pancreas anatomy physiology n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Pancreas: Anatomy & Physiology PowerPoint Presentation
Download Presentation
Pancreas: Anatomy & Physiology

Loading in 2 Seconds...

play fullscreen
1 / 32

Pancreas: Anatomy & Physiology - PowerPoint PPT Presentation


  • 240 Views
  • Uploaded on

Pancreas: Anatomy & Physiology. Pancreas- Brief History. Pancreas – derived from the Greek pan, “all”, and kreas , “flesh”, probably referring to the organ’s homogenous appearance Herophilus , Greek anatomist and Surgeon, first identified the pancreas in 335 – 280 BC

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Pancreas: Anatomy & Physiology' - debra-spence


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
pancreas brief history
Pancreas- Brief History
  • Pancreas – derived from the Greek pan, “all”, and kreas, “flesh”, probably referring to the organ’s homogenous appearance
  • Herophilus, Greek anatomist and Surgeon, first identified the pancreas in 335 – 280 BC
  • Ruphos, another Greek anatomist, gave pancreas its name after few hundred years
  • Wirsung discovered the pancreatic duct in 1642.
  • Pancreas as a secretory gland was investigated by Graaf in 1671.
pancreas
Pancreas
  • Gland with both exocrine and endocrine functions
  • 6-10 inch in length (15-25 cm)
  • 60-100 gram in weight
  • Location: retro-peritoneum, 2nd lumbar vertebral level
  • Extends in an oblique, transverse position
  • Parts of pancreas: head, neck, body and tail
histology
Histology
  • There are two distinct organ systems within the pancreas
  • The endocrine portion of the pancreas is served by structures called the islet of Langerhans
    • The islet of Langerhans have several distinct cell types
      • Alpha cells-produce glucagon and constitute approximate 25% of the total islet cell number
      • Beta cells-the insulin producing cells (majority of the cells)
      • Delta cells-produce somatostatin (smallest number)
  • The exocrine portion of the pancreas is made up of acini and ductal systems
    • Acinar cells contain zymogen
anatomy
Anatomy
  • Is a retroperitoneal structure found posterior to the stomach and lesser omentum
  • It has a distinctive yellow/tan/pink color and is multilobulated
  • The gland is divided into four portions
    • The head
    • The neck
    • The body
    • The tail
  • The pancreas has an extensive arterial system arising from multiple sources
  • The venous drainage parallels arterial anatomy
    • The veins terminate in the portal vein
  • Multiple lymph nodes drain the pancreas
  • Neural function is controlled by duel sympathetic and parasympathetic innervation
head of pancreas
Head of Pancreas
  • Includes uncinate process: Lower part of the posterior surface of the head that wraps behind the superior mesenteric artery and superior mesenteric vein
  • Flattened structure, 2 – 3 cm thick
  • Attached to the 2nd and 3rd portions of duodenum on the right
  • Emerges into neck on the left
  • Border b/w head & neck is determined by GDA insertion
  • SPDA and IPDA anastamose b/w the duodenum and the rt. lateral border
  • Broadest part
  • Mouldedinto the C shaped concavity of duodenum
  • Lies over the inferior venacava, the right and left renal veins at the level of L2
  • Posterior surface is indented by the terminal part of the bile duct
neck of pancreas
Neck of Pancreas
  • 2.5 cm in length
  • Lies in front of the superior mesenteric and portal veins
  • Posteriorly, mostly no branches to pancreas
body of pancreas
Body of Pancreas
  • Elongated structure
  • Anterior surface, separated from stomach by lesser sac
