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Introduction: The pancreas is a fish-shaped spongy grayish-pink organ about 6 inches

long, narrow gland that is situated transversely across the upper abdomen, behind the

stomach and the spleen. The mid portion of the pancreas lies against the vertebral

column, the abdominal aorta, and the inferior vena cava.The pancreas makes pancreatic

 juices and hormones, including insulin. The pancreatic juices are enzymes that help

digest food in the small intestine. Insulin controls the amount of sugar in the blood. As

 pancreatic juices are made, they flow into the main pancreatic duct. This duct joins the

common bile duct, which connects the pancreas to the liver and the gallbladder. The

common bile duct, which carries bile helps digest fat, connects to the small intestine near 

the stomach. The pancreas is thus a compound gland. It is compound in the sense that it is

composed of both an exocrine (ductal) and endocrine (ductless) gland. The exocrine

tissue, called acinar tissue, produces important digestive enzyme precursors that are

transmitted into the small intestine, while the endocrine tissue (contained in the islets of 

Langerhans) produces at least two hormones (insulin and glucagon) that are important in

the regulation of carbohydrate metabolism.

2 What is the Pancreas?

The pancreas is called the "hidden organ" because it is located deep in the abdomen

 behind the stomach. About six to eight inches long in the adult, the organ contains thintubes that come together like the veins of a leaf. These tubes join to form a single opening

into the intestine that is located just beyond the stomach.

The pancreas produces juices and enzymes that flow through these tubes into the

intestine, where they mix with food. The enzymes digest fat, protein, and carbohydrates

so they can be absorbed by the intestine. Pancreatic juices, therefore, play an important

role in maintaining good health. The pancreas also produces insulin, which is picked up

 by the blood flowing through the organ. Insulin is important in regulating the amount of 

sugar or glucose in the blood.

3. The location of pancreas: The pancreas is a gland about 6 inches long that is shaped

like a thin pear lying on its side. It is located posterior to the abdomen and lies behind the

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stomach and liver and in front of the spine. It has three areas: head (the wider end of the

 pancreas), body (the middle section), and tail (the narrow end). The pancreatic head

adjoins the second part of the duodenum while the tail extends towards the spleen. The

 pancreatic duct runs the length of the pancreas and empties into the second part of the

duodenum at the ampulla of Vater. The common bile duct commonly joins the pancreatic

duct at or near this point.

4. Physiologic Anatomy of Pancreas: The pancreas is several hundred thousand clusters

of cells called islets of Langerhans. The islets are endocrine tissue containing four types

of cells. In order of abundance, they are the:

•

 beta cells, which secrete insulin and amylin;• alpha cells, which secrete glucagon;• delta cells, which secrete somatostatin, and

• gamma cells, which secrete a polypeptide of unknown function.

Beta Cells

a. Insulin

Insulin is a small protein consisting of 

•

an alpha chain of 21 amino acids linked by two disulfide (S—S) bridges to a• Beta chain of 30 amino acids.

Beta cells have channels in their plasma membrane that serve as glucose detectors. Beta

cells secrete insulin in response to a rising level of circulating glucose ("blood sugar").

Insulin affects many organs. It

• stimulates skeletal muscle fibers to

o take up glucose and convert it into glycogen;

o take up amino acids from the blood and convert them into protein.

•

acts on liver cellso stimulating them to take up glucose from the blood and convert it into

glycogen whileo inhibiting production of the enzymes involved in breaking glycogen back 

down ("glycogenolysis") and

o inhibiting "gluconeogenesis"; that is, the conversion of fats and proteins

into glucose.

• acts on fat cells to stimulate the uptake of glucose and the synthesis of fat.

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• acts on cells in the hypothalamus to reduce appetite.

In each case, insulin triggers these effects by binding to the insulin receptor — a

transmembrane protein embedded in the plasma membrane of the responding cells.

Taken together, all of these actions result in:

• the storage of the soluble nutrients absorbed from the intestine into insoluble,energy-rich products (glycogen, protein, fat)

• a drop in the level of blood sugar 

b. Amylin

Amylin is a peptide of 37 amino acids, which is also secreted by the beta cells of the

 pancreas.

