Exocrine Pancreas

Question 1

Anatomically, how is the pancreas situated?

Answer 1

Retroperitoneal (apart from tail)

Question 2

Which organ is the tail of the pancreas attached to?

Answer 2

Spleen

Question 3

Which part of the pancreas is derived from the ventral bud?

Answer 3

Uncinate process

Question 4

Which part of the pancreas is derived from the dorsal bud?

Answer 4

All of the pancreas apart from the uncinate process

Question 5

Describe the blood supply to the pancreas.

Answer 5

Main blood supply = coeliac trunk (direct branch of aorta).

Head of pancreas = superior mesenteric artery

Question 6

Describe the venous drainage of the pancreas.

Answer 6

Splenic vein

Question 7

Name the 2 substances that the exocrine pancreas secretes.

Answer 7

HCO3-

Digestive enzymes

Question 8

Which tissue of the pancreas secretes exocrine substances?

Answer 8

Acinar tissue

Question 9

Which specific cells secrete HCO3?

Answer 9

Duct cells = Epithelial cells lining the duct

Question 10

Why is HCO3 secreted?

Answer 10

In order to protect the duodenal mucosa from gastric acid.

Question 11

Which hormone stimulates the release of HCO3?

Answer 11

Secretin

Question 12

Where is HCO3 secreted into?

Answer 12

The pancreatic duct lumen

Question 13

Describe how HCO3- is secreted.

Answer 13

1. H+ is pumped out of the duct cell in exchange for Na+
2. H+ reacts with HCO3- in the blood to form carbonic acid which dissociates into H20 and CO2
3. CO2 diffuses into the duct. Carbonic anhydrase reacts H2O with the CO2 to form carbonic acid. This time it dissociates into H+ and HCO3-
4. The H+ is then pumped out again and the whole cycle starts again

Question 14

Which specific cells secrete digestive enzymes?

Answer 14

Gland cells

Question 15

Which hormone stimulates the release of digestive enzymes?

Answer 15

CCK - in response to proteins and triglycerides in the small intestine

Question 16

Name two active digestive enzymes and their roles.

Answer 16

Alpha amylase: Converts starch to maltose

Lipase: Converts triglycerides to fatty acids

Question 17

Name a precursor digestive enzyme.

Answer 17

Trypsinogen. Enterokinase splits off a peptide from trypsinogen to form the active enzyme trypsin. Trypsin then goes on to break down proteins.

Question 18

Name the hormone that inhibits pancreatic exocrine secretion.

Answer 18

Somatostatin, produced by D cells in the islets of Langerhans

Question 19

Describe pancreatic secretion in the cephalic and gastric phases of digestion.

Answer 19

Parasympathetic stimulation from vagus nerve causes acinar cells to produce digestive enzymes. In response to sensory info on eating and seeing food.