  • Posterior surface, related to aorta, lt. adrenal gland, lt. renal vessels and upper 1/3rd of lt. kidney
  • Splenic vein runs embedded in the post. Surface
  • Inferior surface is covered by tran. Mesocolon
  • Body passes across the left renal vein and aorta, left crus of diaphragm, left psoas muscle, lower pole of left suprarenal gland to the hilum of left kidney
  • Upper border crosses the aorta at the origin of the celiac trunk
  • Splenic artery passes to the left along the upper border
  • Lower border crosses the origin of the superior mesenteric artery
tail of pancreas
Tail of Pancreas
  • Narrow, short segment
  • Lies at the level of the 12th thoracic vertebra
  • Lies in the lienorenal ligament along with splenic artery, vein, lymphatics
  • End of tail of pancreas touches the hilum of spleen
  • Anteriorly, close to splenic flexure of colon
  • May be injured during splenectomy (fistula)
  • Passes forward from the anterior surface of the left kidney at the level of hilum
pancreatic duct
Pancreatic Duct
  • Main duct (Duct of Wirsung) runs the entire length of pancreas
    • Joins Central Bile Duct at the ampulla of Vater
    • 2 – 4 mm in diameter, 20 secondary branches
  • Lesser duct (Duct of Santorini) drains superior portion of head and empties separately into 2nd portion of duodenum
    • Drains the uncinate process and lower part of head
pancreatic physiology
Pancreatic Physiology
  • Exocrine pancreas 85% of the volume of the gland
  • Extracellular matrix – 10%
  • Blood vessels and ducts - 4%
  • Endocrine pancreas – 1%
histology exocrine pancreas
Histology-Exocrine Pancreas
  • 2 major components
    • Acinar cells which secrete primarily digestive enzymes
    • Centroacinar or ductal cells which secrete fluids and electrolytes
  • Constitute 80% to 90% of the pancreatic mass
  • Acinar cells secrete the digestive enzymes
  • 20 to 40 acinar cells coalesce into a unit called the acinus
  • Centroacinar cell (2nd cell type in the acinus) is responsible for fluid and electrolyte secretion by the pancreas
  • Duct system - network of conduits that carry the exocrine secretions into the duodenum
histology endocrine pancreas
Histology-Endocrine Pancreas
  • Accounts for only 2% of the pancreatic mass
  • Nests of cells - islets of Langerhans
  • Four major cell types
    • Alpha (A) cells secrete glucagon
    • Beta (B) cells secrete insulin
    • Delta (D) cells secrete somatostatin
    • F cells secrete pancreatic polypeptide
histology endocrine pancreas1
Histology-Endocrine Pancreas
  • B cells are centrally located within the islet and constitute 70% of the islet mass
  • PP, A, and D cells are located at the periphery of the islet
physiology exocrine pancreas
Physiology – Exocrine Pancreas
  • Secretion of water and electrolytes originates in the centroacinarand intercalated duct cells
  • Pancreatic enzymes originate in the acinar cells
  • Final product is a colorless, odorless, and isosmotic alkaline fluid that contains digestive enzymes (amylase, lipase, and trypsinogen)
  • Alkaline pH results from secreted bicarbonate which serves to neutralize gastric acid and regulate the pH of the intestine
  • Enzymes digest carbohydrates, proteins, and fats
exocrine
Exocrine
  • The bulk of the pancreas is an exocrine gland secreting pancreatic fluid into the duodenum after a meal.
  • The principal stimulant of pancreatic water and electrolyte secretion – Secretin
  • Secretin is synthesized in the S cells of the crypts of Liberkuhn
  • Released into the blood stream in the presence of luminal acid and bile
bicarbonate secretion
Bicarbonate Secretion
  • Bicarbonate is formed from carbonic acid by the enzyme carbonic anhydrase
  • Major stimulants

