refers to the grains of coarse salts (known as corns) used to cure it. The term corned beef can denote different styles of brine-cured beef, depending on the region. Some, like American-style corned beef, are highly seasoned and often considered delicatessen fare.
Spiced beef is a cured and salted joint of round, topside, or silverside, traditionally served at Christmas in Ireland. It is a form of salt beef, cured with spices and saltpetre, intended to be boiled or broiled in Guinness or a similar stout, and then optionally roasted for a period after. There are various other recipes for pickled beef. Sauerbraten is a German variant.
Hindus consider killing cattle and eating beef a sin, and Jains are forbidden to eat any kind of meat. Similarly, Vaishnavism considers eating meat to be an act against the virtue of mercy and compassion towards animals, and hence strictly prohibits eating meat of any kind. Killing of cows and bulls (including calves) is considered to be an extremely great sin by Vaishnavism. Bovines have been highly revered as sacred to mankind in Indian culture][ due to the critical role of cattle, especially cows, as a source of milk, and dairy products, and their relative importance to the pastoral Vedic people allowed this special status; and this rose to prominence with the advent of the Jain tradition and Hindu Golden-age during the Gupta period. The slaughter of cattle has been likened to the matricide in these cultures, due to the idealisation of the cow providing milk and sustenance for society.
Cow slaughter is currently banned in many states - Gujarat passed the Animal Preservation Act in October 2011 that prohibits killing of cows along with buying, selling and transport of beef. Orissa and Andhra Pradesh states allow butchering of cattle other than cows if the animal carries a "fit-for-slaughter" certificate. But in West Bengal, Kerala, Goa etc. consumption of beef is not deemed an offence. Kerala and Goa have a considerable number of Christians who consume beef. In Kerala, beef is either curried or made as a stir fry called beef fry.
During the season of Lent, Catholics traditionally give up all meat and poultry as a religious act. Observant Jews and Muslims may not eat any meat or poultry which has not been slaughtered and treated in conformance with religious laws.
Beef is an excellent source of complete protein and minerals such as zinc, selenium, phosphorus and iron, and B vitamins. Red meat is the most significant dietary source of carnitine and, like any other meat (pork, fish, veal, lamb etc.), is a source of creatine.
A study released in 2007 by the World Cancer Research Fund reported "strong evidence that red meat [defined as 'beef, pork, lamb, and goat from domesticated animals'] and processed meats are causes of bowel cancer" and recommended that people eat less than 500 grams (18 oz) of cooked red meat weekly, and as little processed meat as possible. The report also recommended that average consumption in populations should not exceed 300 grams (11 oz) per week, stating this goal "corresponds to the level of consumption of red meat at which the risk of colorectal cancer can clearly be seen to rise."
Cardiovascular disease and coronary heart disease
The Harvard School of Public Health also recommends consumers eat red meat sparingly as it has high levels of undesirable saturated fat. This recommendation is not without controversy, though. Another study from The Harvard School of Public Health appearing in Circulation (journal) found "Consumption of processed meats, but not red meats, is associated with higher incidence of coronary heart disease and diabetes mellitus."
This finding tended to confirm an earlier meta-analysis of the nutritional effects of saturated fat in The American Journal of Clinical Nutrition which found "[P]rospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of coronary heart disease or cardiovascular disease. More data are needed to elucidate whether cardiovascular disease risks are likely to be influenced by the specific nutrients used to replace saturated fat."
Some cattle raised in the United States feed on pastures fertilized with sewage sludge. Elevated dioxins may be present in meat from these cattle.
Ground beef has been subject to recalls in the United States, due to E. coli contamination:
In 1984, the use of meat and bone meal in cattle feed resulted in the world's first outbreak of bovine spongiform encephalopathy (BSE or, colloquially, mad cow disease) in the United Kingdom.
Since then, other countries have had outbreaks of BSE:
In 2010, more than 20 years after the disease emerged, the EU tentatively decided to relax a ban on feeding meat to animals, introduced to prevent the transmission of BSE by that route.
Top 10 cattle and beef producing countries
Beef production (1000 MT CWE)
National cattle herds (1000 Head)
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 protease 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.
The word stomach is derived from the Latin stomachus which is derived from the Greek word stomachos (στόμαχος), ultimately from stoma (), "mouth". The words gastro- and gastric (meaning related to the stomach) are both derived from the Greek word gaster ().
Bolus (masticated food) enters the stomach through the esophagus via the esophageal sphincter. The stomach releases proteases (protein-digesting enzymes such as pepsin) and hydrochloric acid, which kills or inhibits bacteria and provides the acidic pH of two for the proteases to work. Food is churned by the stomach through muscular contractions of the wall called peristalsis – reducing the volume of the fundus, before looping around the fundus and the body of stomach as the boluses are converted into chyme (partially digested food). Chyme slowly passes through the pyloric sphincter and into the duodenum of the small intestine, where the extraction of nutrients begins. Depending on the quantity and contents of the meal, the stomach will digest the food into chyme anywhere between forty minutes and a few hours. The average human stomach can comfortably hold about a liter of food.
