In a multicellular organism , an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life , an organ lies between tissue and an organ system . Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue . Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system.
85-446: The pancreas is an organ of the digestive system and endocrine system of vertebrates . In humans, it is located in the abdomen behind the stomach and functions as a gland . The pancreas is a mixed or heterocrine gland , i.e., it has both an endocrine and a digestive exocrine function. 99% of the pancreas is exocrine and 1% is endocrine. As an endocrine gland , it functions mostly to regulate blood sugar levels , secreting
170-410: A coil. These aneurysms represent around 2% of aneurysms in visceral arteries of the abdomen . Pseudoaneurysm may also occur. The inferior pancreaticoduodenal artery may be more simply known by the acronym IPDA. [REDACTED] This article incorporates text in the public domain from page 607 of the 20th edition of Gray's Anatomy (1918) This cardiovascular system article
255-441: A different hormone. These cells have characteristic positions, with alpha cells (secreting glucagon ) tending to be situated around the periphery of the islet, and beta cells (secreting insulin ) more numerous and found throughout the islet. Enterochromaffin cells are also scattered throughout the islets. Islets are composed of up to 3,000 secretory cells, and contain several small arterioles to receive blood, and venules that allow
340-452: A rich blood supply, with vessels originating as branches of both the coeliac artery and superior mesenteric artery . The splenic artery , the largest branch of the celiac trunk, runs along the top of the pancreas, and supplies the left part of the body and the tail of the pancreas through its pancreatic branches, the largest of which is called the greater pancreatic artery . The superior and inferior pancreaticoduodenal arteries run along
425-430: A rich lymphatic supply. The lymphatic vessels of the body and tail drain into splenic lymph nodes , and eventually into lymph nodes that lie in front of the aorta , between the coeliac and superior mesenteric arteries. The lymphatic vessels of the head and neck drain into intermediate lymphatic vessels around the pancreaticoduodenal, mesenteric and hepatic arteries, and from there into the lymph nodes that lie in front of
510-409: A role. Activation of Beta-2 receptors of the sympathetic nervous system by catecholamines secreted from sympathetic nerves stimulates secretion of insulin and glucagon, whereas activation of Alpha-1 receptors inhibits secretion. M3 receptors of the parasympathetic nervous system act when stimulated by the right vagus nerve to stimulate release of insulin from beta cells. The pancreas plays
595-411: A single layer of column-shaped cells . There is more than one layer of cells as the diameter of the ducts increases. The tissues with an endocrine role within the pancreas exist as clusters of cells called pancreatic islets (also called islets of Langerhans ) that are distributed throughout the pancreas. Pancreatic islets contain alpha cells , beta cells , and delta cells , each of which releases
680-412: A smaller accessory pancreatic duct run through the body of the pancreas. The main pancreatic duct joins with the common bile duct forming a small ballooning called the ampulla of Vater (hepatopancreatic ampulla). This ampulla is surrounded by a muscle, the sphincter of Oddi . This ampulla opens into the descending part of the duodenum . The opening of the common bile duct into main pancreatic duct
765-416: A variety of organ systems . These specific systems are widely studied in human anatomy . The functions of these organ systems often share significant overlap. For instance, the nervous and endocrine system both operate via a shared organ, the hypothalamus . For this reason, the two systems are combined and studied as the neuroendocrine system . The same is true for the musculoskeletal system because of
850-420: A vital role in the digestive system . It does this by secreting a fluid that contains digestive enzymes into the duodenum , the first part of the small intestine that receives food from the stomach . These enzymes help to break down carbohydrates, proteins and lipids (fats). This role is called the "exocrine" role of the pancreas. The cells that do this are arranged in clusters called acini . Secretions into
935-687: A whole, are referred to as the Organon because logic is a tool for philosophical thinking. Earlier thinkers, such as those who wrote texts in the Hippocratic corpus , generally did not believe that there were organs of the body but only different parts of the body. Some alchemists (e.g. Paracelsus ) adopted the Hermetic Qabalah assignment between the seven vital organs and the seven classical planets as follows: Chinese traditional medicine recognizes eleven organs, associated with
