Pancreas

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Pancreas

The pancreas is a gland

Gland

A gland is an Organ in an animal's body that synthesizes a substance for release such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface ....
organ

Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
in the digestive and endocrine system

Endocrine system

The endocrine system is a system of small organs that involve the release of extracellular signaling molecules known as hormones. The endocrine system is instrumental in regulating metabolism, human development , and tissue and also plays a part in determining Mood ....
of vertebrate

Vertebrate

Vertebrates are members of the subphylum Vertebrata, chordates with Vertebras or Vertebral columns. The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lampreys, which do have vertebrae....
s. It is both an endocrine gland (producing several important hormone

Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s, including insulin

Insulin

Insulin is a hormone with extensive effects on both metabolism and several other body systems . Insulin causes most of the body's cells to take up glucose from the blood , storing it as glycogen in the liver and muscle, and stops use of fat as an energy source....
, glucagon

Glucagon

Glucagon is an important hormone involved in carbohydrate metabolism. Produced by the pancreas, it is released when the glucose level in the blood is low , causing the liver to convert stored glycogen into glucose and release it into the bloodstream....
, and somatostatin

Somatostatin

Somatostatin is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G-protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones....
), as well as an exocrine gland

Exocrine gland

Exocrine glands are glands that secrete their products into duct s . They are the counterparts to endocrine glands, which secrete their products directly into the bloodstream or release hormones that affect only target cells nearby the release site....
, secreting pancreatic juice

Pancreatic juice

Pancreatic juice is a liquid secreted by the pancreas, which contains a variety of enzymes, including trypsinogen, chymotrypsinogen, elastase, carboxypeptidase, pancreatic lipase, and amylase....
containing digestive

Digestion

Digestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be Absorption, for instance, by a blood stream....
enzyme

Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s that pass to the small intestine

Small intestine

In vertebrates, including mammals, reptiles, birds, and bony fish, the small intestine is the part of the gastrointestinal tract following the stomach, and is where the vast majority of digestion takes place....
. These enzymes help in the further breakdown of the carbohydrates, protein

Protein

Proteins are organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid Residue ....
, and fat

Fat

Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemistry, fats are generally ester of glycerol and fatty acids....
in the chyme

Chyme

Chyme is the semifluid mass of partly digested food expelled by the stomach into the duodenum. In other words, chyme is half digested food. Also known as Chymus, it is the liquid substance found in the stomach before passing through the pyloric valve and entering the duodenum....
.

r a microscope

Microscope

A microscope is an Laboratory equipment for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy....
, stained sections of the pancreas reveal two different types of parenchyma

Parenchyma

Parenchyma is a term used to describe a bulk of a substance. It is used in different ways in animals and in plants.The term is New Latin, from Greek language parenkhuma, visceral flesh, from parenkhein, to pour in beside : para-, beside + en-, in + khein, to pour....
l tissue.

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Encyclopedia

The pancreas is a gland

Gland

Organ (anatomy)

Endocrine system

Vertebrate

Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s, including insulin

Insulin

Glucagon

Somatostatin

Exocrine gland

Pancreatic juice

Digestion

Digestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be Absorption, for instance, by a blood stream....
enzyme

Enzyme

Small intestine

Protein

Fat

Chyme

Histology

Under a microscope

Microscope

Parenchyma

Islets of Langerhans

Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s that underlie the endocrine functions of the pancreas. Darker staining cells form acini

Acinus

An acinus refers to the berry-shaped termination of an exocrine gland, where the secretion is produced.They are found in many organs, including:...
connected to ducts. Acinar cells belong to the exocrine pancreas

Exocrine pancreas

The exocrine pancreas has ducts that are arranged in clusters called acini . Pancreatic secretions are secreted into the lumen of the acinus, and then accumulate in intralobular ducts that drain to the main pancreatic duct, which drains directly into the duodenum....
and secrete digestive enzyme

Digestive enzyme

Digestion enzymes are enzymes that break down polymeric macromolecules into their smaller building blocks. Digestive enzymes are found in the digestive tract of animals or humans where they aid in the digestion of food as well as inside cell , especially in their lysosomes....
s into the gut via a system of ducts.

Structure	Appearance	Function
Islets of Langerhans Islets of Langerhans The islets of Langerhans are the regions of the pancreas that contain its endocrine cells. Discovered in 1869 by German pathological anatomist Paul Langerhans, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas....	Lightly staining, large, spherical clusters	Hormone Hormone Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism.... production and secretion (endocrine pancreas)
Pancreatic acini Exocrine pancreas The exocrine pancreas has ducts that are arranged in clusters called acini . Pancreatic secretions are secreted into the lumen of the acinus, and then accumulate in intralobular ducts that drain to the main pancreatic duct, which drains directly into the duodenum....	Darker staining, small, berry-like clusters	Digestive enzyme Digestive enzyme Digestion enzymes are enzymes that break down polymeric macromolecules into their smaller building blocks. Digestive enzymes are found in the digestive tract of animals or humans where they aid in the digestion of food as well as inside cell , especially in their lysosomes.... production and secretion (exocrine pancreas Exocrine pancreas The exocrine pancreas has ducts that are arranged in clusters called acini . Pancreatic secretions are secreted into the lumen of the acinus, and then accumulate in intralobular ducts that drain to the main pancreatic duct, which drains directly into the duodenum.... )