Some of its actions:

• inhibits the secretion of glucagon;

• slows the emptying of the stomach;

• Sends a satiety signal to the brain.

All of its actions tend to supplement those of insulin, reducing the level of glucose in the

 blood.

Alpha Cells

The alpha cells of the islets secrete glucagon, a polypeptide of 29 amino acids.

Glucagon acts principally on the liver where it stimulates the conversion of 

• glycogen into glucose ("glycogenolysis") and• fat and protein into intermediate metabolites that are ultimately converted into

glucose ("gluconeogenesis")

In both cases, the glucose is deposited in the blood.

Glucagon secretion is

• stimulated by low levels of glucose in the blood;• inhibited by high levels, and

• inhibited by amylin.

The physiological significance of this is that glucagon functions to maintain a steady

level of blood sugar level between meals.

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Delta Cells

Delta cells secrete somatostatin. This consists of two polypeptides, one of 14

amino acids and one of The 28.

Somatostatin has a variety of functions. Taken together, they work to reduce the

rate at which food is absorbed from the contents of the intestine.

Somatostatin is also secreted by the hypothalamus and by the intestine. Further 

information about somatostatin can be found by following the links.

Gamma Cells

The gamma cells of the islets secrete a 36-amino-acid pancreatic polypeptide, which

reduces appetite.

5.The hormone is secreted by pancreas: The pancreas folds under the stomach, secretes

the hormones insulin, glucagon, and somatostatin. About 70% of the pancreatic hormone-

secreting cells are called beta cells and secrete insulin; another 22%, or so, are called

alpha cells and secrete glucagon. The remaining gamma cells secrete somatostatin, also

known as growth hormone inhibiting hormone (GHIH). The alpha, beta, and gamma cells

comprise the islets of Langerhans which are scattered throughout the pancreas.

The Islands of Langerhans secrete four hormones insulin, glucagon, somatostatin and pancreatic polypeptide. Insulin and glucagon have antagonistic effects on the blood

glucose level.

Insulin: (Latin insula, "island", as it is produced in the Islets of Langerhans in the pancreas) is a polypeptide hormonethat regulates carbohydrate metabolism. Apart

from being the primary effectors in carbohydrate homeostasis, it also takes part in

the metabolism of fat (triglycerides) and proteins  – it has anabolic properties. Italso affects other tissues.

 

Glucagon: It is a amino acid  polypeptide hormone. Glucagon is a hormone with

the opposite action to insulin. It is made in the pancreas and is involved incarbohydrate metabolism. It is released when blood glucose levels start to fall

 below a threshold level and triggers the liver to convert stored glycogen into

glucose and release it into the bloodstream, raising blood glucose levels and so preventing hypoglycemia.

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Somatostatin: It helps inhibit the release of insulin and glucagon. In addition, it

also slows absorption of nutrients in the small intestine.

Pancreatic polypeptide

This pancreatic hormone prevents secretion of somatostatin by the pancreas. Also, pancreatic polypeptide inhibits contraction of the gallbladder wall and secretion of 

digestive enzymes by the pancreas.

6. The chemistry of pancreas hormons: The main pancreas hormons are insulin and

glucagon. The chemistry of these hormons are as bellow-

a. The chemistry of insulin: Insulin has the empirical formula C254H377 N65O75S6

Insulin structure varies slightly between species. Its carbohydrate metabolism

regulatory function strength also varies. Pig insulin is particularly close to the

human. The structure of insulin is below-

C254H377 N65O75S6

 b. The chemistry of Glucagon: Glucagon is a 29 amino acid  polypeptide acting as

an important hormone in carbohydrate metabolism. The polypeptide has amolecular weight of 3485 daltons and was discovered in 1923 by Kimball and

Murlin.

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Its primary structure is:

 NH2-His-Ser-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Lys-Tyr-Leu-Asp-Ser-Arg-

Arg-Ala-Gln-Asp-Phe-Val-Gln-Trp-Leu-Met-Asn-Thr-COOH

The structure of glucagon is below-

7. The synthesis of Pancreatic hormones: Glucagon and insulin are peptide hormones

released from the pancreas into the blood, that normally act in complementary fashion to

stabilize blood glucose concentration. The synthesis of insulin and glucagon hormon are

discribed as below-

Synthesis of insulin: Insulin is synthesized in significant quantities only in beta cells in

the pancreas. The insulin mRNA is translated as a single chain precursor called

 preproinsulin, and removal of its signal peptide during insertion into the endoplasmic

reticulum generates proinsulin.

