11a. Pancreatic Function (Camtasia)

Question 1

What arteries supply the pancreas?

Answer 1

Celiac artery, superior mesenteric artery

Question 2

what structures are anterior to the pancreas?

Answer 2

stomach, colon, omentum, loops of small intestine

Question 3

what structures are posterior to the pancreas?

Answer 3

portal vein, IVC, aorta, superior mesenteric a and v, kidneys, vertebrae

Question 4

what structure passes through the head of the pancreas?

Answer 4

distal common bile duct

Question 5

why is the relationship of the distal common bile duct relative to the pancreas impt?

Answer 5

because if there is cancer in the head of the pancreas, it can lead to obstruction of the common bile duct –> jaundice

Question 6

the head of the pancreas lies alongside what structure?

Answer 6

lies within the curve of the duodenum

Question 7

what is the best imaging modality for visualizing the pancreas?

Answer 7

CT

Question 8

is pancreatic ischemia common? why?

Answer 8

no, dual blood supply

Question 9

venous drainage of the pancreas is thru what veins?

Answer 9

splenic v, superior mesenteric v

Question 10

how can diseases like pancreatitis and pancreatic cancer lead to problems with the spleen?

Answer 10

these dz states can involve the splenic vein, cause thrombosis, lead to vascular engorgement of the spleen. then venous shunt pathways between spleen and stomach, possible varices and hemorrhage.

Question 11

what does the exocrine portion of the pancreas do?

Answer 11

secretes digestive enzymes, water, and NaHCO3 into the duodenum

Question 12

embryologically, how does the pancreas initially appear?

Answer 12

2 components: ventral and dorsal pancreas

Question 13

with embryo development, what happens to form the adult pancreas?

Answer 13

ventral pancreas rotates with common bile duct. fuses to the dorsal pancreas. ducts also fuse to form the main pancreatic duct (called ventral pancreatic duct or Wirsungs duct).

Question 14

what happens in 10% of individuals that is a common variant of pancreatic duct anatomy?

Answer 14

Pancreas Divisum: dorsal and ventral ducts drain separately into duodenum

Question 15

pts with pancreas divisum are at incr risk for what?

Answer 15

higher risk for pancreatitis.

Question 16

two major functional units of the exocrine pancreas? what does each do?

Answer 16

• acinus: synthesize/store/secrete digestive pro-enzymes and enzymes, along with water and ions.
• ducts: secrete bicarb-rich pancreatic juice which neutralizes stomach acid

Question 17

acinar cells: arrangement? how do they stain?

Answer 17

arranged in spheres or tubules, around the central duct lumen.
stain red in the apical area due to acidic zymogen granules. stain blue in the basal area due to ER and nucleus

Question 18

regulation of exocrine secretion from the pancreas: what regulates secretion from the acini?

Answer 18

Endocrine substances: CCK and secretin.

Neurocrine substances: Ach, gastrin-releasing peptide (GRP), vasoactive intestinal polypeptide (VIP) and substance P

Question 19

regulation of exocrine secretion from the pancreas: what regulates secretion from the ducts?

Answer 19

Endocrine substances: secretin.

Neurocrine substances: Ach

Question 20

where are I cells located? what do they do? what stimulates them?

Answer 20

• in duodenum
• secrete CCK
• stimulated by meal nutrients (FAs, AAs)

Question 21

What does CCK do?

Ach? VIP? GRP?

Answer 21

• stimulates pancreatic enzyme secretion by both neural and hormonal pathways
• activates vagal afferent neurons, which leads to activation of vagal efferent neurons, which releases ACh, VIP, GRP.

ACh goes on to stimulate more pancreatic acinar + ductal secretions.

GRP stimulates pancreatic acinar secretions + G cells to secrete gastrin.

VIP stimulates gut motility via a variety of mechanism, including pancreatic secretions

Question 22

where are S cells located? what do they do? what stimulates them?

Answer 22

• duodenum and jejunum
• major sensor cell in duod that mediates pangreatic bicarb secretion. release secretin.
• stimulated by low pH

Question 23

what does secretin do?

Answer 23

enters circulation, causes pancreas to secrete bicarb

Question 24

at what pH do optimal digestion and absorption occur?

Answer 24

near neutral pH

Question 25

3 mechanisms that help the small intestine maintain pH near neutral?

Answer 25

• peptides and FAs from ingested food act as buffer
• duodenal mucosa absorbs H+
• pancreas, biliary system, duodenum secrete bicarb

Question 26

4 reasons why it is impt to maintain small intestine pH near neutral?

Answer 26

Main point: it is ideal for digestion and absorption

• inactivates pepsin
• incr FA and bile acid solubility
• prevents mucosal damage
• optimizes pH for brush border enzymes

Question 27

what are the most abundant form of pancreatic enzymes?

Answer 27

-proteases (90%)

also amylase, lipase, nucleases

Question 28

why are some enzymes stored in zymogen form in the pancreas?

Answer 28

because they would digest the panc otherwise

Question 29

why are amylase and lipase stored in the active form in the pancreas?

Answer 29

they don’t threaten to digest the pancreas: there is not much starch and fat there.

Question 30

where are the pancreatic zymogen enzymes converted to active form? what enzyme starts off the process of conversion?

Answer 30

• at the duodenal brush border, once they have been secreted

- enterokinase converts trypsinogen to trypsin, which starts the activation cascade

Question 31

what 6 things are present in the acinar cell zymogen granule that prevent the enzymatic activation cascade?

Answer 31

• enzymes synthesized as/present as inactive zymogens
• trypsin inhibitor is packaged in the granule
• enzymes enclosed in membrane-bound compartments
• enterokinase is present only in the small intestine
• the acidic pH within the zymogen granule inactivates trypsin
• tight ductal epithelium, resists diffusion of enzymes into panc stroma

Question 32

what other organ secretes amylase? what does amylase do?

Answer 32

salivary glands

amylase digest starch by cleaving alpha 1-4 glycosidic bonds