Gastric juice in the stomach also contains pepsinogen and prorennin. Hydrochloric acid activates these inactive forms of enzymes into active forms which are pepsin and rennin (proteases). Rennin digests the milk protein caesinogen (soluble) into caesin (insoluble) thus curdling the milk. Pepsin breaks down proteins into polypeptides.
The stomach lies between the esophagus and the duodenum (the first part of the small intestine). It is on the left upper part of the abdominal cavity. The top of the stomach lies against the diaphragm. Lying behind the stomach is the pancreas. The greater omentum hangs down from the greater curvature.
Two sphincters keep the contents of the stomach contained. They are the esophageal sphincter (found in the cardiac region, not an anatomical sphincter) dividing the tract above, and the pyloric sphincter dividing the stomach from the small intestine.
The stomach is surrounded by parasympathetic (stimulant) and orthosympathetic (inhibitor) plexuses (networks of blood vessels and nerves in the anterior gastric, posterior, superior and inferior, celiac and myenteric), which regulate both the secretions activity and the motor (motion) activity of its muscles.
In adult humans, the stomach has a relaxed, near empty volume of about 45 to 75 ml. Because it is a distensible organ, it normally expands to hold about one litre of food, but can hold as much as two to three litres. The stomach of a newborn human baby will only be able to retain about 30 ml.
The stomach is divided into four sections, each of which has different cells and functions. The sections are:
The lesser curvature of the stomach is supplied by the right gastric artery inferiorly, and the left gastric artery superiorly, which also supplies the cardiac region. The greater curvature is supplied by the right gastroepiploic artery inferiorly and the left gastroepiploic artery superiorly. The fundus of the stomach, and also the upper portion of the greater curvature, is supplied by the short gastric artery which arises from splenic artery.
Like the other parts of the gastrointestinal tract, the stomach walls are made of the following layers, from inside to outside:
Over the submucosa, the muscularis externa in the stomach differs from that of other GI organs in that it has three layers of smooth muscle instead of two.
Different types of cells are found at the different layers of these glands:
The movement and the flow of chemicals into the stomach are controlled by both the autonomic nervous system and by the various digestive system hormones:
Other than gastrin, these hormones all act to turn off the stomach action. This is in response to food products in the liver and gall bladder, which have not yet been absorbed. The stomach needs to push food into the small intestine only when the intestine is not busy. While the intestine is full and still digesting food, the stomach acts as storage for food.
Epidermal growth factor (EGF) results in cellular proliferation, differentiation, and survival. EGF is a low-molecular-weight polypeptide first purified from the mouse submandibular gland, but since then found in many human tissues including submandibular gland, parotid gland. Salivary EGF, which seems also regulated by dietary inorganic iodine, plays also an important physiological role in the maintenance of oro-oesophageal and gastric tissue integrity. The biological effects of salivary EGF include healing of oral and gastroesophageal ulcers, inhibition of gastric acid secretion, stimulation of DNA synthesis as well as mucosal protection from intraluminal injurious factors such as gastric acid, bile acids, pepsin, and trypsin and to physical, chemical and bacterial agents.
The stomach can "taste" sodium glutamate using glutamate receptors and this information is passed to the lateral hypothalamus and limbic system in the brain as a palatability signal through the vagus nerve. The stomach can also sense independently to tongue and oral taste receptors glucose, carbohydrates proteins, and fats. This allows the brain to link nutritional value of foods to their tastes.
Although the absorption is mainly a function of the small intestine, some absorption of certain small molecules nevertheless does occur in the stomach through its lining. This includes:
A large number of studies have indicated that most cases of peptic ulcers, gastritis, and stomach cancer are caused by Helicobacter pylori infection. The stomach has to regenerate a new layer of mucus every two weeks, or else damage to the epithelium may result.
Although the precise shape and size of the stomach varies widely among different vertebrates, the relative positions of the esophageal and duodenal openings remain relatively constant. As a result, the organ always curves somewhat to the left before curving back to meet the pyloric sphincter. However, lampreys, hagfishes, chimaeras, lungfishes, and some teleost fish have no stomach at all, with the esophagus opening directly into the intestine. These animals all consume diets that either require little storage of food, or no pre-digestion with gastric juices, or both.
The gastric lining is usually divided into two regions, an anterior portion lined by fundic glands, and a posterior with pyloric glands. Cardiac glands are unique to mammals, and even then are absent in a number of species. The distributions of these glands vary between species, and do not always correspond with the same regions as in man. Furthermore, in many non-human mammals, a portion of the stomach anterior to the cardiac glands is lined with epithelium essentially identical to that of the esophagus. Ruminants, in particular, have a complex stomach, the first three chambers of which are all lined with esophageal mucosa.
In birds and crocodilians, the stomach is divided into two regions. Anteriorly is a narrow tubular region, the proventriculus, lined by fundic glands, and connecting the true stomach to the crop. Beyond lies the powerful muscular gizzard, lined by pyloric glands, and, in some species, containing stones that the animal swallows to help grind up food.
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Gastric acid is a digestive fluid, formed in the stomach. It has a pH of 1.5 to 3.5 and is composed of hydrochloric acid (HCl) (around 0.5%, or 5000 parts per million) as high as 0.1 M, and large quantities of potassium chloride (KCl) and sodium chloride (NaCl). The acid plays a key role in digestion of proteins, by activating digestive enzymes, and making ingested proteins unravel so that digestive enzymes break down the long chains of amino acids.