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#17327876403061020-402: Is 71. Risk factors include chronic pancreatitis, older age, smoking, obesity , diabetes , and certain rare genetic conditions including multiple endocrine neoplasia type 1 , hereditary nonpolyposis colon cancer and dysplastic nevus syndrome among others. About 25% of cases are attributable to tobacco smoking , while 5–10% of cases are linked to inherited genes . Pancreatic adenocarcinoma
1105-441: Is a branch of the superior mesenteric artery . It supplies the head of the pancreas , and the ascending and inferior parts of the duodenum . Rarely, it may have an aneurysm . The inferior pancreaticoduodenal artery is a branch of the superior mesenteric artery . This occurs opposite the upper border of the inferior part of the duodenum . As soon as it branches, it divides into anterior and posterior branches. These run between
1190-454: Is controlled by sphincter of Boyden . The accessory pancreatic duct opens into duodenum with separate openings located above the opening of the main pancreatic duct . The head of the pancreas sits within the curvature of the duodenum, and wraps around the superior mesenteric artery and vein. To the right sits the descending part of the duodenum, and between these travel the superior and inferior pancreaticoduodenal arteries . Behind rests
1275-436: Is found as a number of discrete nodules within the wall of the gut itself, with the exocrine portions being little different from other glandular structures of the intestine. The pancreas of calf ( ris de veau ) or lamb ( ris d'agneau ), and, less commonly, of beef or pork , are used as food under the culinary name of sweetbread . Organ (anatomy) An organ's tissues can be broadly categorized as parenchyma ,
1360-517: Is given the FOLFIRINOX regimen containing fluorouracil , irinotecan , oxaliplatin and leucovorin has been shown to extend survival beyond traditional gemcitabine regimens. For the most part, treatment is palliative , focus on the management of symptoms that develop. This may include management of itch , a choledochojejunostomy or the insertion of stents with ERCP to facilitate the drainage of bile, and medications to help control pain. In
1445-448: Is likely to cause intense pain in the central abdomen , that often radiates to the back, and may be associated with nausea or vomiting. Severe pancreatitis may lead to bleeding or perforation of the pancreas resulting in shock or a systemic inflammatory response syndrome , bruising of the flanks or the region around the belly button . These severe complications are often managed in an intensive care unit . In pancreatitis, enzymes of
1530-466: Is no discrete pancreas at all, with pancreatic tissue being distributed diffusely across the mesentery and even within other nearby organs, such as the liver or spleen . In a few teleost species, the endocrine tissue has fused to form a distinct gland within the abdominal cavity, but otherwise it is distributed among the exocrine components. The most primitive arrangement, however, appears to be that of lampreys and lungfish , in which pancreatic tissue
1615-452: Is often the first symptom that a person with type 1 diabetes may have, can result. Type 1 diabetes can develop at any age but is most often diagnosed before age 40. For people living with type 1 diabetes, insulin injections are critical for survival. An experimental procedure to treat type 1 diabetes is pancreas transplantation or isolated transplantation of islet cells to supply a person with functioning beta cells. Diabetes mellitus type 2
1700-415: Is possible for a person to live without a pancreas, provided that the person takes insulin for proper regulation of blood glucose concentration and pancreatic enzyme supplements to aid digestion. The pancreas was first identified by Herophilus (335–280 BC), a Greek anatomist and surgeon . A few hundred years later, Rufus of Ephesus , another Greek anatomist, gave the pancreas its name. Etymologically,
1785-438: Is secreted from centroacinar and ductal cells through a sodium and bicarbonate cotransporter that acts because of membrane depolarisation caused by the cystic fibrosis transmembrane conductance regulator . Secretin and VIP act to increase the opening of the cystic fibrosis transmembrane conductance regulator, which leads to more membrane depolarisation and more secretion of bicarbonate. A variety of mechanisms act to ensure that
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#17327876403061870-406: Is the placenta , which has evolved more than 100 times independently in vertebrates, has evolved relatively recently in some lineages, and exists in intermediate forms in extant taxa. Studies on the evolution of the placenta have identified a variety of genetic and physiological processes that contribute to the origin and evolution of organs, these include the re-purposing of existing animal tissues,