Function

The pancreas is a dual-function gland, having features of both endocrine and exocrine gland

Exocrine gland

Endocrine

The part of the pancreas with endocrine function is made up of a million cell clusters called islets of Langerhans

Islets of Langerhans

The islets of Langerhans are the regions of the pancreas that contain its endocrine cells. Discovered in 1869 by German pathological anatomist Paul Langerhans, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas....
. There are four main cell types in the islets. They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion: a cells secrete glucagon

Glucagon

Insulin

Somatostatin

Pancreatic polypeptide

Pancreatic polypeptide is a polypeptide secreted by PP cells in the endocrine pancreas predominantly in the head of the pancreas. It consists of 36 amino acids and has molecular weight about 4200 Dalton_%28unit%29....
.

The islets are a compact collection of endocrine cells arranged in clusters and cords and are crisscrossed by a dense network of capillaries. The capillaries of the islets are lined by layers of endocrine cells in direct contact with vessels, and most endocrine cells are in direct contact with blood vessels, by either cytoplasm

Cytoplasm

The cytoplasm is the part of a Cell that is enclosed within the plasma membrane. In eukaryote cells the cytoplasm contains organelles, such as mitochondrion, that are filled with liquid kept separate from the rest of the cytoplasm by biological membranes....
ic processes or by direct apposition. According to the volume The Body, by Alan E. Nourse

Alan E. Nourse

Alan Edward Nourse was an United States science fiction author and physician. He wrote both juvenile and adult science fiction, as well as nonfiction works about medicine and science....
, the islets are "busily manufacturing their hormone and generally disregarding the pancreatic cells all around them, as though they were located in some completely different part of the body."

Exocrine

In contrast to the endocrine pancreas, which secretes hormones into the blood, the exocrine pancreas produces digestive enzyme

Digestive enzyme

Small intestine

In vertebrates, including mammals, reptiles, birds, and bony fish, the small intestine is the part of the gastrointestinal tract following the stomach, and is where the vast majority of digestion takes place....
through a system of exocrine ducts in response to the small intestine hormones secretin

Secretin

Secretin is a peptide hormone produced in the S cells of the duodenum in the crypts of Lieberk?hn. Its primary effect is to regulate the pH of the duodenal contents via the control of gastric acid secretion and buffering with bicarbonate....
and cholecystokinin

Cholecystokinin

Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, previously called pancreozymin, is synthesised by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, the first segment of the small intestine, and ca...
. Digestive enzymes include trypsin

Trypsin

Trypsin is a serine protease found in the digestive system, where it breaks down proteins. Trypsin predominantly cleaves peptide chains at the carboxyl side of the amino acids lysine and arginine, except when either is followed by proline....
, chymotrypsin

Chymotrypsin

Chymotrypsin is a digestive enzyme that can perform proteolysis. Chymotrypsin cleaves peptides at the carboxyl side of tyrosine, tryptophan, and phenylalanine because these three amino acids contain aromatic rings, which fit into a 'hydrophobic pocket' in the enzyme....
, pancreatic lipase

Pancreatic lipase

Pancreatic lipase is an enzyme secreted from the pancreas that uses hydrolysis to break apart fat molecules. Bile salts secreted from the liver and stored in gallbladder are released into the duodenum where they coat and emulsify large fat droplets into smaller droplets, thus increasing the overall surface area of the fat, which allows the l...
, and pancreatic amylase, and are produced and secreted by acinar cell

Acinar cell

Acinar cell can refer to:exocrine cells of the pancreas, which release hydrolytic enzymes into the small intestine .* Centroacinar cells of the pancreas...
s of the exocrine pancreas. Specific cells that line the pancreatic ducts, called centroacinar cells, secrete a bicarbonate

Bicarbonate

In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid. Its chemical formula is HCO3−....
- and salt

Salt

A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and base . Salts are ionic compounds composed of cations and anions so that the product is electrically electric charge ....
-rich solution into the small intestine.

Regulation

The pancreas receives regulatory innervation via hormone

Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s in the blood and through the autonomic nervous system

Autonomic nervous system

The autonomic nervous system is the part of the peripheral nervous system that acts as a control system, maintaining human homeostasis in the body....
. These two inputs regulate the secretory activity of the pancreas.