Gastric acid is produced by cells lining the stomach, which are coupled to systems to increase acid production when needed. Other cells in the stomach produce bicarbonate, a base, to buffer the fluid, ensuring that it does not become too acidic. These cells also produce mucus, which forms a viscous physical barrier to prevent gastric acid from damaging the stomach. Cells in the beginning of the small intestine, or duodenum, further produce large amounts of bicarbonate to completely neutralize any gastric acid that passes further down into the digestive tract.
The presence of gastric acid in the stomach and its function in digestion was first characterized by United States Army surgeon William Beaumont around 1830. Beaumont was able to study the stomach action of fur trapper Alexis St. Martin due to the latter's gastric fistula.
Gastric acid is produced by parietal cells (also called oxyntic cells) in the stomach. Its secretion is a complex and relatively energetically expensive process. Parietal cells contain an extensive secretory network (called canaliculi) from which the gastric acid is secreted into the lumen of the stomach. These cells are part of epithelial fundic glands in the gastric mucosa. The pH of gastric acid is 1.35 to 3.5 in the human stomach lumen, the acidity being maintained by the proton pump ATPase+/K+H. The parietal cell releases bicarbonate into the blood stream in the process, which causes a temporary rise of pH in the blood, known as alkaline tide.
The resulting highly acidic environment in the stomach lumen causes proteins from food to lose their characteristic folded structure (or denature). This exposes the protein's peptide bonds. The chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen and rennin). Hydrochloric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis. In addition, many microorganisms have their growth inhibited by such an acidic environment, which is helpful to prevent infection.
Gastric acid secretion happens in several steps. Chloride and hydrogen ions are secreted separately from the cytoplasm of parietal cells and mixed in the canaliculi. Gastric acid is then secreted into the lumen of the oxyntic gland and gradually reaches the main stomach lumen. The exact manner in which the secreted acid reaches the stomach lumen is controversial, as acid must first cross the relatively pH neutral gastric mucus layer.
Chloride and sodium ions are secreted actively from the cytoplasm of the parietal cell into the lumen of the canaliculus. This creates a negative potential of -40 mV to -70 mV across the parietal cell membrane that causes potassium ions and a small number of sodium ions to diffuse from the cytoplasm into the parietal cell canaliculi.
The enzyme carbonic anhydrase catalyses the reaction between carbon dioxide and water to form carbonic acid. This acid immediately dissociates into hydrogen and bicarbonate ions. The hydrogen ions leave the cell through ATPase+/K+H antiporter pumps.
At the same time sodium ions are actively reabsorbed. This means that the majority of secreted K+ and Na+ ions return to the cytoplasm. In the canaliculus, secreted hydrogen and chloride ions mix and are secreted into the lumen of the oxyntic gland.
The highest concentration that gastric acid reaches in the stomach is 160 mM in the canaliculi. This is about 3 million times that of arterial blood, but almost exactly isotonic with other bodily fluids. The lowest pH of the secreted acid is 0.8, but the acid is diluted in the stomach lumen to a pH between 1 and 3.
There are three phases in the secretion of gastric acid:
There is also a small continuous basal secretion of gastric acid between meals of usually less than 10 mEq/hour.
Gastric acid production is regulated by both the autonomic nervous system and several hormones. The parasympathetic nervous system, via the vagus nerve, and the hormone gastrin stimulate the parietal cell to produce gastric acid, both directly acting on parietal cells and indirectly, through the stimulation of the secretion of the hormone histamine from enterochromaffine-like cells (ECL). Vasoactive intestinal peptide, cholecystokinin, and secretin all inhibit production.
The production of gastric acid in the stomach is tightly regulated by positive regulators and negative feedback mechanisms. Four types of cells are involved in this process: parietal cells, G cells, D cells and enterochromaffine-like cells. Besides this, the endings of the vagus nerve (CN X) and the intramural nervous plexus in the digestive tract influence the secretion significantly.
Nerve endings in the stomach secrete two stimulatory neurotransmitters: acetylcholine and gastrin-releasing peptide. Their action is both direct on parietal cells and mediated through the secretion of gastrin from G cells and histamine from enterochromaffine-like cells. Gastrin acts on parietal cells directly and indirectly too, by stimulating the release of histamine.
The release of histamine is the most important positive regulation mechanism of the secretion of gastric acid in the stomach. Its release is stimulated by gastrin and acetylcholine and inhibited by somatostatin.
In the duodenum, gastric acid is neutralized by sodium bicarbonate. This also blocks gastric enzymes that have their optima in the acid range of pH. The secretion of sodium bicarbonate from the pancreas is stimulated by secretin. This polypeptide hormone gets activated and secreted from so-called S cells in the mucosa of the duodenum and jejunum when the pH in duodenum falls below 4.5 to 5.0. The neutralization is described by the equation:
The carbonic acid rapidly equilibrates with carbon dioxide and water through catalysis by carbonic anhydrase enzymes bound to the gut epithelial lining, leading to a net release of carbon dioxide gas within the lumen associated with neutralisation. In the absorptive upper intestine, such as the duodenum, both the dissolved carbon dioxide and carbonic acid will tend to equilibrate with the blood, leading to most of the gas produced on neutralisation being exhaled through the lungs.