1955-496: Is the most common form of diabetes. The causes for high blood sugar in this form of diabetes usually are a combination of insulin resistance and impaired insulin secretion, with both genetic and environmental factors playing a role in the development of the disease. Over time, pancreatic beta cells may become "exhausted" and less functional. The management of type 2 diabetes involves a combination of lifestyle measures, medications if required and potentially insulin . With relevance to
2040-494: Is the most common form of pancreatic cancer, and is cancer arising from the exocrine digestive part of the pancreas. Most occur in the head of the pancreas. Symptoms tend to arise late in the course of the cancer, when it causes abdominal pain, weight loss, or yellowing of the skin ( jaundice ). Jaundice occurs when the outflow of bile is blocked by the cancer. Other less common symptoms include nausea, vomiting, pancreatitis, diabetes or recurrent venous thrombosis . Pancreatic cancer
2125-460: Is the most common symptom. When the digestive function of the pancreas is severely affected, this may lead to problems with fat digestion and the development of steatorrhoea ; when the endocrine function is affected, this may lead to diabetes. Chronic pancreatitis is investigated in a similar way to acute pancreatitis. In addition to management of pain and nausea, and management of any identified causes (which may include alcohol cessation ), because of
2210-479: Is usually diagnosed by medical imaging in the form of an ultrasound or CT scan with contrast enhancement. An endoscopic ultrasound may be used if a tumour is being considered for surgical removal, and biopsy guided by ERCP or ultrasound can be used to confirm an uncertain diagnosis. Because of the late development of symptoms, most cancer presents at an advanced stage . Only 10 to 15% of tumours are suitable for surgical resection. As of 2018, when chemotherapy
2295-478: The duodenal part of the foregut , an embryonic tube that is a precursor to the gastrointestinal tract . It is of endodermal origin. Pancreatic development begins with the formation of a dorsal and ventral pancreatic bud . Each joins with the foregut through a duct. The dorsal pancreatic bud forms the neck, body, and tail of the developed pancreas, and the ventral pancreatic bud forms the head and uncinate process. The definitive pancreas results from rotation of
2380-509: The five Chinese traditional elements and with yin and yang , as follows: The Chinese associated the five elements with the five planets (Jupiter, Mars, Venus, Saturn, and Mercury) similar to the way the classical planets were associated with different metals. The yin and yang distinction approximates the modern notion of solid and hollow organs. Inferior pancreaticoduodenal artery The inferior pancreaticoduodenal artery (the IPDA )
2465-418: The haruspices or the augurs in order to divine the future by their shape, dimensions or other factors. This practice remains an important ritual in some remote, tribal societies. The term "visceral" is contrasted with the term " parietal ", meaning "of or relating to the wall of a body part, organ or cavity " The two terms are often used in describing a membrane or piece of connective tissue, referring to
2550-431: The hormones insulin , glucagon , somatostatin and pancreatic polypeptide . As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct . This juice contains bicarbonate , which neutralizes acid entering the duodenum from the stomach; and digestive enzymes , which break down carbohydrates , proteins and fats in food entering
2635-444: The inferior vena cava , and the common bile duct . In front sits the peritoneal membrane and the transverse colon . A small uncinate process emerges from below the head, situated behind the superior mesenteric vein and sometimes artery . The neck of the pancreas separates the head of the pancreas, located in the curvature of the duodenum, from the body. The neck is about 2 cm (0.79 in) wide, and sits in front of where
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2720-434: The pancreatic bud , and the other dorsally . In most species (including humans), these "fuse" in the adult, but there are several exceptions. Even when a single pancreas is present, two or three pancreatic ducts may persist, each draining separately into the duodenum (or equivalent part of the foregut). Birds , for example, typically have three such ducts. In teleost fish, and a few other species (such as rabbits ), there
