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66 Cards in this Set
- Front
- Back
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How much does the pancreas weigh?
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Between 100-150 g
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Where is the head of the pancreas nestled?
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Within the arms of the c-shaped duodenum
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What runs the length of the pancreas?
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The pancreatic duct
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What is the pancreas septated into? By what?
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Into lobules by loose collagenous tissue septations.
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2 types of pancreatic functions:
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-Exocrine
-Endocrine |
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What does the exocrine pancreas secrete?
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A cocktail of pancreatic enzymes
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What secretes the enzymes?
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Acini
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What are the ducts that the Acini secretes into? (4 in the system)
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1. Intercalated
2. Intralobular 3. Interlobular 4. Pancreatic |
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What does the pancreatic duct lead into?
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The duodenum
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What does the endocrine pancreas consist of?
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Islets of Langerhans
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Where are islets of langerhans?
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Distributed randomly throughout acini and ducts.
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What does the endocrine pancreas secrete?
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Hormones that control carbohydrate metabolism
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What induces the exocrine pancreas to secrete its juices?
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Hormones released from the duodenum in presence of food:
-Secretin -CCK |
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What is pancreatic juice composed of?
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-Alkaline fluid
-Enzymes and zymogens |
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How/where are digestive enzymes stored prior to being released?
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As zymogen granules in the cytoplasm of acinar cells.
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Why are the digestive enzymes stored as granules?
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So they can be released rapidly after a meal.
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Why are they stored as proenzymes?
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So they don't autodigest the pancreatic tissues.
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What is the functional unit o the exocrine pancreas?
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The acinus
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What induces acinar cells to secrete enzymes into the lumen in the form of zymogen granules?
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CCK
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What stimulates centroacinar cells to secrete alkaline fluid into the pancreatic juice?
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Secretin
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2 functions of the bicarbonate fluid secreted by centroacinar cells:
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1. Solubilization of zymogen granules
2. Neutralization of duodenal acidic chyme |
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What is the shape of acinar cells?
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Pyramidal
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Where is the nucleus located in acinar cells?
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Basally
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What prominent organells are in the basal cytoplasm of acinar cells?
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RER
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Where are proenzymes modified and packaged into zymogen granules?
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In the golgi
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How are zymogen granules released from acinar cells?
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Via exocytosis at the apical lumen surface.
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How do new zymogen granules compare to old?
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They appear less electron dense and are less numerous.
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How is pancreatic juice transported to the duodenum?
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Via a network of pancreatic ducts.
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What is part 1 of the duct system?
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Juice released from centroacinar cells is released into the INTERCALATED DUCTS.
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What do intercalated ducts flow into?
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Intralobular ducts
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What do intralobular ducts flow into?
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Interlobular ducts
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What do intralobular ducts flow into?
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The main pancreatic duct
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Where are proenzymes activated?
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In the intestine itself - the duodenum.
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What is the first enzyme in the cascade that activates proenzymes?
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Enterokinase
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Where is enterokinase made and secreted?
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From the intestinal surface epithelial cells, in their brush border.
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What enzyme is activated by enterokinase?
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Trypsinogen -> trypsin
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What does trypsin do?
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Proteolytically cleaves other proenzymes.
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What is the most common ailment associated with the pancreas?
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Pancreatitis
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What causes pancreatitis?
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Inflammation of the pancreas caused by necrosis of acinar cells.
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Where are the pancreatic endocrine cells?
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Clustered in Islets of Langerhans
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Where is the higher concentration of Islets of Langerhans cells?
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In the tail
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2 major hormones produced by the endocrine pancreas:
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-Insulin
-Glucagon |
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Stimulus for insulin secretion:
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high serum glucose levels
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stimulus for glucagon secretion:
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low serum glucose levels
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What tissues are acted on by insulin?
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Peripheral tissues:
-Liver -Skeletal muscle -Adipose tissue |
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4 cell processes stimulated by insulin:
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1. Uptake of glucose
2. Phosphorylation of glucose 3. Use of glucose 4. Making glycogen in liver |
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2 results of insulin secretion dysfunction:
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-Diabetes mellitus
-Hyperglycemia |
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What does Glucagon act on?
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Hepatocytes
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Result of glucogan's effect:
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Gluconeogenesis and Glycogenolysis
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4 principle cell types within islets of langerhans:
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-a-cells
-B-cells -d cells -pp cells |
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What do alpha cells secrete? What percent of all islet cells?
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Secrete glucagon
15-20% |
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What do beta cells secrete? What percent of all islet cells?
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Secrete insulin
70% |
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What do delta cells secrete? What percent of all islet cells?
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Somatostatin
5% |
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What do pp cells secrete? What percent of all islet cells?
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Pancreatic polypeptide
1% |
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What happens to islet cells when glucose levels are high in serum?
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Glucose transports into beta cells via Glut-2
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What is glucose used for?
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Making ATP
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What happens in Beta cells when ATP is high?
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It closes ATP-sensitive POTASSIUM channels
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What happens when K channels close?
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Membrane potential changes and opens voltage-gated Ca channels
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When calcium levels increase in beta cells what results?
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Prestored insulin vesicles dock with the plasma membrane and Insulin is spilled into blood.
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What is the family of diseases that results from glucose imbalance in the serum?
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Diabetes mellitus
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2 subtypes of diabetes mellitus:
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-Insulin dependent type I
-Insulin independent type II |
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What is the main feature of Type I diabetes?
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Autoimmune destruction of Beta cells
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Who gets Type I diabetes?
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Children / young adults
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What is the most common form of diabetes?
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Type II
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What characterises Type II diabetes?
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Insulin resistance - they make it but don't respond to it.
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2 future cures for diabetes type I:
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-Islet cell transplantation
-Microencapsulation of islets |