Proinsulin consists of three domains: an amino-terminal B chain, a carboxy- terminal

A chain and a connecting peptide in the middle known as the C peptide. Within the

endoplasmic reticulum, proinsulin is exposed to several specific endopeptidases which

excise the C peptide, thereby generating the mature form of insulin. Insulin and free C

 peptide are packaged in the Golgi into secretory granules which accumulate in the

cytoplasm.

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When the beta cell is appropriately stimulated, insulin is secreted from the cell by

exocytosis and diffuses into islet capillary blood. C peptide is also secreted into

 blood, but has no known biological activity.

The secreton of insulin

Synthesis of glucagon: n L cells of the intestine the transcription factors TCF-4 and

Beta-catenin form a heterodimer and bind the G2 enhancer of the Proglucagon gene

GCG, activating its transcription to yield Proglucagon mRNA and, following translation,

Proglucagon protein. The prohormone convertase PC1 present in the secretory granules

of L cells cleaves Proglucagon at two sites to yield mostly Glucagon-like Peptide-1 with

a small amount of Glucagon-like Peptide-1 Glucagon-like Peptide is secreted into the

 bloodstream in response to glucose, fatty acids, insulin, leptin, gastrin-releasing peptide,

cholinergic transmitters, beta-adrenergic transmitters, and peptidergic transmitters. The

half-life of GLP-1 in the bloodstream is determined by Dipeptidyl Peptidase IV, which

cleaves 2 amino acids at the amino terminus of GLP-1, rendering it biologically inactive.

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synthesis of glucagon

8.The functin of Pancreatic hormons: The function of Pancreatic hormons are below

A. Insulin:

I. The function of insulin on the global human metabolism level include:

o cellular intake of certain substances, most prominently glucose 

o increase of DNA replication and protein synthesis 

o modification of the activity of numerous enzymes 

II. The function of insulin on cells include:

o Increased glycogen synthesis – insulin forces storage of glucose in liver 

(and muscle) cells in the form of glycogen; lowered levels of insulin cause

liver cells to convert glycogen to glucose and excrete it into the blood.

This is the clinical action of insulin which is useful in reducing high blood

glucose levels in diabetes.

o increased fatty acid synthesis – insulin forces fat cells to take in glucose

which is converted to fatty acids; lack of insulin causes the reverse

o increased esterification of fatty acids – forces adipose tissue to make fats

(ie, triglycerides) from fatty acid esters; lack of insulin causes the reverseo decreased proteinolysis – forces reduction of protein degradation; lack of 

insulin increases protein degradation,

o decreased lipolysis – forces reduction in conversion of fat cell lipid stores

into blood fatty acids; lack of insulin causes the reverse

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o decreased gluconeogenesis – decreases production of glucose from various

substrates in liver; lack of insulin causes glucose production from assorted

substrates in the liver and elsewhere

o increased amino acid uptake – forces cells to absorb circulating amino

acids; lack of insulin inhibits absorption

o increased potassium uptake – forces cells to absorb serum potassium; lack 

of insulin inhibits absorption

o arterial muscle tone – forces arterial wall muscle to relax, increasing blood

flow, especially in micro arteries; lack of insulin reduces flow by allowing

these muscles to contract

B. Glucagon: Glucagon prevents the drop in blood glucose level (hypoglycemia),thereby helps in regulating blood-glucose level. Glucagon increases the blood

glucose level by any of the following processes:

o Glucagon is released when blood sugar levels drop too low. It stimulates the liver 

to convert glycogen to glucose, therefore increasing blood sugar levels. It is a

hormone agonist .

