L4 - pancreas secretions

Question 1

function of pancreas

Answer 1

• exocrine - secretes pancreatic juice

- endocrine- secretes hormones of insulin and glycagon

Question 2

function of pancreatic juice

Answer 2

has enzyme rich secretion and alkaline secretion

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

Question 3

structure of the prancreas

Answer 3

acinar cells > acinus or secretory unit>lobule

Question 4

pathway of the pancreatic juice from the pncreas into the duodenum

Answer 4

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.

Question 5

types of pancreatic cell types

Answer 5

• acinar
• duct
• centroacinar
• goblet

Question 6

function of acinar cells

Answer 6

• produces and exports proteins like digestive enzymes

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

Question 7

function of duct cells

Answer 7

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

Question 8

function of centroacinar cells

Answer 8

located at the junctio of acinar and duct cells

-function not sure

Question 9

function of goblet cells

Answer 9

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

Question 10

how is acinar cell stimulated and what happens

Answer 10

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

Question 11

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

Answer 11

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

Question 12

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

Answer 12

• 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

-

Question 13

location of CFTR

Answer 13

on apical plasma membrane of pancreatic cells

Question 14

how is CFTR channels regulated

Answer 14

by secretin or increase in cAMP

-increasing the no of open channels

Question 15

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

Answer 15

• reduced HCO3- secretion and water by the ducts

- leads to malnutrition

Question 16

what is the rate of pancreatic secretion dependent on

Answer 16

• on the state whether you are fed or fasted

- the more fed you are, the rate increases

Question 17

role of CCK in pancreatic stimulation

Answer 17

• 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

Question 18

what molecule inhibits pancreatic secretions(PCS)

Answer 18

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

Question 19

phases in PCS

Answer 19

• celphalic
• gastric
• intestinal

Question 20

what happens in cephalic phase

Answer 20

• mediated by ACh in the vagus nerve

- secretes enzyme rich fluid with little HCO3

Question 21

what happens in gastric phase

Answer 21

• gastrin released from the G cells

- both types of secretion (enzymes and HCO3) increases

Question 22

what happens in intestinal phase

Answer 22

• 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

-

Question 23

how to prevent digestion in the pancreas

Answer 23

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

-

Question 24

two types of pancreatitis

Answer 24

acute and chronic

Question 25

causes of acute pancreatitis (AP)

Answer 25

-gallstones
ethanol
trauma 
steroids 
mumps 
hypercalcaemia

Question 26

diagnosis of AP

Answer 26

• abdominal pain
• serum amylase high
• CT scan

Question 27

what is chronic pancreatritis

Answer 27

inflammation of pancreas which doesnt heal

- cause - alcohol abuse