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PHYSIOLOGY III > L21: The Exocrine Pancreas > Flashcards

L21: The Exocrine Pancreas Flashcards

1
Q

the pancreas consists of what 2 types of glandular tissue

A
  • islets within parenchyma of glands (endocrine fxn)
  • exocrine glands (digestive enzymes)
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2
Q

pancreatic juice is rich in _____ and ______ and is secreted into the lumen of acini and modified on its way through the ducts

A

digestive enzymes and bicarbonate

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3
Q

pancreatic fluids drain where

A

into SI

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4
Q

what are the functions of pancreatic juice

A
  • neutralize acids from stomach when food enters duodenum pH changes dramatically
  • provide enzymes for the digestion of food (amylases, lipases, proteases)
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5
Q

what enzymes break down glucose polymers

A

amylases

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6
Q

what enzymes digest triglycerides, phospholipids and cholesterols

A

lipases

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7
Q

what enzymes break down proteins into amino acids, di/tri and oligopeptides

A

proteases

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8
Q

what is ecbolic secretion

A

protein secretion by acinar cells

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9
Q

what cells secrete the aqeous portion of pancreatic juice (electrolytes, bicarbonate, water)

A

centroacinar and ductal cells
= hydroelatic secretion

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10
Q

hydroelatic secretion

A

alkaline and watery secretion by duct cells

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11
Q

what is pancreatic bicarbonte secretion into the SI necessary for

A

neutralization of gastric acid emptied into SI

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12
Q

Bicarbonate is released via a chloride bicarbonate exchanger that is driven by…

A

the gradient for bicarbonate

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13
Q

the composition of pancreatic juice depends on ?

A

rate of secretion (flow rate)
at low flow - Cl- is main anion
at high flow, HCO3 concentration increases

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14
Q

elevated levels of _____ stimulate flow rate of pancreatic juice, causing a change in the composition of the fluid

A

secretin

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15
Q

what things regulate pancreatic secretion

A
  • CCK and gastrinstimulate acinar cells to secrete proenzymes
  • Secretin stimulates duct cells to secrete water and bicarbonate
  • vagal input stimulates acinar and duct cells
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16
Q

2 ____ and one _____ control mechanisms stimulate pancreatic secretion

A

hormonal
neural

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17
Q

vagal input (Ach) stimulates what cells

A

acinar and duct cells

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18
Q

CCK and gastrin stimulate what cells

A

acinar, to secrete proenzymes

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19
Q

secretin stimulates what cells

A

duct cells, to secrete water and bicarbonate

20
Q

pancreatic secretion occurs in what 3 phases

A
  • cephalic
  • gastric
  • intestinal
21
Q

what is the most important phase of pancreatic secretion and why

A

intestinal phase; it controls 80% of pancreatic secretion

22
Q

during the intestinal phase of pancreatic secretion, _____ is released from ___ cells in response to fats and amino acids in the duodenum

A

CCK, I-cells
CCK enters circulation and stimulates acinar cells

23
Q

during the intestinal phase of pancreatic secretion, _____ is released from ____cells in response to peptides and AA in stomach

A

gastrin

24
Q

during the intestinal phase of pancreatic secretion, in response to a low pH in the duodenum, ______ is released from ____ cells and stimulates duct cell secretion

A

secretin
S cells

25
Q

peptide hormone synthesized and relased by entero-endocrine I cells

A

CCK

25
Q

where are I cells present

A

dudoenum, jejunum, ileum

26
Q

what are the stimulators for I-cells (CCK) ; what do I cells target

A

released when fatty acids and amino acids enter duodenum
target: acinar cells

27
Q

what organs does CCK act on

A
  • gallbladder –> contractions
  • pancreas –> acinar secretion
  • stomach –> reduced emptying
  • sphincter of bile/pancreatic duct –> relaxation
28
Q

peptide hormone synthesized & released by entero-endocrine ‘S cells’

A

secretin

29
Q

where can S cells be found

A

duodenum

30
Q

what is the stimulator for S cells and what do S cells target

A

low pH (<4.5) in the duodenum
target: Duct cells

31
Q

what phases of pancreatic secretion share regulation by the vagal pathway

A

cephalic and gastric

32
Q

pancreatitis occurs when…

A

digestive enzymes are activated upon release into the pancreatic duct system which causes autophagy and inflammation

33
Q

an inflammation of the pancreas with histological presence of edema, neutrophilic infiltrate and necrosis

A

pancreatitis

34
Q

what can cause pancreatitis

A
  • obstruction causing impaired flow in pancreatic ducts - zymogen granules and proenzymes get trapped in ducts and prematurally activate
  • spontaneous trypsinogen cleavage overwhelming the trypsin inhibitor causing premature activation of trypsin
35
Q

why does pancreatitis cause malabsorption and maldigestion causing anorexia, lethargy, exercise intolerance/weakness, V/D+, abdominal pain, dehydration, fever, arrythmia (caused by electrolyte imbalance)

A

due to a lack of enzymatic activity

36
Q

what is the key factor in initiating pancreatic inflammation

A

activation of trypsin within the acinar cells

37
Q

pancreatic lipases ______ lipids (triglycerides) which are used for long term energy storage

A

hydrolyze

38
Q

triglycerides are apolar and have to be converted into _____ in order to be transported

A

glycerol, monoglycerides, diglycerides, fatty acids

39
Q

what cells produce pancratic lipases

A

pancreatic acinar cells

40
Q

what proteins maintain the bicarbonate gradient

A
  • Na HCO3 cotransporter
  • intracellular carboanhydrase (CA)
  • Na-K ATPase
  • Na-H exchanger
  • proton pump
  • chloride channel + exchanger
41
Q

digestive enzymes are activated and work best in an ______ environment

A

alkaline

42
Q

what are the 4 types of pancreatic digestive enzymes

A

proteases
amylolytic enzyme
lipases
nucleases

43
Q

where are digestive enzymes activated

A

in the intestinal lumen of the duodenum

44
Q

what enzyme converts inactive trypsinogen into active trypsin which is then able to activate other proenzymes

A

enterokinase

45
Q

what is the function of protease inhibitors in the zymogen granule

A

blocks the action of prematurely activated enzymes

46
Q

what is the function of nondigestive proteases

A

they degrade active enzymes

PHYSIOLOGY III (31 decks)

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