General Surgery - GI Hormones & Physiology

Question 1

Define the products of the following cells:

Gastric parietal cells

Answer 1

HCl

Intrinsic Factor

Question 2

Product of Chief Cells?

Answer 2

Pepsinogen

PEPpy Chief

Question 3

Product of G Cells?

Answer 3

Gastrin

G cells are found in the antrum

G = Gastrin

Question 4

Mucous Neck Cell Products?

Answer 4

Bicarbonate mucus

Question 5

What is pepsin?

Answer 5

Proteolytic enzyme that hydrolyzes peptide bonds

Question 6

What is Intrinsic Factor?

Answer 6

Protein secreted by parietal cells that combines with vitamin B12 and enables absorption in the terminal ileum

Question 7

Name three receptors on the parietal cell that stimulates HCl release

Answer 7

Think HAG:

Histamine

Acetylcholine

Gastrin

Question 8

What is the enterohepatic circulation?

Answer 8

Circulation of bile acids from the liver to the gut and back to the liver via the portal vein

Question 9

Where are most of the bile acids absorbed?

Answer 9

Terminal Ileum

Question 10

How many times is the entire bile acid pool circulated during a typical meal?

Answer 10

Twice

Question 11

What are the stimulators of gallbladder emptying?

Answer 11

Cholecystokinin

vagal input

Question 12

What are the inhibitors of gallbladder emptying?

Answer 12

Somatostatin

sympathetics (it’s impossible to flee and digest food at the same time!)

vasoactive intestinal polypeptide (VIP)

Question 13

Source of cholecystokinin (CCK)?

Answer 13

duodenal mucosal cells

Question 14

what stimulates release of cck?

Answer 14

fat

protein

amino acids

HCl

Question 15

What inhibits release of CCK?

Answer 15

trypsin

chymotrypsin

Question 16

Actions of CCK?

Answer 16

Empties gallbladder

opens ampulla of Vater

slows gastric emptying

stimulates pancreatic acinar cell growth & release of exocrine products

Question 17

Source of secretin?

Answer 17

Duodenal cells

SPECIFICALLY: argyrophilic S cells

Question 18

Whats stimuates release of secretin?

Answer 18

pH <4.5 (acidity)

fat in the duodenum

Question 19

What inhibits release of secretin?

Answer 19

High pH in duodenum

Question 20

What are secretin actions?

Answer 20

Releases pancreatic bicarbonate, enzymes, H2O

Releases bile, bicarbonate

Decreases Lower Esophageal Sphincter (LES) tone

Decreases release of gastric acid

Question 21

Source of gastrin?

Answer 21

Gastric antrum G cells

Question 22

What stimulates release of gastrin?

Answer 22

stomach peptides/amino acids

vagal input

calcium

Question 23

What inhibits gastrin release?

Answer 23

pH <3.0

Somatostatin

Question 24

Actions of gastrin?

Answer 24

Release of HCl from parietal cells

Trophic effect on mucosa of the stomach and small intestine

Question 25

Source of somatostatin?

Answer 25

pancreatic D cells

Question 26

What stimulates somatostatin release?

Answer 26

FOOD

Question 27

Actions of somatostatin?

Answer 27

Globally inhibiting GI function

Question 28

Purpose of the colon?

Answer 28

Reabsorption of H2O, storage of stool

Question 29

Main small bowel nutritional source?

Answer 29

Glutamine

Question 30

What is the main nutritional source of the colon?

Answer 30

Butyrate (short chain fatty acid)

Question 31

Where is calcium absorbed?

Answer 31

Duodenum actively Jejunum passively

Question 32

Where is iron absorbed?

Answer 32

Duodenum

Question 33

Where is vitamin B12 absorbed?

Answer 33

Terminal ileum

Question 34

Which hormone primarily controls gallbladder contraction?

Answer 34

CCK

Question 35

What supplement does a patient need after removal of the terminal ileum or stomach?

Answer 35

Vitamin B12

Question 36

Main constituents of bile?

Answer 36

Water phospholipids (lecithins) bile acids cholesterol bilirubin

Question 37

What are most gallstones made of?

Answer 37

Cholesterol

Question 38

How do opiates affect the bowel?

Answer 38

By stimulating sodium absorption & inhibiting secretion in the ileum as well as decreasing GI motility by incoordinated peristalsis Therefore, place patients on stool softeners when dispensing pain medication

Question 39

Which type of muscle fibers, smooth or striated, does the esophagus contain?

Answer 39

BOTH upper third: striated muscle control of motor nerves middle third: mixed lower third: smooth muscle, primarily under control of vagal motor fibers

Question 40

Which electrolytes does the colon actively absorb?

Answer 40

Na+, Cl-

Question 41

Which electrolyte does the colon actively secrete?

Answer 41

HCO3- plays a role in diarrhea causing the patient to have a normal anion gap acidosis

Question 42

Which electrolyte does the colon passively secrete?

Answer 42

K+

Question 43

What is the gastrocolic reflex?

Answer 43

Increased secretory and motor functions of the stomach result in increased colonic motility

Question 44

What is the blood supply to the liver

Answer 44

75% from the portal vein, rich in products of digestion 25% from the hepatic artery, rich in O2 (but each provide for 50% of oxygen!)

Question 45

What are Peyer patches?

Answer 45

Nodules of lymphoid tissue with B & T lymphocytes in the small intestine that selectively sample lumenal antigens found in the terminal ileum