2805-420: The portal vein is formed. The neck lies mostly behind the pylorus of the stomach, and is covered with peritoneum. The anterior superior pancreaticoduodenal artery travels in front of the neck of the pancreas. The body is the largest part of the pancreas, and mostly lies behind the stomach, tapering along its length. The peritoneum sits on top of the body of the pancreas, and the transverse colon in front of
2890-417: The stomach , intestines , gallbladder , bladder , and rectum . In the thoracic cavity , the heart is a hollow, muscular organ. Splanchnology is the study of the viscera. The term "visceral" is contrasted with the term " parietal ", meaning "of or relating to the wall of a body part, organ or cavity ". The two terms are often used in describing a membrane or piece of connective tissue, referring to
2975-424: The vagus nerve . Secretin is released from the S cells which form part of the lining of the duodenum in response to stimulation by gastric acid. Along with VIP, it increases the secretion of enzymes and bicarbonate. Cholecystokinin is released from Ito cells of the lining of the duodenum and jejunum mostly in response to long chain fatty acids, and increases the effects of secretin. At a cellular level, bicarbonate
3060-461: The 20th century, organ transplants began to take place as scientists knew more about the anatomy of organs. These came later in time as procedures were often dangerous and difficult. Both the source and method of obtaining the organ to transplant are major ethical issues to consider, and because organs as resources for transplant are always more limited than demand for them, various notions of justice, including distributive justice , are developed in
3145-478: The United States pancreatic cancer is the fourth most common cause of deaths due to cancer. The disease occurs more often in the developed world, which had 68% of new cases in 2012. Pancreatic adenocarcinoma typically has poor outcomes with the average percentage alive for at least one and five years after diagnosis being 25% and 5% respectively. In localized disease where the cancer is small (< 2 cm)
3230-441: The acquisition of new functional properties by these tissues, and novel interactions of distinct tissue types. The study of plant organs is covered in plant morphology . Organs of plants can be divided into vegetative and reproductive. Vegetative plant organs include roots , stems , and leaves . The reproductive organs are variable. In flowering plants , they are represented by the flower , seed and fruit . In conifers ,
3315-445: The aorta. The pancreas contains tissue with an endocrine and exocrine role, and this division is also visible when the pancreas is viewed under a microscope. The majority of pancreatic tissue has a digestive role. The cells with this role form clusters ( Latin : acini ) around small ducts , and are arranged in lobes that have thin fibrous walls. The cells of each acinus secrete inactive digestive enzymes called zymogens into
3400-495: The back and front surfaces of the head of the pancreas adjacent to the duodenum. These supply the head of the pancreas. These vessels join together ( anastamose ) in the middle. The body and neck of the pancreas drain into the splenic vein , which sits behind the pancreas. The head drains into, and wraps around, the superior mesenteric and portal veins , via the pancreaticoduodenal veins . The pancreas drains into lymphatic vessels that travel alongside its arteries , and has
3485-536: The body, and an "exocrine" role, relating to the secretion of enzymes involved in digesting substances in the digestive tract. Cells within the pancreas help to maintain blood glucose levels ( homeostasis ). The cells that do this are located within the pancreatic islets that are present throughout the pancreas. When blood glucose levels are low, alpha cells secrete glucagon , which increases blood glucose levels. When blood glucose levels are high beta cells secrete insulin to decrease glucose in blood. Delta cells in
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3570-563: The body. The word pancreas comes from the Greek πᾶν (pân, "all") & κρέας (kréas, "flesh"). The function of the pancreas in diabetes has been known since at least 1889, with its role in insulin production identified in 1921. The pancreas is an organ that in humans lies in the abdomen , stretching from behind the stomach to the left upper abdomen near the spleen . In adults, it is about 12–15 centimetres (4.7–5.9 in) long, lobulated , and salmon-coloured in appearance. Anatomically,
3655-400: The creation of proteins, fats and carbohydrates. Insulin is initially created as a precursor form called preproinsulin . This is converted to proinsulin and cleaved by C-peptide to insulin which is then stored in granules in beta cells. Glucose is taken into the beta cells and degraded. The end effect of this is to cause depolarisation of the cell membrane which stimulates the release of
