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30 Cards in this Set
- Front
- Back
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What is the pancreas?
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•Fresh: White with pink tinge
•Bumpy surface •Appears lobulated •Head, Body, and Tail •Main Pancreatic Duct enters the Duodenum •Arises as a diverticulum off of primitive gut •Exocrine and Endocrine functions –Different cells |
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What are the two types of cells that make up the pancreas?
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•Stroma: Capsule
–Peritoneal Mesothelium –Lobulation •Parenchyma –Exocrine •Acini –Endocrine •Pancreatic Islets of Langerhans |
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What is the structure of the exocrine pancreas?
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•Secretory Units
–Organized as Acini –Each acinus contains about 50 secretory cells –Each lobule contains hundreds of acini •Principal secretory cells are pyramidal with typical protein-secreting morphology –Apical surfaces do not come together completely –Pale-staining cell in center: Centroacinar Cell •Unique to pancreas |
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What does this image show?
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Pancreatic Acinus
Note the centroacinar cells |
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What does this image show?
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Acini and centroacinar cells.
Note the pale nuclei in the middle of acinar--> centroacinar cells |
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What does this image show?
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Pancreatic Acinar Cells
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What are the cell types that make up the duct system of the pancreas?
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•Intercalated Duct
–Simple squamous •Intralobular Duct –Simple cuboidal or low columnar •Interlobular Duct –Simple cuboidal or low columnar •Main Pancreatic Duct (Duct of Wirsung) –Simple columnar with occasional Goblet Cells |
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What is the function of the exocrine pancreas?
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•Synthesizes and secrete Pancreatic Juice
–1500 ml/day –More than 15 digestive enzymes secreted by acinar cells •Many secreted in inactive form (Zymogens) –Bicarbonate buffer secreted by intercalated duct cells •5× more concentrated than plasma •Decreases acidity of Chyme |
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How is the exocrine function of the pancreas controlled?
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•Secretion is continuous but affected by hormonal and neural influences
–Hormonal •Secretin: S cells in duodenum –Bicarbonate-buffered watery solution –Enhances action of CCK •Cholecystokinin: I cells in duodenum –Enzyme-rich solution –Enhances action of secretin –Neural •Parasympathetic functions like CCK •Sympathetic inhibits secretion of buffer and enzymes |
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What cells make up the endocrine pancreas?
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•Pancreatic Islets (of Langerhans)
–2% of total mass –0.5–2.0 × 106 islets –Few to several hundred cells –Cords of cells surrounded by fenestrated capillaries |
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What are the islet cell types?
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•Each secretes only a single hormone
•Alpha or A Cells: 20% of total –Glucagon •Beta or B Cells: 60–80% of total –Insulin •Delta or D Cells: ≈5% of total –Somatostatin •F Cells or PP Cells: Rare –Pancreatic Polypeptide |
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What hormones are secreted and or affect the pancreas?
What do they do? |
•Glucagon: 29 amino acids
–Raises blood sugar by stimulating breakdown and release of glycogen –General regulator of protein metabolism •Insulin: 51 amino acids; 2 peptide chains –Reduces blood sugar by stimulating cellular uptake –Induces conversion of glucose into glycogen •Somatostatin: 14 amino acids –Secreted by many tissues •Many functions, including inhibitor of Somatotropin –In pancreas, inhibits release of glucagon, insulin, and other exocrine secretions –Reduces GI tract motility and gallbladder contraction •Pancreatic Polypeptide: 36 amino acids –Reduces secretion of bicarbonate buffer and of bile (relaxes muscle layer of gallbladder) –Opposes action of CCK |
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What controls endocrine secretion of the pancreas?
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•Blood Sugar
–Controls release of glucagon and insulin •Increased [Glucose] and [Fatty Acid] in duodenum stimulates K Cells to release Gastric Inhibitory Peptide (GIP) –GIP acts on B cells to release insulin –GIP acts on Parietal Cells to inhibit release of HCl |
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How do sympathetic and parasympathetic neurons affect the release of insulin and glucagon?
