L4 - pancreas secretions Flashcards

1
Q

function of pancreas

A
  • exocrine - secretes pancreatic juice

- endocrine- secretes hormones of insulin and glycagon

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2
Q

function of pancreatic juice

A

has enzyme rich secretion and alkaline secretion

  • enzymes used for digestion
  • alkaline secretion neutralising the pH and for protection of intestinal mucosa
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3
Q

structure of the prancreas

A

acinar cells > acinus or secretory unit>lobule

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4
Q

pathway of the pancreatic juice from the pncreas into the duodenum

A

from acinar cells > intercalculated ducts > intralobular duct > interlobular ducts > main pancreatic ducts

  • the pancreatic ducts merge with the common bile duct
  • both juice and bile’s flow is controlled by the sphincter of Odii.
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5
Q

types of pancreatic cell types

A
  • acinar
  • duct
  • centroacinar
  • goblet
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6
Q

function of acinar cells

A
  • produces and exports proteins like digestive enzymes

- stimulated CCK rececptors and ACH receptors leads to increased enzyme secretion

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7
Q

function of duct cells

A

transports electrolytes and secretes HCO3 rich fluid for alkalinisation and hydration of the proteins secretions produced by the acinar cells

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8
Q

function of centroacinar cells

A

located at the junctio of acinar and duct cells

-function not sure

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9
Q

function of goblet cells

A

-produces mucus for lubrication, hydration, mechanical protection of epithelial cells

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10
Q

how is acinar cell stimulated and what happens

A
  1. ACh and CCK activate PKC (protein kinase ) and leads to Ca2+ influx. This leads to vesicles containing enzymes being released by exocytosis
  2. VIP and secretin activate adenylyl cyclas which produces cAMP and activates PKA
  • also stimulates gallbladder to release bile into the duodenum
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11
Q

mechanism of secreting HCO3 rich fluid from the Centro acinar and duct cells

A
  1. CO2 diffuses into the cells and react with water to make CA
  2. CA dissociates into HCO3 and H ions
  3. HCO 3 transported out by Hco3- cl exchanger and the H ions are secreted into the blood
  4. the H ions helps to neutralise the alkaline tide in the blood caused by the stomach as it secretes acid
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12
Q

what anion channel does the mechanism of HCO3 rich fluid depend on

A
  • Cl- ions
  • the ions are transported out of the cell into the lumen of the pancreas through CFTR (regulated by cAMP
  • this allows the CL- ions to be transported back into the cells for exchange of HCO3 ions

-

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13
Q

location of CFTR

A

on apical plasma membrane of pancreatic cells

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14
Q

how is CFTR channels regulated

A

by secretin or increase in cAMP

-increasing the no of open channels

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15
Q

how does a defect in CFTR leads to symptoms of cystic fibrosis

A
  • reduced HCO3- secretion and water by the ducts

- leads to malnutrition

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16
Q

what is the rate of pancreatic secretion dependent on

A
  • on the state whether you are fed or fasted

- the more fed you are, the rate increases

17
Q

role of CCK in pancreatic stimulation

A
  • stimulates proteins secretion
  • regulated by LCRF (luminal CCK releasing factor) so in a fasting state, the factor is degraded by the digestive enzymes so no CCK is stimulated
18
Q

what molecule inhibits pancreatic secretions(PCS)

A
  • somatostatin in the d cells in the pancreas
    -inhibits exo and endo secretions, CCK, secretin
    -
19
Q

phases in PCS

A
  • celphalic
  • gastric
  • intestinal
20
Q

what happens in cephalic phase

A
  • mediated by ACh in the vagus nerve

- secretes enzyme rich fluid with little HCO3

21
Q

what happens in gastric phase

A
  • gastrin released from the G cells

- both types of secretion (enzymes and HCO3) increases

22
Q

what happens in intestinal phase

A
  • acid stimulates S cells in the duodunum > secretin released> stimulates > duct cells to release HCO3 fluid
  • lipids stimulates release of CCK so digestive enzymes are released

-

23
Q

how to prevent digestion in the pancreas

A
  • digestive enzymes exist as inactive zymogens
  • they become activated once they get in contact with enterokinase in the brush border of the duodenum

-

24
Q

two types of pancreatitis

A

acute and chronic

25
Q

causes of acute pancreatitis (AP)

A
-gallstones
ethanol
trauma 
steroids 
mumps 
hypercalcaemia
26
Q

diagnosis of AP

A
  • abdominal pain
  • serum amylase high
  • CT scan
27
Q

what is chronic pancreatritis

A

inflammation of pancreas which doesnt heal

- cause - alcohol abuse