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o Its opposing hormone is insulin, an antagonist which is release when blood sugar 

levels climb too high.

o Glycogenolysis– breakdown of Glycogen. Glycogen is a polymer of glucose

stored in the liver. The liver cells (hepatocytes) contain glucagon receptors. Whenglucagon binds to these receptors, the liver cells break-down glycogen to glucosemonomers. The glucose is then released into the blood stream.

o Gluconeogenesis – synthesis of glucose from non-carbohydrate carbon substrates

such as glycerol, lactate, glucogenic amino acids.

o Lipolysis – hydrolysis of lipids. It involves catabolism of triglycerides to free

fatty acids and glycerol.

C. Somatostatin: The hormone somatostatin helps inhibit the release of insulin and

glucagon. In addition, it also slows absorption of nutrients in the small intestine.

9 The disorders of panreas: Diseases of the pancreas, benign tumors, Carcinoma of 

 pancreas, Cystic fibrosis, Diabetes, Pancreatitis, Acute pancreatitis,chronic pancreatitis,

 pancreatic pseudocyst etc

1. Acute pancreatitis:

Causes:

The most common cause of acute pancreatitis is the presence of gallstones—small,

 pebble-like substances made of hardened bile—that cause inflammation in the pancreas

as they pass through the common bile duct. Chronic, heavy alcohol use is also a common

cause. Acute pancreatitis can occur within hours or as long as 2 days after consuming

alcohol. Other causes of acute pancreatitis include abdominal trauma, medications,

infections, tumors, and genetic abnormalities of the pancreas.

Symptoms:

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Acute pancreatitis usually begins with gradual or sudden pain in the upper abdomen that

sometimes extends through the back. The pain may be mild at first and feel worse after 

eating. But the pain is often severe and may become constant and last for several days. A

 person with acute pancreatitis usually looks and feels very ill and needs immediate

medical attention. Other symptoms may include

o A swollen and tender abdomen

o  Nausea and vomiting

o Fever 

o A rapid pulse

Severe acute pancreatitis may cause dehydration and low blood pressure. The heart,

lungs, or kidneys can fail. If bleeding occurs in the pancreas, shock and even death may

follow.

Chronic pancreatitis:

Causes:

The most common cause of chronic pancreatitis is many years of heavy alcohol use. Thechronic form of pancreatitis can be triggered by one acute attack that damages the

 pancreatic duct. The damaged duct causes the pancreas to become inflamed. Scar tissue

develops and the pancreas is slowly destroyed.

Other causes of chronic pancreatitis are

o Hereditary disorders of the pancreas

o Cystic fibrosis—the most common inherited disorder leading to chronic

 pancreatitis

o Hypocalcaemia—high levels of calcium in the blood

o Hyperlipidemia or hypertriglyceridemia—high levels of blood fats

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Symptoms:

Most people with chronic pancreatitis experience upper abdominal pain, although some

 people have no pain at all. The pain may spread to the back, feel worse when eating or 

drinking, and become constant and disabling. In some cases, abdominal pain goes away

as the condition worsens, most likely because the pancreas is no longer making digestive

enzymes. Other symptoms include

o  Nausea

o Vomiting

o Weight loss

o Diarrhea

Treatment:

Treatment for chronic pancreatitis may require hospitalization for pain management, IV

hydration, and nutritional support. Nasogastric feedings may be necessary for several

Gallstones:

Causes:

o Gallstones occur when bile forms solid particles (stones) in the gallbladder.

o The stones form when the amount of cholesterol or bilirubin in the bile is high.

o Other substances in the bile may promote the formation of stones.

o Pigment stones form most often in people with liver disease or blood disease, who

have high levels of bilirubin.

o Poor muscle tone may keep the gallbladder from emptying completely. The

 presence of residual bile may promote the formation of gallstones.