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•Islets innervated by both Sympathetic and Parasympathetic neurons
Insulin Glucagon Sympathetic ─ + Parasympathetic + ─ |
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What is saliva?
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•Saliva is general name applied to various secretions from salivary glands
–1.0–1.5 liters/day in human –Up to 60 liters/day in cow! •Both major and minor salivary glands –Minor: Constitutive secretion •No capsule •No fat •Named according to location |
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What are the 3 major salivary glands?
What do they all have in common? |
•3 major salivary glands
–Parotid –Submandibular (Submaxillary) –Sublingual –All are paired –All located outside of oral cavity •Have large ducts –All are encapsulated |
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What does the stroma and parenchyma of the salivary glands look like?
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•Stroma
–Dense, collagenous, connective tissue capsule –Strands of tissue extend into gland to subdivide into lobes and lobules •Parenchyma –Functional units are called Salivons •Includes acinus of secretory cells and ducts cells that modify primary secretory product •Pyramidal secretory cells arranged a lumen and surrounded by Myoepithelial Cells |
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What does this image show?
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Salivary Gland Structure
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What is the acinar structure of the pancreas?
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•2 Types
–Serous •Typical morphology of protein-secreting cell •Primary products are Amylase (Ptyalin) and Lysozyme –Mucous •Pale in H&E preps •Apical cytoplasm filled with mucinogen granules •Frothy appearance •Nuclei often pressed flat against basal wall •May have crescent-shaped Serous Demilunes |
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What functions does the salivary gland duct provide?
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•Duct system provides two functions
–Transport of secretions to oral cavity –Modification of the secretory product •Saliva is hypotonic •Higher [K+] and lower [Na+] than plasma •Active Na+/K+ pump in certain duct cells •Saliva is buffered with bicarbonate |
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What are the ducts of the salivary glans?
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•Intercalated Duct
–Initial segment –No Centroacinar Cells –Simple squamous to low cuboidal –Surrounded by myoepithelial cells •Striated Duct –Simple columnar cells –Very eosinophilic –Centrally or apically located nuclei –Extensive basal infoldings of the membrane •Interlobular Duct –Larger ducts in the connective tissue separating lobules –Simple columnar or pseudostratified columnar –Occasional goblet cells •Excretory Ducts –Largest ducts that take product out of the gland |
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What are the properties of the parotid gland?
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•Purely serous
•Largest salivary gland •May have significant amount of adipose tissue –Serous secretory cells: 90% –Mucous secretory cells: 0% –Striated duct cells: 5% –Other cells: 5% |
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What does this image show?
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Parotid Gland
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What are the properties of the submandibular gland?
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•Mixed, Seromucous gland
•Mainly serous acini •Most mucous acini have serous demilunes •Very little fat in the gland –Serous secretory cells: 80% –Mucous secretory cells: 5% –Striated duct cells: 5% –Other cells: 10% |
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What does this image show?
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Submandibular Gland
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What does this image show?
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Submandibular Gland
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What are the properties of sublingual gland?
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•Mixed Mucoserous gland
•Mucous acini predominate –Usually capped with serous demilunes •Capsule less prominent that other glands –Serous secretory cells: 30% –Mucous secretory cells: 60% –Striated duct cells: 3% –Other cells: 7% |
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What does this image show?
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Sublingual Gland
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What are the functions of saliva?
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•Digestion
–Amylase –Taste perception •Maintenance of the Teeth –Antimicrobial functions retard tooth decay –Calcium and phosphorus instrumental in posteruptive mineralization of the teeth •Articulation –Saliva moistens oral cavity, easing movement of tongue and other structures required for proper speech •Protection –Contains antimicrobials –Buffers oral cavity –Washes away debris –Promotes rapid wound healing |
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How is saliva secretion controlled?
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•Glands richly supplied with blood vessels and nerves
•Both parasympathetic and sympathetic nerves are stimulatory –Parasympathetic stimulation leads to secretion of watery, organic-poor fluid –Sympathetic stimulation leads to secretion of thicker, more viscous saliva rich in organics |