In hypochlorhydria and achlorhydria, there is low or no gastric acid in the stomach, potentially leading to problems as the disinfectant properties of the gastric lumen are decreased. In such conditions, there is greater risk of infections of the digestive tract (such as infection with Vibrio or Helicobacter bacteria).
In Zollinger–Ellison syndrome and hypercalcemia, there are increased gastrin levels, leading to excess gastric acid production, which can cause gastric ulcers.
In diseases featuring excess vomiting, patients develop hypochloremic metabolic alkalosis (decreased blood acidity by H+ and chlorine depletion).
The proton pump enzyme is the target of proton pump inhibitors, used to increase gastric pH (and hence decrease stomach acidity) in diseases that feature excess acid. antagonists2H indirectly decrease gastric acid production. Antacids neutralize existing acid.
The role of gastric acid in digestion was established in the 1820s and 1830s by William Beaumont on Alexis St. Martin, who, as a result of an accident, had a fistula (hole) in his stomach, which allowed Beaumont to observe the process of digestion and to extract gastric acid, verifying that acid played a crucial role in digestion.
G cells (gastrin) D cells (somatostatin) ECL cells (Histamine)
enterogastrone: I cells (CCK) K cells (GIP) S cells (secretin)
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Pork is the culinary name for meat from the domestic pig (Sus domesticus). It is one of the most commonly consumed meats worldwide, with evidence of pig husbandry dating back to 5000 BC.
Pork is eaten both freshly cooked and preserved. Curing extends the shelf life of the pork products. Hams, smoked pork, gammon, bacon and sausage are examples of preserved pork. Charcuterie is the branch of cooking devoted to prepared meat products, many from pork.
Fresh pork may contain Trichinosis. USDA recommends cooking ground pork to an internal temperature of 160°F, followed by a 3 minute rest, and cooking whole cuts to a minimum internal temperature of 145°F, also followed by a 3 minute rest.
The pig is one of the oldest forms of livestock, having been domesticated as early as 5000 BC. It is believed to have been domesticated either in the Near East or in China from the wild boar][. The adaptable nature and omnivorous diet of this creature allowed early humans to domesticate it much earlier than many other forms of livestock, such as cattle. Pigs were mostly used for food, but people also used their hides for shields and shoes, their bones for tools and weapons, and their bristles for brushes. Pigs have other roles within the human economy: their feeding behaviour in searching for roots churns up the ground and makes it easier to plough; their sensitive noses lead them to truffles, an underground fungus highly valued by humans; and their omnivorous nature enables them to eat human rubbish, keeping settlements cleaner.
Charcuterie is the branch of cooking devoted to prepared meat products such as bacon, ham, sausage, terrines, galantines, pâtés, and confit, primarily from pork. Originally intended as a way to preserve meats before the advent of refrigeration, these preparations are prepared today for the flavours that are derived from the preservation processes. In 15th century France, local guilds regulated tradesmen in the food production industry in each city. The guilds that produced charcuterie were those of the charcutiers. The members of this guild produced a traditional range of cooked or salted and dried meats, which varied, sometimes distinctively, from region to region. The only "raw" meat the charcutiers were allowed to sell was unrendered lard. The charcutier prepared numerous items, including pâtés, rillettes, sausages, bacon, trotters, and head cheese.
Before the mass production and re-engineering of pork in the 20th century, pork in Europe and North America was traditionally an autumn dish — pigs and other livestock coming to the slaughter in the autumn after growing in the spring and fattening during the summer. Due to the seasonal nature of the meat in Western culinary history, apples (harvested in late summer and autumn) have been a staple pairing to fresh pork. The year-round availability of meat and fruits has not diminished the popularity of this combination on Western plates.
Pork is one of the most widely eaten meats in the world, accounting for about 38% of meat production worldwide, although consumption varies widely from place to place.
According to the USDA's Foreign Agricultural Service, nearly 100 million metric tons of pork were consumed worldwide in 2006 (preliminary data). Increasing urbanization and disposable income has led to a rapid rise in pork consumption in China, where 2006 consumption was 20% higher than in 2002, and a further 5% increase projected in 2007.
Pork is popular throughout eastern Asia and the Pacific, where whole roast pig is a popular item in Pacific Island cuisine. It is consumed in a great many ways and highly esteemed in Chinese cuisine. There, pork is preferred over beef for economic and aesthetic reasons; the pig is easy to feed and is not used for labour. The colours of the meat and the fat of pork are regarded as more appetizing, while the taste and smell are described as sweeter and cleaner. It is also considered easier to digest. In rural tradition, pork is shared to celebrate important occasion and to form bonding.
Pork may be cooked from fresh meat or cured over time. Cured meat products include ham and bacon. The carcass may be used in many different ways for fresh meat cuts, with the popularity of certain cuts and certain carcass proportions varying worldwide.
Most of the carcass can be used to produce fresh meat and in the case of a suckling pig, the whole body of a young pig ranging in age from two to six weeks is roasted. Danish roast pork or flæskesteg, prepared with crispy crackling is a national favourite as the traditional Christmas dinner.