3740-549: The digestive action of the pancreas does not act to digest pancreatic tissue itself. These include the secretion of inactive enzymes (zymogens), the secretion of the protective enzyme trypsin inhibitor , which inactivates trypsin, the changes in pH that occur with bicarbonate secretion that stimulate digestion only when the pancreas is stimulated, and the fact that the low calcium within cells causes inactivation of trypsin. The pancreas also secretes vasoactive intestinal peptide and pancreatic polypeptide . Enterochromaffin cells of
3825-415: The digestive role of the pancreas, enzyme replacement may be needed to prevent malabsorption . Pancreatic cancers , particularly the most common type, pancreatic adenocarcinoma , remain very difficult to treat, and are mostly diagnosed only at a stage that is too late for surgery, which is the only curative treatment. Pancreatic cancer is rare in people younger than 40 and the median age of diagnosis
3910-461: The duodenum from the stomach. Inflammation of the pancreas is known as pancreatitis , with common causes including chronic alcohol use and gallstones . Because of its role in the regulation of blood sugar, the pancreas is also a key organ in diabetes mellitus . Pancreatic cancer can arise following chronic pancreatitis or due to other reasons, and carries a very poor prognosis, as it is often only identified after it has spread to other areas of
3995-421: The duodenum is encircled by the pancreas. This may be associated with duodenal atresia . 10,000 protein coding genes (~50% of all human genes) are expressed in the normal human pancreas. Less than 100 of these genes are specifically expressed in the pancreas. Similar to the salivary glands , most pancreas-specific genes encode for secreted proteins. Corresponding pancreas-specific proteins are either expressed in
4080-516: The enzyme enterokinase present in the lining of the duodenum. The proenzymes are cleaved, creating a cascade of activating enzymes. These enzymes are secreted in a fluid rich in bicarbonate . Bicarbonate helps maintain an alkaline pH for the fluid, a pH in which most of the enzymes act most efficiently, and also helps to neutralise the stomach acids that enter the duodenum. Secretion is influenced by hormones including secretin , cholecystokinin , and VIP , as well as acetylcholine stimulation from
4165-402: The ethical analysis. This situation continues as long as transplantation relies upon organ donors rather than technological innovation, testing, and industrial manufacturing. The English word "organ" dates back to the twelfth century and refers to any musical instrument. By the late 14th century, the musical term's meaning had narrowed to refer specifically to the keyboard-based instrument . At
4250-435: The exocrine cellular compartment and have functions related to digestion or food uptake such as digestive chymotrypsinogen enzymes and pancreatic lipase PNLIP , or are expressed in the various cells of the endocrine pancreatic islets and have functions related to secreted hormones such as insulin , glucagon , somatostatin and pancreatic polypeptide . The pancreas forms during development from two buds that arise from
4335-546: The exocrine pancreas damage the structure and tissue of the pancreas. Detection of some of these enzymes, such as amylase and lipase in the blood, along with symptoms and findings on medical imaging such as ultrasound or a CT scan , are often used to indicate that a person has pancreatitis. Pancreatitis is often managed medically with pain relief , and monitoring to prevent or manage shock, and management of any identified underlying causes. This may include removal of gallstones, lowering of blood triglyceride or glucose levels,
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#17327876403064420-568: The exocrine pancreas differentiate through molecules that induce differentiation including follistatin , fibroblast growth factors , and activation of the Notch receptor system. Development of the exocrine acini progresses through three successive stages. These are the predifferentiated, protodifferentiated, and differentiated stages, which correspond to undetectable, low, and high levels of digestive enzyme activity, respectively. Pancreatic progenitor cells differentiate into endocrine islet cells under
4505-553: The functional tissue, and stroma , the structural tissue with supportive, connective, or ancillary functions. For example, the gland 's tissue that makes the hormones is the parenchyma , whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the connective tissues that provide a suitable place for it to be situated and anchored. The main tissues that make up an organ tend to have common embryologic origins, such as arising from
