Exam 6 General

Question 1

What factors are stimuli for BER?

Answer 1

• distention of duodenum
• nut content of chyme
• gastroenteric reflex (SI to stomach)
• hormones: CCK, gastrin, insulin, serotonin

Question 2

What hormones are inhibitors of BER?

Answer 2

• glucagon

- secretin

Question 3

Rate of chyme moving through SI

Answer 3

1 cm/min

Question 4

How far does a peristalsis contraction last?

Answer 4

3-5 cm

Question 5

What is the maximum concentration of bicarbonate the pancreas can secrete?

Answer 5

145 mEq/L (4x that of plasma concentration)

Question 6

What percentage of protein is digested by pepsin?

Answer 6

10-20%

Question 7

Pepsin is important for the digestion of what?

Answer 7

Collagen

Question 8

Trypsin, Chymotrypsin, carboxypolypeptidases, and elastase produce what?

Answer 8

Small peptides and amino acids

Question 9

Brush border peptidases produce what?

Answer 9

Amino acids

Question 10

What are the two emulsifiers of fat in the small intestine?

Answer 10

• bile salts

- lecithin (phospholipid)

Question 11

How is the rate of micelle formation determined?

Answer 11

Micelle formation and breakdown are in equilibrium

Question 12

What breaks down phospholipids?

Answer 12

Phospholipase A2

Question 13

How much Na+ is absorbed in the GI lumen?

Answer 13

95.5%

Question 14

What substances are actively absorbed in the SI?

Answer 14

• Ca2+
• (PO4)3-
• Mg2+
• Fe2+
• Bile Salts

Question 15

What triggers “Mass Movements” from the transverse to sigmoid colon 1-3 times per day for about 10 minutes?

Answer 15

Gastrocolic and Duodenocolic Reflexes

Question 16

Two unique and important functions of the colonic bacteria?

Answer 16

• Nutrient Salvage: undigested carbs to short chain fatty acids
• Vit K production

Question 17

What structures does CCK act on?

Answer 17

Gallbladder -> contract
Pancreas -> stim acinar cells
Stomach -> recept relax, decr epmtying, decr HCl secr
Sphincter of Oddi -> relax

all contribute to better digestion and absorption

Question 18

What pH level in the SI stimulates secretin release?

Answer 18

<4.5

Question 19

What pH levels stim max secretin release?

Answer 19

<3

Question 20

What is max bicarb output?

Answer 20

30 mEq/hr

Question 21

What phase of digestion does most secretin release occur?

Answer 21

Intestinal since it responds to low pH in SI

Question 22

What phase of digestion does most CCK release occur?

Answer 22

Intestinal since it responds to fatty acids and amino acids through CCK-RP as well as MP.

Question 23

What percentage of pancreatic secretion occurs in the cephalic phase? Gastric? What mechanism stimulates the secretion?

Answer 23

Cephalic: 20%
Gastric: 5-10%

Vago-Vagal Reflex does both

Question 24

What are the Na+ and K+ concentrations in pancreatic juice?

Answer 24

Always same as plasma

Question 25

HCO3- and Cl- conc in low flow panc secretions?

Answer 25

HCO3- low and Cl- high

Question 26

HCO3- and Cl- conc in high flow panc secretions?

Answer 26

HCO3- high and Cl- low

Question 27

Malnutrition with steatorrhea could be a sign of....

Answer 27

chronic pancreatitis: destruction of acinar cells means less panc juice (enzymes) secreted so less digestion and thus absorption.

Question 28

Without pancreatic enzymes how much fat is NOT absorbed?

Answer 28

60% 30-40% of carbs and prot not absorbed

Question 29

How much bile is produced by hepatocytes per day?

Answer 29

600-1000 ml/day

Question 30

What components of bile do hepatocytes secrete?

Answer 30

- bile salts (acids) - cholesterol - bilirubin - lecithin

Question 31

How does CCK stim bile secretion into the duodenum?

Answer 31

- contract the GB so more bile flows into common duct | - relax sphncter of oddi so more bile flows into duodenum

Question 32

What affect does secretin have on the liver?

Answer 32

Stimulates biliary ductal cells to secrete HCO3- (similar to pancreas)

Question 33

How are bile salts reabsorbed in the ileum?

Answer 33

-Apical sodium dependent bile salt transporter (ASBT)

Question 34

4 conditions that cause low ASBT activity

Answer 34

- Crohn's Disease - Congenital primary bile acid malabsorption - IBS - Idiopathic chronic diarrhea

Question 35

Other than hepatocyte dysfunction and blockages of the biliary ducts, what can cause a disorder of biliary secretion?

Answer 35

-intestinal mucosal defects impair bile salt reabsorption