Sympathetic

Sympathetic nervous system

The Sympathetic Nervous System is a branch of the autonomic nervous system along with the enteric nervous system and parasympathetic nervous system....
(adrenergic

Adrenergic

An adrenergic is a medication, or other substance, which has effects similar to, or the same as, epinephrine . Thus, they are a kind of sympathomimetic agents....
) >

Parasympathetic (muscarinic) \|- \| a2: decreases secretion from beta cell Beta cell Beta cells are a type of cell in the pancreas in areas called the islets of Langerhans. They make up 65-80% of the cells in the islets.... s, increases secretion from alpha cell Alpha cell Alpha cells are endocrine system cell s in the islets of Langerhans of the pancreas. They make up 15-20% of the cells in the islets. They are responsible for synthesizing and secreting the peptide hormone glucagon, which elevates the glucose levels in the blood.... s	M3 increases stimulation from alpha cell Alpha cell Alpha cells are endocrine system cell s in the islets of Langerhans of the pancreas. They make up 15-20% of the cells in the islets. They are responsible for synthesizing and secreting the peptide hormone glucagon, which elevates the glucose levels in the blood.... s and beta cell Beta cell Beta cells are a type of cell in the pancreas in areas called the islets of Langerhans. They make up 65-80% of the cells in the islets....

Diseases of the pancreas

Because the pancreas is a storage depot for digestive enzymes, injury to the pancreas is potentially very dangerous. A puncture of the pancreas generally requires prompt and experienced medical intervention.

An incision into the pancreas is known as a pancreatotomy.

History

The pancreas was first identified by Herophilus (335-280 BC), a Greek

Greeks

The Greeks , also known as Hellenes, are a nation and ethnic group native to Greece, Cyprus and neighbouring regions, who can also be found in Greek diaspora communities around the world....
anatomist and surgeon

Surgery

Surgery is a medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, to help improve bodily function or appearance, or sometimes for some other reason....
. Only a few hundred years later, Ruphos, another Greek anatomist, gave the pancreas its name. The term "pancreas" is derived from the Greek

Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
pan, "all", and kreas, "flesh", probably referring to the organ's homogeneous appearance.

Embryological development

The pancreas forms from the embryonic foregut

Foregut

The foregut is the anterior part of the alimentary canal, from the mouth to the duodenum at the entrance of the bile duct. At this point it is continuous with the midgut....
and is therefore of endoderm

Endoderm

Endoderm, is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron from the inner layer of the gastrula, which develops into the endoderm....
al origin. Pancreatic development begins the formation of a ventral and dorsal anlage (or buds). Each structure communicates with the foregut through a duct. The ventral pancreatic bud becomes the head and unciate process, and comes from the hepatic diverticulum.

Differential rotation and fusion of the ventral and dorsal pancreatic buds results in the formation of the definitive pancreas. As the duodenum rotates to the right, it carries with it the ventral pancreatic bud and common bile duct. Upon reaching its final destination, the ventral pancreatic bud fuses with the much larger dorsal pancreatic bud. At this point of fusion, the main ducts of the ventral and dorsal pancreatic buds fuse, forming the duct of Wirsung, the main pancreatic duct.

Differentiation of cells of the pancreas proceeds through two different pathways, corresponding to the dual endocrine and exocrine functions of the pancreas. In progenitor cells of the exocrine pancreas, important molecules that induce differentiation include follistatin

Follistatin

Follistatin is a single chain autocrine glycoprotein found to be ubiquitous within the body of nearly all higher animals, that is the product of a single gene....
, fibroblast growth factor

Fibroblast growth factor

Fibroblast growth factors, or FGFs, are a family of growth factors involved in angiogenesis, wound healing, and embryonic development. The FGFs are heparin-binding proteins and interactions with cell-surface associated heparan sulfate proteoglycans have been shown to be essential for FGF signal transduction....
s, and activation of the Notch receptor system. Development of the exocrine acini progresses through three successive stages. These include the predifferentiated, protodifferentiated, and differentiated stages, which correspond to undetectable, low, and high levels of digestive enzyme activity, respectively.

Progenitor cells of the endocrine pancreas arise from cells of the protodifferentiated stage of the exocrine pancreas. Under the influence of neurogenin-3 and Isl-1, but in the absence of Notch receptor signaling, these cells differentiate to form two lines of committed endocrine precursor cells. The first line, under the direction of Pax-6, forms a- and ?- cells, which produce the peptides glucagon

Glucagon

Pancreatic polypeptide

Pancreatic polypeptide is a polypeptide secreted by PP cells in the endocrine pancreas predominantly in the head of the pancreas. It consists of 36 amino acids and has molecular weight about 4200 Dalton_%28unit%29....
, respectively. The second line, influenced by Pax-4, produces ß- and d-cells, which secrete insulin

Insulin

Somatostatin

As food

The pancreas of lamb, beef, and pork is prepared and eaten. Along with the thymus, pancreas is considered a sweetbread

Sweetbread

File:Sweetbreads.jpgSweetbreads are the thymuss and pancreas glands of lamb and mutton, beef, or pork. There are two different connected parts to the thymus gland, both set in the neck....
.

Pancreas

Histology

Function

Endocrine

Exocrine

Regulation

Diseases of the pancreas

History

Embryological development

As food

Additional images