4590-404: The head of the pancreas and the lesser curvature of the duodenum. They then join ( anastomose ) with the anterior and posterior branches of the superior pancreaticoduodenal artery . The inferior pancreaticoduodenal artery may branch from the first intestinal branch of the superior mesenteric artery rather than directly from it. The inferior pancreaticoduodenal artery distributes branches to
4675-509: The head of the pancreas and to the ascending and inferior parts of the duodenum . Very rarely, the inferior pancreaticoduodenal artery may have an aneurysm . It may be caused by certain medical interventions , major trauma , pancreatitis , cholecystitis , and vasculitis and other infections . A ruptured aneurysm causes abdominal pain , and haemorrhage leads to hypotension . It may be treated with open abdominal surgery . It may also be treated with endovascular surgery , such as
4760-451: The hormones secreted by the cells to enter the systemic circulation . The size of the pancreas varies considerably. Several anatomical variations exist, relating to the embryological development of the two pancreatic buds . The pancreas develops from these buds on either side of the duodenum. The ventral bud rotates to lie next to the dorsal bud , eventually fusing. In about 10% of adults, an accessory pancreatic duct may be present if
4845-459: The influence of neurogenin-3 and ISL1 , but only in the absence of notch receptor signaling . Under the direction of a Pax gene , the endocrine precursor cells differentiate to form alpha and gamma cells. Under the direction of Pax-6 , the endocrine precursor cells differentiate to form beta and delta cells. The pancreatic islets form as the endocrine cells migrate from the duct system to form small clusters around capillaries . This occurs around
4930-496: The insulin. The main factor influencing the secretion of insulin and glucagon are the levels of glucose in blood plasma. Low blood sugar stimulates glucagon release, and high blood sugar stimulates insulin release. Other factors also influence the secretion of these hormones. Some amino acids , that are byproducts of the digestion of protein , stimulate insulin and glucagon release. Somatostatin acts as an inhibitor of both insulin and glucagon. The autonomic nervous system also plays
5015-517: The islet also secrete somatostatin which decreases the release of insulin and glucagon. Glucagon acts to increase glucose levels by promoting the creation of glucose and the breakdown of glycogen to glucose in the liver. It also decreases the uptake of glucose in fat and muscle. Glucagon release is stimulated by low blood glucose or insulin levels, and during exercise. Insulin acts to decrease blood glucose levels by facilitating uptake by cells (particularly skeletal muscle ), and promoting its use in
5100-468: The liver and heart evolved in the chordates about 550-500 million years ago, while the gut and brain are even more ancient, arising in the ancestor of vertebrates, insects, molluscs, and worms about 700–650 million years ago. Given the ancient origin of most vertebrate organs, researchers have looked for model systems, where organs have evolved more recently, and ideally have evolved multiple times independently. An outstanding model for this kind of research
5185-409: The main duct of the dorsal bud of the pancreas does not regress; this duct opens into the minor duodenal papilla . If the two buds themselves, each having a duct, do not fuse, a pancreas may exist with two separate ducts, a condition known as a pancreas divisum . This condition has no physiologic consequence. If the ventral bud does not fully rotate, an annular pancreas may exist, where part or all of
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#17327876403065270-420: The main pancreatic duct. Usually, the duct of the dorsal bud regresses, leaving the main pancreatic duct . Pancreatic progenitor cells are precursor cells that differentiate into the functional pancreatic cells, including exocrine acinar cells, endocrine islet cells, and ductal cells. These progenitor cells are characterised by the co-expression of the transcription factors PDX1 and NKX6-1 . The cells of
5355-426: The middle of the acinus accumulate in intralobular ducts , which drain to the main pancreatic duct , which drains directly into the duodenum . About 1.5–3 liters of fluid are secreted in this manner every day. The cells in each acinus are filled with granules containing the digestive enzymes. These are secreted in an inactive form termed zymogens or proenzymes. When released into the duodenum, they are activated by
5440-434: The most common types. For those with neuroendocrine cancers the number alive after five years is much better at 65%, varying considerably with type. A solid pseudopapillary tumour is a low-grade malignant tumour of the pancreas of papillary architecture that typically afflicts young women. Diabetes mellitus type 1 is a chronic autoimmune disease in which the immune system attacks the insulin-secreting beta cells of