Pork is particularly common as an ingredient in sausages. Many traditional European sausages are made with pork, including chorizo, fuet, Cumberland sausage and salami. Many brands of American hot dogs and most breakfast sausages are made from pork. Processing of pork into sausages and other products in France is described as charcuterie.
Ham and bacon are made from fresh pork by curing with salt (pickling) and/or smoking. Shoulders and legs are most commonly cured in this manner for Picnic shoulder and ham, whereas streaky and round bacon come from the side (round from the loin and streaky from the belly).
Ham and bacon are popular foods in the west, and their consumption has increased with industrialisation. Non-western cuisines also use preserved meat products. For example, salted preserved pork or red roasted pork is used in Chinese and Asian cuisine.
Bacon is defined as any of certain cuts of meat taken from the sides, belly or back that have been cured and/or smoked. In continental Europe, it is used primarily in cubes (lardons) as a cooking ingredient valued both as a source of fat and for its flavour. In Italy, besides being used in cooking, bacon (pancetta) is also served uncooked and thinly sliced as part of an antipasto. Bacon is also used for barding roasts, especially game birds. Bacon is often smoked, using various types of wood, a process which can take up to ten hours. Bacon may be eaten fried, baked, or grilled.
A side of unsliced bacon is a "flitch" or "slab bacon", while an individual slice of bacon is a "rasher" (Australia, Ireland, New Zealand and the United Kingdom) or simply a "slice" or "strip" (North America). Slices of bacon are also known as "collops". Traditionally, the skin is left on the cut and is known as "bacon rind". Rindless bacon, however, is quite common. In both Ireland and the United Kingdom, bacon comes in a wide variety of cuts and flavours, and is predominantly known as "streaky bacon", or "streaky rashers". Bacon made from the meat on the back of the pig is referred to as "back bacon" and is part of traditional full breakfast commonly eaten in Britain and Ireland. In the United States, back bacon may also be referred to as "Canadian-style Bacon" or "Canadian Bacon".
The USDA defines bacon as "the cured belly of a swine carcass", while other cuts and characteristics must be separately qualified (e.g. "smoked pork loin bacon"). "USDA Certified" bacon means that it has been treated for Trichinella.
The canned meat Spam is made of chopped pork shoulder meat and ham.
The pig is well known for being able to be used from nose-to-tail. There are different systems of naming for cuts in America, Britain and France.
Feijoada, the national dish of Brazil (also served in Portugal), is prepared with pork trimmings: ears, tail and feet.
Its myoglobin content is lower than that of beef, but much higher than that of chicken. The USDA treats pork as a red meat. Pork is very high in thiamin (vitamin B1). Pork with its fat trimmed is leaner than the meat of most domesticated animals, but is high in cholesterol and saturated fat.
In 1987 the U.S. National Pork Board began an advertising campaign to position pork as "the other white meat" — due to a public perception of chicken and turkey (white meat) as healthier than red meat. The campaign was highly successful and resulted in 87% of consumers identifying pork with the slogan. The board retired the slogan on March 4, 2011.
Eating of pork is prohibited by orthodox Jewish dietary laws and Islamic dietary laws, and is also avoided by mainstream Seventh-day Adventists, Rastafarians, and members of the Ethiopian Orthodox Church. It is considered unclean by some adherents of Hinduism, but the (disputed) Scottish pork taboo disappeared by 1800.
Pork is a well-known example of a non-kosher food. This prohibition is based on Leviticus chapter 11 and Deuteronomy chapter 14:
As indicated by the Torah verses, pork is non-kosher because Jews may not consume an animal that possesses one trait but not the other of cloven hooves and regurgitating cud. Hogs, which are not ruminants, do not chew cud as cattle and sheep do.
In Israel pig-raising has been limited by law to certain areas and institutions. Some pig-related laws are openly circumvented. Swine production has increased from an estimated annual slaughter of 50,000 swine in 1960 to 180,000 in 2010. Pigmeat consumption per capita was 2.7 kg in 2009. Although pork marketing is prohibited in some religious localities, pork products are available elsewhere at non-kosher butchers and by the Mizra and Tiv Ta'am non-kosher supermarket chain which caters to Russian immigrants. A modern Hebrew euphemism for pork is "white meat".
Pork is prohibited by the Islamic dietary laws. Throughout the Islamic world many countries severely restrict the importation or consumption of pork products. Examples are Iran, Mauritania, Oman, Qatar, Saudi Arabia, Kuwait, Pakistan and Maldives. However, in other Muslim countries such as Egypt, Turkey, Malaysia and parts of the UAE such as Dubai, pork is available in international hotels and some supermarkets that cater for expatriates and non-Muslims.
The Qur'anic basis for the Islamic prohibition of pork can be found in suras 2:173, 5:3, 5:60, 6:145 and 16:115.
Chapter (Sura) 2 - Verse (Ayat) 173 Al-Baqara (The Cow)
"He has forbidden you only the Maitah (dead animals), and blood, and the flesh of swine, and that which is slaughtered as a sacrifice for others than Allah. But if one is forced by necessity, without wilful disobedience, nor transgressing due limits, then there is no sin on him. Truly, Allah is Oft-forgiving Most Merciful."
