Physiology Pancreatic and Biliary Functions Flashcards

1
Q

What is the total volume of bile and pancreatic secretions?

A

1 L bile
1 L pancreatic juice
Therefore total is 2L

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2
Q

What is the function of bile salts vs bile pigments?

A

Bile salts = fat digestion

Bile pigments = excreted

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3
Q

How much pancreatic (exocrine) secretions are produced per day?

A

1 L

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4
Q

Describe the pathway of how pancreatic secretions reach the duodenum.

A

Produced in acini (glands) –> ducts –> common bile duct –> sphincter of oddi –> duodenum

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5
Q

Name the two major components of exocrine pancreatic secretions.

A
Alkaline fluid - HCO3 (ducts)
Digestive enzymes (acinar glands)
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6
Q

Describe the alkaline fluid from the pancreas and its function.

A

Isosmotic with plasma
HCO3 rich - concentration increases with flow rate
Neutralizes acid chyme from stomach to optimize pH for pancreatic enzymes (6.7 - 9)

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7
Q

Which cells produce the isosmotic HCO3 rich solution?

A

Duct cells

Cl/HCO3 exchange - final composition variable

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8
Q

Name some examples of the digestive enzymes secreted by the pancreas.

A

Amylytic - pancreatic amylase
Nucleolytic - ribonuclease, deoxyribonuclease
Lipolytic - lipase, phospholipase
Proteolytic - trypsin, chymotrypsin, carboxypeptidase

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9
Q

What is produced in the acinar cells?

A

Inactive precursors of enzymes.

Released by exocytosis.

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10
Q

What activates trypsinogen to trypsin and what is the importance of this?

A

Enterokinase activates trypsinogen to trypsin.

This activates the other proenzymes

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11
Q

How are pancreatic secretions regulated?

A

Secretion increases during a meal - due to cephalic/gastric phases
Intestinal phase is dominant
Acid causes secretin to be released
Food causes CCK to be released.

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12
Q

What effect does increased duodenal activity (acid chyme from the stomach) have on the pancreas?

A

Causes secretin to be produced by duodenal cells (S cells)

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13
Q

What does secretin stimulate?

A

Production of HCO3 in ducts

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14
Q

What effect does the arrival of fatty acids, amino acids and sugars have on the pancreas?

A

Leads to production of cholecystokinin (CCK) by endocrine cells in duodenum (I cells)

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15
Q

What does CCK stimulate?

A

Acinar cell enzyme secretions

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16
Q

Describe the production of bile and its excretion.

A

Bile formed by hepatocytes lining the liver sinusoids

Excreted into bile canaliculi which modify its composition

17
Q

Describe the timing of the production of bile.

A

Produced continuously.

Concentrated and stored in gall bladder and ejected following a meal by contraction of the gall bladder.

18
Q

How much bile is secreted per day?

A

1L

19
Q

Describe the transport of bile into the duodenum.

A

Enters duodenum via bile duct/Sphincter of Oddi. (found at the major duodenal papilla)

20
Q

Describe the composition of the biliary secretions.

A

Bile pigments (bilirubin)
Cholesterol, phospholipids
Metabolites, excretory products (drugs)
HCO3 - neutralization of acid

21
Q

Describe what happens to bile salts.

A

They are synthesized and recycled via fat digestion/absorption.

22
Q

What does the enterohepatic circulation ensure?

A

Many substances secreted from the liver in bile are reabsorbed in the GIT and are not lost.

23
Q

Explain why gut bacteria facilitate recirculation of metabolites.

A

Often need to deconjugate metabolites to get reabsorption - this is often done by gut bacteria.
If taking antibiotics there may be less deconjugation meaning less reabsorption

24
Q

Explain the regulation of biliary secretions.

A

Bile salt recycling (enterohepatic)
Secretin - HCO3
CCK - contract gall bladder, relax Sphincter of Oddi

25
Q

What happens in CF?

A
CFTR defect
Reduced water/HCO3 secretion in pancreatic ducts 
Viscous mucus - plugs 
Restricts enzyme release
Malabsorption/damage
26
Q

What happens in chronic pancreatitis?

A
Due to alcohol 
Inflammation --> impaired secretion 
Malabsorption/steatorrhoea 
Inflammation --> damage/pain 
Endocrine effects also
27
Q

Explain what happens in gallstones.

A

Saturated solution precipitates stones (cholesterol)
Duct blockage –> pain (biliary colic)
Inflammation (cholecystitis)
Need a cholecystectomy/Lithotripsy (sounds/frequency that smashes stones)

28
Q

What can cause biliary obstructions?

A

Tumour, stone, inflammation (hepatitis)

29
Q

What is indicative of a biliary obstruction?

A

Bilirubin accumulates

Jaundice