5525-467: The new generation of plants (see clonal colony ). Many societies have a system for organ donation , in which a living or deceased donor's organ are transplanted into a person with a failing organ. The transplantation of larger solid organs often requires immunosuppression to prevent organ rejection or graft-versus-host disease . There is considerable interest throughout the world in creating laboratory-grown or artificial organs . Beginning in
5610-520: The number alive at five years is approximately 20%. There are several types of pancreatic cancer, involving both the endocrine and exocrine tissue. The many types of pancreatic endocrine tumors are all uncommon or rare, and have varied outlooks. However the incidence of these cancers has been rising sharply; it is not clear to what extent this reflects increased detection, especially through medical imaging , of tumors that would be very slow to develop. Insulinomas (largely benign) and gastrinomas are
5695-403: The opposing sides. Aristotle used the word frequently in his philosophy, both to describe the organs of plants or animals (e.g. the roots of a tree, the heart or liver of an animal) because, in ancient Greek, the word ' organon ' means 'tool', and Aristotle believed that the organs of the body were tools for us by means of which we can do things. For similar reasons, his logical works, taken as
5780-406: The opposing sides. The organ level of organisation in animals can be first detected in flatworms and the more derived phyla , i.e. the bilaterians . The less-advanced taxa (i.e. Placozoa , Porifera , Ctenophora and Cnidaria ) do not show consolidation of their tissues into organs. More complex animals are composed of different organs, which have evolved over time. For example,
5865-514: The organ that bears the reproductive structures is called a cone . In other divisions ( phyla ) of plants, the reproductive organs are called strobili , in Lycopodiophyta , or simply gametophores in mosses . Common organ system designations in plants include the differentiation of shoot and root. All parts of the plant above ground (in non- epiphytes ), including the functionally distinct leaf and flower organs, may be classified together as
5950-409: The pancreas is divided into a head , neck , body , and tail . The pancreas stretches from the inner curvature of the duodenum , where the head surrounds two blood vessels : the superior mesenteric artery and vein . The longest part of the pancreas, the body, stretches across behind the stomach, and the tail of the pancreas ends adjacent to the spleen . Two ducts, the main pancreatic duct and
6035-549: The pancreas secrete the hormones motilin , serotonin , and substance P . It has been demonstrated that pancreatic tissue is a strong accumulator and secretor in the intestine of radioactive cesium ( Cs-137 ). Inflammation of the pancreas is known as pancreatitis . Pancreatitis is most often associated with recurrent gallstones or chronic alcohol use, with other common causes including traumatic damage, damage following an ERCP , some medications, infections such as mumps and very high blood triglyceride levels . Acute pancreatitis
6120-402: The pancreas sits the transverse colon. The pancreas narrows towards the tail, which sits near to the spleen. It is usually between 1.3–3.5 cm (0.51–1.38 in) long, and sits between the layers of the ligament between the spleen and the left kidney . The splenic artery and vein , which also passes behind the body of the pancreas, pass behind the tail of the pancreas. The pancreas has
6205-407: The pancreas, several medications act to enhance the secretion of insulin from beta cells, particularly sulphonylureas , which act directly on beta cells; incretins which replicate the action of the hormones glucagon-like peptide 1 , increasing the secretion of insulin from beta cells after meals, and are more resistant to breakdown; and DPP-4 inhibitors , which slow the breakdown of incretins. It
6290-423: The pancreas. Insulin is needed to keep blood sugar levels within optimal ranges, and its lack can lead to high blood sugar . As an untreated chronic condition, complications including accelerated vascular disease , diabetic retinopathy , kidney disease and neuropathy can result. In addition, if there is not enough insulin for glucose to be used within cells, the medical emergency diabetic ketoacidosis , which
6375-440: The peritoneum. Behind the pancreas are several blood vessels, including the aorta , the splenic vein , and the left renal vein , as well as the beginning of the superior mesenteric artery . Below the body of the pancreas sits some of the small intestine , specifically the last part of the duodenum and the jejunum to which it connects, as well as the suspensory ligament of the duodenum which falls between these two. In front of