Pork is known to carry some diseases such as pork tapeworm and trichinosis, thus uncooked or undercooked pork can be dangerous to consume.
Undercooked or untreated pork may harbour pathogens, or can be recontaminated after cooking if left exposed for a long period of time. In one instance, the Food Safety and Inspection Service (FSIS) detected Listeria monocytogenes in 460 lbs of Polidori brand fully cooked pork sausage crumbles, although no one was made ill from consumption of the product. The FSIS has previously stated Listeria and other microorganisms will be "destroyed by proper handling and thorough cooking to an internal temperature of " and that other microorganisms, such as E. coli, Salmonella, and Staphylococcus aureus can be found in inadequately cooked pork, poultry, and other meats. The FSIS, a part of the USDA, currently recommends cooking ground pork to and whole cuts to followed by a 3-minute rest.
The pig is the carrier of various helminths, such as roundworms, pinworms, hookworms, etc. One of the most common is Taenia solium, a type of tapeworm. Tapeworms may transplant to the intestines of humans when they consume undercooked meat from pigs or other animals.
Although not a common cause of illness, Yersinia enterocolitica – which causes gastroenteritis – is present in various foods, but is most frequently caused by eating uncooked or undercooked pork and can grow in refrigerated conditions. The bacteria can be killed by heat. Nearly all outbreaks in the US have been traced to pork.
Pork may be the reservoir responsible for sporadic, locally acquired cases of acute hepatitis E (HEV) reported in regions with relatively mild climates. It has been found to transmit between swine and humans.
Trichinosis, also called trichinellosis, or trichiniasis, is a parasitic disease caused by eating raw or undercooked pork infected with the larvae of a species of roundworm Trichinella spiralis, commonly called the trichina worm. Infection was once very common, but is now rare in the developed world. From 2002 to 2007, an annual average of 11 cases per year were reported in the United States; the majority were from consuming wild game or the source was unknown. The number of cases has decreased because of legislation prohibiting the feeding of raw meat garbage to hogs, increased commercial and home freezing of pork, and the public awareness of the danger of eating raw or undercooked pork or wild game products.
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.
The structure and function can be described both as gross anatomy and at a microscopic level. The intestine is divided into two parts: The small intestine and the large intestine. People will have different sized intestines according to their size and age. The lumen is the cavity where digested food passes through and from where nutrients are absorbed. Both intestines share a general structure with the whole gut, and are composed of several layers. Going from inside the lumen radially outwards, one passes the mucosa (glandular epithelium and muscularis mucosa), sub mucosa, muscularis externa (made up of inner circular and outer longitudinal), and lastly serosa.
The large intestine hosts several kinds of bacteria that deal with molecules the human body is not able to break down itself.][ This is an example of symbiosis. These bacteria also account for the production of gases inside our intestine (this gas is released as flatulence when eliminated through the anus). However the large intestine is mainly concerned with the absorption of water from digested material (which is regulated by the hypothalamus) and the re absorption of sodium, as well as any nutrients that may have escaped primary digestion in the ileum.
Animal intestines have multiple uses. From each species of livestock that is a source of milk, a corresponding rennet is obtained from the intestines of milk-fed calves. Pig and calf intestines are eaten, and pig intestines are used as sausage casings. Calf intestines supply Calf Intestinal Alkaline Phosphatase (CIP), and are used to make Goldbeater's skin.
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The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (dinosaurs, birds, crocodiles and alligators), earthworms, some gastropods and some fish. This specialized stomach constructed of thick, muscular walls is used for grinding up food; often rocks are instrumental in this process. In certain insects and mollusks, the gizzard features chitinous plates or teeth.
The word "gizzard" comes from the Middle English giser, which derives from a similar word in Old French, which itself evolved from the Latin gigeria, meaning giblets.
Birds swallow food and store it in their crop if necessary. Then the food passes into their glandular stomach, also called the proventriculus, which is also sometimes referred to as the true stomach. This is the secretory part of the stomach. Then the food passes into the ventriculus (also known as the muscular stomach or gizzard). The gizzard can grind the food with previously-swallowed stones and pass it back to the true stomach, and vice versa. Bird gizzards are lined with a tough layer made of the carbohydrate-protein complex koilin, to protect the muscles in the gizzard and to aid in digestion.][
Some animals that lack teeth will swallow stones or grit to aid in digestion. All birds have gizzards, but not all will swallow stones or grit. The birds that do, employ the following method of mastication:
These stones are called gizzard stones or gastroliths and are usually round and smooth from the polishing action in the animal's stomach. When too smooth to do their required work, they may be passed or regurgitated.
The mullet (Mugilidae) found in estuarine waters worldwide, and the gizzard or mud shad, found in freshwater lakes and streams from New York to Mexico, have gizzards. The gillaroo (Salmo stomachius), a richly colored species of trout found in the Irish lake, lough Melvin in County Fermanagh, has a gizzard which is used to aid the digestion of water snails, the main component of its diet.
Alligators and crocodiles also have gizzards.
