Exocrine Pancreas

Question 1

What is the main function of the exocrine pancreas?

Answer 1

Digestion

Question 2

Exocrine pancreas is similar to salivary glands. What is the functional anatomy of the exocrine pancreas made up from?

Answer 2

Acini - cavity in gland surrounded by secretory cells

Simple cuboidal epithelium

Question 3

Several excretory ducts (with cuboidal epithelium lining) combine to make what?

Answer 3

Accessory pancreas ducts

Question 4

What are the 2 main components of pancreatic juice?

Answer 4

HCO3-

Enzymes

Question 5

What is the function of HCO3- in pancreatic juice?

Answer 5

Neutralise stomach acid to protect small intestine mucosa

Create correct pH for digestive enzymes

Question 6

What are the functions of the enzymes in pancreatic juice?

Answer 6

Digest carbohydrates, proteins and fats for absorption in the small intestine

Question 7

Pancreatic juice has a similar ionic composition to what?

Answer 7

Blood

Question 8

Describe the ionic composition of pancreatic juice

Answer 8

HCO3- actively transported into duct lumen in exchange for Cl-
Water follows by osmosis
H+ transported into blood (negates alkaline tide)
HCO3- is reabsorbed into acinar cells (when normal flow rate). When high flow rate, not enough time to reabsorbed HCO3- so juice is highly alkaline
Constant Na+/K+

Question 9

Why are proteases secreted into the stomach in an inactive form?

Answer 9

To prevent auto digestion of the stomach

Question 10

What does amylase break down?

Answer 10

Starch to maltose

Question 11

What do lipases/phospholipases break down?

Answer 11

Fats to glycerol and fatty acids

Question 12

Pancreas juice contains what precursor for the enzyme trypsin?

Answer 12

Trypsinogen

Question 13

How is trypsinogen converted to trypsin?

Answer 13

By enteropeptidases on the duodenum epithelial surface

Question 14

What is the function of trypsin? Why do pancreatic cells produce a trypsin inhibitor?

Answer 14

Auto catalysis and activation of other proteases

To prevent auto digestion

Question 15

What are the three phases of digestion?

Answer 15

Cephalic phase
Gastric phase
Intestinal phase

Question 16

What is increased throughout all 3 phases of digestion?

Answer 16

Pancreatic juice secretion

Question 17

What is the cephalic phase mediated by?

Answer 17

Vagus

Question 18

What is the gastric phase mediated by?

Answer 18

Gastrin

Question 19

In carnivores, which phases of digestion are enzymatic?

Answer 19

Cephalic

Gastric

Question 20

In pigs/horses, which phases of digestion are enzymatic and ionic?

Answer 20

Cephalic

Gastric

Question 21

What is the intestinal phase mediated by?

Answer 21

Secretin / CCK

Question 22

What inhibits secretin?

Answer 22

Vasoactive inhibitory peptide (VIP)

Question 23

What is secretin? When is it released?

Answer 23

A hormone released from the duodenum

In response to H+

Question 24

What does secretin do?

Answer 24

Increase HCO3- secretion

Question 25

Secretin works by what feedback mechanism?

Answer 25

Negative | As acid chyme is neutralised, stimulus for secretin release decreases

Question 26

What is cholecystokinin? (CKK) When is it released?

Answer 26

A hormone release from the duodenum | Released in response to fat/protein metabolites

Question 27

What are fat/protein metabolites?

Answer 27

Components that make up fats/proteins e.g. fatty acids, glycerol, peptides

Question 28

What does cholecystokinin do?

Answer 28

Increase enzyme secretion | Cause the gall bladder to contract

Question 29

Cholecystokinin works by what feedback mechanism?

Answer 29

Positive feedback mechanism | Increased enzyme secretion. More fat/protein metabolites which stimulates more CCK release

Question 30

Physiological features of the exocrine pancreas change between species due to what?

Answer 30

Different eating patterns

Question 31

Describe the exocrine pancreas and juice secretion in ruminants

Answer 31

Constant secretion | due to constant flow of rumen contents into SI

Question 32

Describe the exocrine pancreas and juice secretion in carnivores?

Answer 32

Intermittent secretion | Due to intermittent flow of stomach contents to SI

Question 33

Describe the exocrine pancreas and juice secretion in horses

Answer 33

Continuous secretion as stomach contents flows continuously to SI However increases more after feeding to allow fermentation

Question 34

Pancreatic juice in horses is low in HCO3-. How are horses still able to neutralise stomach acid?

Answer 34

Copious secretion of HCO3- | HCO3- secretion by ileum