6460-413: The relationship between the muscular and skeletal systems . In the study of anatomy , viscera ( sg. : viscus ) refers to the internal organs of the abdominal , thoracic , and pelvic cavities . The abdominal organs may be classified as solid organs or hollow organs . The solid organs are the liver , pancreas , spleen , kidneys , and adrenal glands . The hollow organs of the abdomen are
6545-534: The same germ layer . Organs exist in most multicellular organisms . In single-celled organisms such as members of the eukaryotes , the functional analogue of an organ is known as an organelle . In plants, there are three main organs. The number of organs in any organism depends on the definition used. There are approxiamately 79 Organs in the human body,but it is something that is debated as not all scientist agree on what counts as an organ. Except for placozoans , multicellular animals including humans have
6630-489: The same time, a second meaning arose, in reference to a "body part adapted to a certain function". Plant organs are made from tissue composed of different types of tissue. The three tissue types are ground, vascular, and dermal. When three or more organs are present, it is called an organ system. The adjective visceral , also splanchnic , is used for anything pertaining to the internal organs. Historically, viscera of animals were examined by Roman pagan priests like
6715-409: The shoot organ system. The vegetative organs are essential for maintaining the life of a plant. While there can be 11 organ systems in animals, there are far fewer in plants, where some perform the vital functions, such as photosynthesis , while the reproductive organs are essential in reproduction . However, if there is asexual vegetative reproduction , the vegetative organs are those that create
6800-430: The small intercalated ducts which they surround. In each acinus, the cells are pyramid-shaped and situated around the intercalated ducts, with the nuclei resting on the basement membrane , a large endoplasmic reticulum , and a number of zymogen granules visible within the cytoplasm . The intercalated ducts drain into larger intralobular ducts within the lobule, and finally interlobular ducts. The ducts are lined by
6885-462: The term "pancreas", a modern Latin adaptation of Greek πάγκρεας, [πᾶν ("all", "whole"), and κρέας ("flesh")], originally means sweetbread , although literally meaning all-flesh, presumably because of its fleshy consistency. It was only in 1889 when Oskar Minkowski discovered that removing the pancreas from a dog caused it to become diabetic. Insulin was later isolated from pancreatic islets by Frederick Banting and Charles Best in 1921. The way
6970-517: The third month of development, and insulin and glucagon can be detected in the human fetal circulation by the fourth or fifth month of development. The pancreas is involved in blood sugar control and metabolism within the body, and also in the secretion of substances (collectively pancreatic juice ) that help digestion. These are divided into an "endocrine" role, relating to the secretion of insulin and other substances within pancreatic islets that help control blood sugar levels and metabolism within
7055-550: The tissue of the pancreas has been viewed has also changed. Previously, it was viewed using simple staining methods such as H&E stains . Now, immunohistochemistry can be used to more easily differentiate cell types. This involves visible antibodies to the products of certain cell types, and helps identify with greater ease cell types such as alpha and beta cells. Pancreatic tissue is present in all vertebrates , but its precise form and arrangement varies widely. There may be up to three separate pancreases, two of which arise from
7140-422: The use of corticosteroids for autoimmune pancreatitis , and the cessation of any medication triggers. Chronic pancreatitis refers to the development of pancreatitis over time. It shares many similar causes, with the most common being chronic alcohol use, with other causes including recurrent acute episodes and cystic fibrosis . Abdominal pain, characteristically relieved by sitting forward or drinking alcohol,
7225-408: The ventral bud and the fusion of the two buds. During development, the duodenum rotates to the right, and the ventral bud rotates with it, moving to a position that becomes more dorsal. Upon reaching its final destination, the ventral pancreatic bud is below the larger dorsal bud, and eventually fuses with it. At this point of fusion, the main ducts of the ventral and dorsal pancreatic buds fuse, forming
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