Dinosaurs which are believed to have had gizzards based on the discovery of gizzard stones recovered near fossils include:
Claosaurus had been believed to have a gizzard, but this was A) Edmontosaurus annectens and B) probably based on stream-washed gravel; see Creisler, Benjamin S. 2007. Deciphering duckbills. Page 199 in Carpenter, Kenneth (ed.). Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Indiana University Press: Bloomington and Indianapolis.
All birds have gizzards. The gizzards of emus, turkeys, chickens and ducks are most notable in cuisine (see below).
Poultry gizzards are a popular food throughout the world. Grilled chicken gizzards are sold as street food in Haiti and throughout Southeast Asia. In Indonesia, gizzard and liver are considered as part of a complete fried poultry dish. Stewed gizzards are eaten as a snack in Portugal, while pickled turkey gizzards are a traditional food in some parts of the Midwestern United States. In Hungary it is made with paprika. In Nigeria gizzard is either grilled or fried and served with stew and fried plantain. In the Southern United States, the gizzard is typically served fried, sometimes eaten with hot sauce or honey mustard, or added to crawfish boil along with crawfish sauce, and it is also used in traditional New Orleans gumbo. In Chicago, gizzard is battered, deep fried and served with fries and sauce. Gizzard and mashed potato is a popular food in many European countries. In France, especially the Dordogne region, duck gizzards are eaten in the traditional Perigordian Salad, along with walnuts, croutons and lettuce. The Chamber of Commerce in Potterville, Michigan has held a Gizzard Fest each June since 2000; a gizzard-eating contest is among the weekend's events. In Iran some kebab restaurants mix chicken gizzards in their koobideh kebabs to increase the meat content. In Italy gizzards are often used mixed with other offals.
In Japan, gizzard is called 'zuri' or 'sunagimo', usually it is cooked in yakitori (Japanese style skewered barbecue). In Kyushu (southern Japan), gizzard is fried into karaage.
The word "Sangdana" is commonly used to refer to chicken gizzards in Pakistan. The word is derived from Persian (Sang = stone and dana = grain). Another name for it is the "Pathri". It may be served cooked in a curry while barbecued skewered gizzards are also popular.
In Nepal, gizzard is called "jaatey" or "pangra". It is eaten most often with the drinks.
In Yiddish, gizzards are referred to as "pipik'lach", literally meaning navels. The gizzards of kosher species of birds have a green or yellowish membrane lining the inside, which must be peeled off before cooking, as it lends a very bitter taste to the food. In traditional Eastern European Jewish cuisine, the gizzards, necks, and feet of chickens were often cooked together, although not the liver, which per Kosher law must be broiled. Kosher butchers often sell roasting chickens with the gizzard, neck, and feet butchered and left in the cavity to be used for making chicken soup.
In Uganda, Cameroon and Nigeria, the gizzard of a cooked chicken is traditionally set aside for the oldest or most respected male at the table.
Giblets consist of the heart, liver and gizzard of a bird, and are often eaten themselves or used as the basis for a soup or stock.
In Taiwan, gizzards are often slow-cooked and served hot or cold in slices, with green onions and soy sauce.
In Trinidad and Tobago, gizzards are curried and served with rice, roti, etc.
In Mainland China, duck gizzard is a common snack, eaten alongside other duck parts such as feet, neck, heart, tongue, or head. Areas famous for their gizzard are Sichuan and Hubei provinces. Wuhan city in Hubei is famous for its brand of spicy gizzard, called Jiujiuya (Simplified Chinese:久久鸭). In Northern China, one can find barbecued duck gizzard.
The term "gizzard" can also, by extension, refer to the general guts, innards or entrails of animals.
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 heptopancreatic duct, controlled by Spincter 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 average length of the small intestine in an adult human male is 6.9 m (22 feet 6 inches), and in an adult female 7.1 m (23 feet 4 inches). It can vary greatly, from as short as 4.6 m (15 feet) to as long as 9.8 m (32 feet). It is approximately 2.5–3 cm in diameter.
The small intestine is divided into three structural parts:
The three sections of the small intestine look similar to each other at a microscopic level, but there are some important differences. The parts of the intestine are as follows:
Food from the stomach is allowed into the duodenum through the pylorus by a muscle called the pyloric sphincter.
The small intestine is where most chemical digestion takes place. Most of the digestive enzymes that act in the small intestine are secreted by the pancreas and enter the small intestine via the pancreatic duct. Enzymes enter the small intestine in response to the hormone cholecystokinin, which is produced in the small intestine in response to the presence of nutrients. The hormone secretin also causes bicarbonate to be released into the small intestine from the pancreas in order to neutralize the potentially harmful acid coming from the stomach.
The three major classes of nutrients that undergo digestion are proteins, lipids (fats) and carbohydrates:
Digested food is now able to pass into the blood vessels in the wall of the intestine through the process of diffusion. The small intestine is the site where most of the nutrients from ingested food are absorbed. The inner wall, or mucosa, of the small intestine is lined with simple columnar epithelial tissue. Structurally, the mucosa is covered in wrinkles or folds called plicae circulares, which are considered permanent features in the wall of the organ. They are distinct from rugae which are considered non-permanent or temporary allowing for distention and contraction. From the plicae circulares project microscopic finger-like pieces of tissue called villi (Latin for "shaggy hair"). The individual epithelial cells also have finger-like projections known as microvilli. The function of the plicae circulares, the villi and the microvilli is to increase the amount of surface area available for the absorption of nutrients.
Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries (amino acids and carbohydrates) and lacteals (lipids). The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by our body. The food that remains undigested and unabsorbed passes into the large intestine.
Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions:
The small intestine is a complex organ, and as such, there are a very large number of possible conditions that may affect the function of the small bowel. A few of them are listed below, some of which are common, with up to 10% of people being affected at some time in their lives, while others are vanishingly rare.
The small intestine is found in all tetrapods and also in teleosts, although its form and length vary enormously between species. In teleosts, it is relatively short, typically around one and a half times the length of the fish's body. It commonly has a number of pyloric caeca, small pouch-like structures along its length that help to increase the overall surface area of the organ for digesting food. There is no ileocaecal valve in teleosts, with the boundary between the small intestine and the rectum being marked only by the end of the digestive epithelium.
In tetrapods, the ileocaecal valve is always present, opening into the colon. The length of the small intestine is typically longer in tetrapods than in teleosts, but is especially so in herbivores, as well as in mammals and birds, which have a higher metabolic rate than amphibians or reptiles. The lining of the small intestine includes microscopic folds to increase its surface area in all vertebrates, but only in mammals do these develop into true villi.
The boundaries between the duodenum, jejunum, and ileum are somewhat vague even in humans, and such distinctions are either ignored when discussing the anatomy of other animals, or are essentially arbitrary.
There is no small intestine as such in non-teleost fish, such as sharks, sturgeons, and lungfish. Instead, the digestive part of the gut forms a spiral intestine, connecting the stomach to the rectum. In this type of gut, the intestine itself is relatively straight, but has a long fold running along the inner surface in a spiral fashion, sometimes for dozens of turns. This valve greatly increases both the surface area and the effective length of the intestine. The lining of the spiral intestine is similar to that of the small intestine in teleosts and non-mammalian tetrapods.
In lampreys, the spiral valve is extremely small, possibly because their diet requires little digestion. Hagfish have no spiral valve at all, with digestion occurring for almost the entire length of the intestine, which is not subdivided into different regions.
Lower half of right sympathetic cord.
Topography of thoracic and abdominal viscera.
Cross section of human abdomen.
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The Federal Reserve System (also known as the Federal Reserve, and informally as the Fed) is the central banking system of the United States. It was created on December 23, 1913, with the enactment of the Federal Reserve Act, largely in response to a series of financial panics, particularly a severe panic in 1907. Over time, the roles and responsibilities of the Federal Reserve System have expanded and its structure has evolved. Events such as the Great Depression were major factors leading to changes in the system.
The U.S. Congress established three key objectives for monetary policy in the Federal Reserve Act: Maximum employment, stable prices, and moderate long-term interest rates. The first two objectives are sometimes referred to as the Federal Reserve's dual mandate. Its duties have expanded over the years, and today, according to official Federal Reserve documentation, include conducting the nation's monetary policy, supervising and regulating banking institutions, maintaining the stability of the financial system and providing financial services to depository institutions, the U.S. government, and foreign official institutions. The Fed also conducts research into the economy and releases numerous publications, such as the Beige Book. Agriculture
Free range is a term which denotes a method of farming husbandry where the animals can roam freely for food, rather than being confined in an enclosure. On many farms, the outdoors ranging area is fenced, thereby technically making this an enclosure, however, free range systems usually offer the opportunity for extensive locomotion and sunlight prevented by indoor housing systems. Free range may apply to meat, eggs or dairy farming.
The term is used in two senses that do not overlap completely: as a farmer-centric description of husbandry methods, and as a consumer-centric description of them. There is a diet where the practitioner only eats meat from free-range sources called ethical omnivorism, which is a type of semivegetarian. Beef
Different cattle feeding production systems have separate advantages and disadvantages. Most cows have a diet that is composed of at least some forage (grass, legumes, or silage). In fact most beef cattle are raised on pasture from birth in the spring until autumn (7 to 9 months).]citation needed[Then for pasture-fed animals, grass is the forage that composes all or at least the great majority of their diet. Cattle fattened in feedlots are fed small amounts of hay or straw supplemented with grain, soy and other ingredients in order to increase the energy density of the diet. The debate is whether cattle should be raised on diets primarily composed of pasture (grass) or a concentrated diet of grain, soy, corn and other supplements. The issue is often complicated by the political interests and confusion between labels such as "free range", "organic", or "natural". Cattle raised on a primarily forage diet are termed grass-fed or pasture-raised; for example meat or milk may be called grass-fed beef or pasture-raised dairy. However, the term "pasture-raised" can lead to confusion with the term "free range", which does not describe exactly what the animals eat.
Animals grazing in rangelands, pastures, and grasslands and with little or no integration of crops involved. About 60% of the world's pasture land is covered by grazing systems. Grazing systems supply approximately 9 percent of the world's production of beef, according to Food and Agriculture Organization FAO statistics. Offal
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells in an effort to produce energy, maintain life, or stimulate growth.
Historically, people secured food through two methods: hunting and gathering, and agriculture. Today, most of the food energy consumed by the world population is supplied by the food industry. Zoology