GI 7

Question 1

What makes up the majority of pancreatic tissue - exocrine or endocrine?

Answer 1

exocrine (90%)

Question 2

2 Major Components of Pancreatic Secretion

Answer 2

1. Aqueous component
2. Enzymatic portion

Question 3

3 Functions of Aqueous Component of Pancreatic Secretion

Answer 3

high volume, high bicarbonate
1. flush pancreatic enzymes
2. prevent mucosal damag by acid and pepsin
3. bring pH up into neutral range

Question 4

Function of the Enzymatic Component of Pancreatic Secretion?

Answer 4

digest carbohydrates, lipids, and proteins

Question 5

zymogens

Answer 5

inactive form of enzymes in pancreas

Question 6

What proenzyme (zymogen) is most abundant?

Answer 6

trypsinogen (40%)

Question 7

What enzymes are secreted in active form?

Answer 7

amylase and some lipases

Question 8

What component of pancreatic secretion comes from acinar cells?

Answer 8

enzymatic component

Question 9

What component of pancreatic secretion comes from centroacinar and ductal cells?

Answer 9

aqueous component (incl. sodium, bicarbonate, and water)

Question 9

CFTR

Answer 9

cystic fibrosis transmembrane conductance regulator to allow outflow of Cl- ions into the lumen of the pancreatic duct

Question 10

2 Secondary Active Transporters in Pancreatic Ductal Cell

Answer 10

1. Bicarbonate into lumen
2. H+ into blood

Question 10

Is pancreatic venous blood acidic or alkaline?

Answer 10

acidic

Question 11

Which one is HCl secretion vs. Pancreatic?

Answer 11

Left = pancreatic secretion from ductal cell
Right = HCl secretion from gastric parietal cell

Question 12

Broad Generalism of Pancreatic Duct vs. Parietal Cells

Answer 12

Ion transport activities of pancreatic duct cells and similar, but directionally opposite, to those of the parietal cells.

Question 13

Major Factor in how much fluid and bicarbonate is secreted?

Answer 13

amount of acid in the duodenum

Question 14

Secretion of pancreatic enzymes is determined by what?

Answer 14

presence of digestive products from fat and protein in the duodenum

Question 15

What phase accounts for the most pancreatic secretion - cephalic, gastric, or intestinal?

Answer 15

intestinal (70-80%)

Question 16

Pancreatic Secretion: Cephalic Phase

Answer 16

stimulates enzymatic secretion; the gastric acid released from G cells signals the CNS then the vagus nerve will release ACh to act on acinar and/or duct cells (enzymes, water, bicarbonate release)

Question 17

Mediator of Pancreatic Secretion in the Cephalic Phase

Answer 17

acetylcholine (ACh)

Question 18

Pancreatic Secretion: Gastric Phase

Answer 18

distension of stomach, mediated by vagovagal reflexes

Question 19

S cells release ________

Answer 19

secretin (hormone)

Question 20

I cells release ________

Answer 20

CCK

Question 21

Gastric Acid and Fatty Acids trigger what in the intestinal phase of pancreatic secretion?

Answer 21

S cells release secretin, secretin acts on duct cell to release aqueous portion (bicarbonate)

Question 22

Fat and Protein trigger what in the intestinal phase of pancreatic secretion?

Answer 22

I cells release CCK, which either acts on neurons (stimulate ACh to act on cells) or hormonal (directly on acinar cells)

Question 23

Primary hormonal stimulus for acinar cells?

Answer 23

CCK

Question 24

Primary hormonal stimulus for centroacinar and duct cells?

Answer 24

secretin

Question 25

Two Disorders caused by Pancreatic Secretion

Answer 25

1. Cystic Fibrosis 2. Pancreatitis

Question 26

What is often one of the first signs of pancreatic dysfunction?

Answer 26

fat in the stool (enzymes responsible for fat digestion aren't activated)

Question 27

Cystic Fibrosis

Answer 27

failure of Cl- to leave the ductal cell, inhibits secretion of bicarbonate and water, pancreatic enzymes retained in the pancreas causing autodigestion, maldigestion and malabsorption d/t absence of enzymes in the intestine

Question 28

autodigestion

Answer 28

consequence of proenzymes/zymogens being activated before leaving the organ (usually after sitting for a long time), which begins to digest its own cells

Question 29

Pancreatitis

Answer 29

inflammation in the pancreas d/t autodigestion by pancreatic enzyme

Question 30

How is the pancreas protected from autodigestion under normal conditions?

Answer 30

zymogen, trypsin inhibitors

Question 31

Possible Causes of Pancreatitis

Answer 31

obstruction (gallstone, tumor), intracellular trpsin activation

Question 32

6 Constituents of Bile

Answer 32

1. Bile salts and phospholipids 2. Bile pigments 3. Cholesterol 4. Water 5. Inorganic Salts 6. Mucus

Question 33

Where do bile pigments come from?

Answer 33

breakdown of hemoglobin and cytochromes to give bile color

Question 34

Which constituent makes up the majority of bile?

Answer 34

water

Question 35

3 Components of the Biliary System

Answer 35

1. Liver 2. Bile Ducts 3. Gallbladder

Question 36

Is the liver an acinar gland?

Answer 36

yes

Question 37

Amphipathic

Answer 37

both polar and nonpolar molecules; important in fat absorption and digestion and antibacterial activity [in the case of bile salts]

Question 38

What % of bile salts are reabsorbed into intestinal capillaries from the ileum?

Answer 38

95%

Question 39

What % of bile salts are lost in feces?

Answer 39

5%

Question 40

How is bile secreted?

Answer 40

CCK and secretin released under stimulation from food in duodenum (from S and I cells), CCK contracts gallbladder, secretin enhances rich bicarbonate flow

Question 41

Sphincter of Oddi

Answer 41

at the end of the bile duct

Question 42

Is bile salt recycling a positive or negative feedback loop?

Answer 42

Postitive, via enterohepatic circulation - hepatocytes triggered to release more bile salts, keeps small intestine at more neutral pH

Question 43

What is the main component of gallstones?

Answer 43

cholesterol

Question 44

Effect of CCK on gallbladder

Answer 44

contracts gallbladder

Question 45

Effect of CCK on pancreas

Answer 45

binds to acinar cells - release aqueous portion

Question 46

Effect of CCK on stomach

Answer 46

inhibits gastric emptying

Question 47

Effect of CCK on sphincter of Oddi

Answer 47

relaxes the sphincter

Question 48

3 Functions of Secretin

Answer 48

1. Stmulates bicarbonate release 2. Inhibit gastric acid release 3. Inhibit gastrin release

Question 49

What is known as "nature's antacid?"

Answer 49

secretin