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66 Cards in this Set

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