Secretin, Cholecystokinin, Gastrin, Acetylcholine

  • Major inhibitors

Atropine, Somatostatin, Pancreatic polypeptide and Glucagon

  • Secretin - released from the duodenal mucosa in response to a duodenal luminal pH < 3
enzymes types and secretion
Enzymes: Types and Secretion
  • Amylase
    • only digestive enzyme secreted by pancreas in active form
    • hydrolyzes starch and glycogen to glucose, maltose, maltotriose, and dextrins
  • Lipase
    • emulsify and hydrolyze fat in the presence of bile salts
  • Proteases
    • essential for protein digestion
    • secreted as proenzymes; require activation for proteolytic activity
    • duodenal enzyme, enterokinase, converts trypsinogen to trypsin
    • Trypsin, in turn, activates chymotrypsin, elastase, carboxypeptidase, and phospholipase
  • Released from the acinar cells into the lumen of the acinus and then transported into the duodenal lumen, where the enzymes are activated.
  • Ultimate result of all these actions is food digestion and absorption
physiology endocrine pancreas
Physiology – Endocrine Pancreas
  • Principal function is to maintain glucose homeostasis
  • Insulin and glucagon play a major role in glucose homeostasis
  • In addition endocrine pancreas secrete somatostatin, pancreatic polypeptide, c peptide, & amylin
  • pancreatic polypeptide – released internally to self-regulate pancreas activities
  • amylin – released with insulin; contributes to glycemic control
insulin
Insulin
  • Synthesized in the beta cells of the islets of Langerhans
  • 80% of the islet cell mass must be surgically removed before diabetes becomes clinically apparent
  • Insulin and C peptide are packaged into secretory granules and released together into the cytoplasm
  • 95% belong to reserve pool and 5% stored in readily releasable pool
  • Thus small amount of insulin is released under maximum stimulatory conditions
insulin1
Insulin
  • Major stimulants
    • Glucose, amino acids, glucagon, GIP, CCK, sulfonylurea compounds, β-Sympathetic fibers
  • Major inhibitors
    • somatostatin, amylin, pancreastatin, α-sympathetic fibers
  • Stimulation of Beta cells results in exocytosis of the secretory granules
    • Equal amount of insulin and c peptide are released into circulation
    • Insulin circulates in free form and has half life of 4-8 minutes
    • Liver predominantly degrades insulin
    • C peptide is not readily degraded in the liver
    • Half life of c peptide averages 35 minutes
glucagon
Glucagon
  • Secreted by the alpha cells of the islets of Langerhans
  • Major stimulants
    • Amino acids, Cholinergic fibers, β-Sympathetic fibers
  • Major inhibitors
    • Glucose, insulin, somatostatin, α-sympathetic fibers
  • Main physiological role
    • increase blood glucose level through stimulation of glycogenolysis and gluconeogenesis
  • Antagonistic effect on insulin action
  • Release is inhibited by hyperglycemia and stimulated by hypoglycemia
somatostatin
Somatostatin
  • Secreted by the delta cells of the islets of Langerhans
  • Major Stimulants
    • High fat, protein rich , high carbohydrate meal
  • Generalized inhibitory effect
    • Inhibits the release of growth hormone
    • Inhibits the release of almost all peptide hormones
    • Inhibits gastric, pancreatic, and biliary secretion
  • Used to treat both endocrine and exocrine disorders
diseases and disorders
Diseases and Disorders
  • Acute Pancreatitis – Includes a broad spectrum of pancreatic disease
    • Varies from mild parenchymal edema to severe hemorrhagic pancreatitis associated with gangrene and necrosis
  • Chronic Pancreatitis
    • Is associated with alcohol abuse (most common), cystic fibrosis, congenital anomalies of pancreatic duct and trauma to the pancreas
  • Disruptions of the Pancreatic Duct
    • In adults, the most common cause is alcoholic pancreatitis
    • In children the most common cause is neoplasms. (tumors)
      • The fifth most common cause of cancer death
      • 90% of patients die within the first year after diagnosis
  • Adenocarcinoma of the Body and Tail of Pancreas
    • Represents up to 30% of all cases of pancreatic carcinoma
diseases and disorders1
Diseases and Disorders
  • Endocrine Tumors – Rare with an incidence of five per one million
    • Insulinoma: Most common endocrine tumor of the pancreas
  • Gastrinoma (Zollinger-Ellison Syndrome)
    • Identification of a islet cell tumor of the pancreas
    • Patient management is through control of gastric acid hypersecretion
  • Pancreatic Lymphoma
    • Involvement of pancreas with non-Hodgkin’s lymphoma is an unusual neoplasm
  • Pancreatic Trauma
    • Pancreas is injured in less than 2% of patients with abdominal trauma
diseases and disorders2
Diseases and Disorders
  • Diabetes Mellitus
    • Group of diseases characterized by high levels of blood glucose resulting from defects in insulin production, insulin action, or both
    • Leads to Hyperglycemia, or high blood glucose (sugar)
  • Estimated 20.8 million in US ( 7% of population)
  • Estimated 14.6 million diagnosed (only 2/3)
  • Consists of 3 types:

1) Type 1 diabetes

2) Type 2 diabetes

3) Gestational diabetes

http://faculty.smu.edu/jbuynak/images/Diabetes MellitusBuynak.ppt

diabetes mellitus
Diabetes Mellitus
  • Type 1 Diabetes (insulin-dependent diabetes)
    • cells that produce insulin are destroyed
    • results in insulin dependence
    • commonly detected before age 30
  • Type 2 Diabetes (non-insulin-dependent diabetes)
    • blood glucose levels rise due to

1) Lack of insulin production

2) Insufficient insulin action (resistant cells)

    • commonly detected after age 40
    • effects > 90% of persons with diabetes
    • eventually leads to beta cell failure (resulting in insulin dependence)
  • Gestational Diabetes
    • 3-5% of pregnant women in the US develop gestational diabetes

http://faculty.smu.edu/jbuynak/images/Diabetes MellitusBuynak.ppt

conclusions
Conclusions
  • Pancreas is a composite gland
    • Has exocrine and endocrine functions
  • Plays major role in digestion and glucose homeostasis