Gallstones Symptoms:

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Common symptoms of gallstones include the following:

o  Nausea and vomiting,fever,

o Indigestion, belching, bloating,

o Intolerance for fatty or greasy foods, and

o Jaundice (yellowing of the skin or the whites of the eyes).

o Warning signs of a serious problem are fever, jaundice, and persistent pain

Pancreatic Cancer:

Causes:

The main recognized risk factors for pancreatic cancer include the following:

o Smoking

o Advanced age

o Male sex - The male-to-female ratio of pancreatic cancer is 1.3:1.

o Chronic pancreatitis - Inflammation of the pancreas, usually from excessive

alcohol intake or gallstones

o Diabetes mellitus

Pancreatic Cancer Symptoms:

The main symptoms of pancreatic cancer include the following:

o

Pain in the abdomen, the back, or both

o Weight loss, often associated with the following:

o Loss of appetite (anorexia)

o Bloating

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o Diarrhea or fatty bowel movements that float in water (steatorrhea)

o Rarely may present with new diabetes in a person with weight loss and nausea

o Jaundice (yellowing of the skin)

Pancreatic Cancer Treatment:

The optimal treatment of pancreatic Aden carcinoma depends on the extent of the

disease. The extent of cancer can be divided into the following 3 categories:

o Localized: The cancer is completely confined within the pancreas.

o Locally advanced: The cancer has extended from the pancreas to involve nearby

 blood vessels or organs.

o Metastatic: The cancer has spread outside the pancreas to other parts of the body.

Tumor of pancears:

An islet cell tumor may also be called a pancreatic endocrinetumor (PET), pancreatic

neuroendocrine tumor, islet cell carcinoma, or pancreatic carcinoid.Islet cell tumors may

or may not cause symptoms.

There are different kinds of functional islet cell tumors.

Islet cells make different kinds of hormones such as gastrin, insulin, and glucagon. Types

of functional islet cell tumors include the following:

o Gastrinoma: A tumor that forms in cells that make gastrin. Gastrin is a hormone

that causes the stomach to release an acid that helps digest food. Both gastrin and

stomach acid are increased by gastrinomas. When increased stomach acid,

stomach ulcers, and diarrhea are caused by a tumor that makes gastrin, it is called

Zollinger-Ellison syndrome. A gastrinoma usually forms in the head of the

 pancreas and sometimes forms in the small intestine. Most gastrinomas are

malignant (cancer).

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o Insulnoma: A tumor that forms in cells that make insulin. Insulin is a hormone

that controls the amount of glucose (sugar) in the blood. It moves glucose into the

cells, where it can be used by the body for energy. Insulinomas are usually slow-

growing tumors that rarely spread. An insulinoma forms in the head, body, or tail

of the pancreas. Insulinomas are usually benign (not cancer).

o Glucagonoma: A tumor that forms in cells that make glucagon. Glucagon is a

hormone that increases the amount of glucose in the blood. It causes the liver to

 break down glycogen. Too much glucagon causes hyperglycemia (high blood

sugar). Glucagonomas are often malignant. A glucagonoma usually forms in the

tail of the pancreas. Most glucagonomas are malignant (cancer).

o Other type of tumors: There are other rare types of functional islet cell tumors

that make hormones, including hormones that control the balance of sugar, salt,

and water in the body. These tumors include:

o VIPomas, which make vasoactive intestinal peptide. VIPoma may also be called

Verner-Morrison syndrome.

o Somatostatinomas, which make somatostatin.

10. Conclution: After all we can say pancreas is an important organ in our body .The

 pancreas produces the body's most important enzymes. The enzymes are designed to

digest foods and break down starches. The pancreas also helps neutralize chyme and

helps break down proteins, fats and starch. Chyme is a thick semifluid mass of partly

digested food that is passed from the stomach to the duodenum. If the pancreas is not

working properly to neutralize chyme and break down proteins, fats and starch, starvation

may occur. The pancreas is vital to good health. It is subject to a variety of problems,

some of which result from the patient's own actions. There are now effective ways to

diagnose pancreatic conditions and, in most cases, good treatment programs can be

outlined by the physician.

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Reference

http://digestive.niddk.nih.gov/ddiseases/pubs/pancreatitis

http://endocrinehealth.blogspot.com/2009/05/hormones-produced-by-

 pancreas.html

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Pancreas.html

http://www.gicare.com/diseases/Pancreatic-Disease.aspx

http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/insulin.html

http://www.emedicinehealth.com/pancreatic_cancer/page3_em.htm

http://www.gicare.com/diseases/Pancreatic-Disease.aspx

http://www.medicinenet.com/pancreas_divisum/page2.htm

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