Intro To GI Phys - Lopez

Question 1

What is the sphincter of Oddi important for?

Answer 1

Allowing passage of biliary substances

Question 2

What comprises the enteric (intrinsic) nervous system?

What is it derived from?

Answer 2

Submucosal and Myenteric plexus

Neural crest cells

Question 3

Where are PS cell bodies located?

What type of receptor?

Answer 3

Brainstem and sacral spinal cord

nAChR

Question 4

Where do sympathetic preganglionic efferent fibers arise from and where do they end?

Answer 4

In spinal cord and end in the prevertebral ganglia

Question 5

What is the 1 exception in the gut where the sympathetic system is not inhibitory?

Answer 5

Relaxation of sphincters

Question 6

What does the ENS contain?

Does it need CNS input?

Answer 6

Afferent and efferent neurons
INTERNEURONS

NO

Question 7

Describe the Vago-vagal reflex

What does it modulate?

Answer 7

Vagal efferents –> Nodose ganglion –> NTS –> Vagal efferents –> stomach

ENS responses

Question 8

What peptide uses paracrine signaling?

What other messenger also uses paracrine?

Answer 8

Somatostatin

Histamine

Question 9

What secretes somatostatin?

What is the stimulus?

Actions?

Answer 9

D cells of GI mucosa

Decreased luminal pH

Inhibit gastric H+ secretion, inhibit other GI hormones

Question 10

Where else is somatostatin secreted?

Answer 10

Hypothalamus

Delta cells of exocrine pancreas

Question 11

What secretes histamine?

What is its target?

Action?

Answer 11

ECL cells in stomach

Parietal cells

Stimulate acid production

Question 12

What defines specificity of hormones?

Answer 12

The receptors on the target cell

Question 13

What stimulates Gastrin secretion?

Answer 13

Small peptides, a.a.

Distention of the stomach, Vagal stimulation (GRP)

Question 14

What stimulates CCK secretion?

Answer 14

Small peptides, a.a.

Fatty acids

Question 15

What stimulates GIP secretion?

Answer 15

Oral glucose, a.a.

Fatty acids

Question 16

What stimulates Secretin secretion?

Answer 16

Fatty acids

H+ in the duodenum

Question 17

What makes CCK?

What makes Secretin

Answer 17

I cells in D, J

S cells in D, J

Question 18

What is Zollinger-Ellison syndrome?

Answer 18

Gastrin-secreting tumor in pancreas causing over production of gastric acid, resulting in duodenal ulcers

Question 19

What is steatorrhea?

Answer 19

Too much acid impairs pancreatic enzymes, cannot digest fat, therefore abnormal over-excretion of fat in feces due to lack of absorption

Question 20

What are the main actions of CCK?

Answer 20

INC pancreatic enzyme secretion
INC pancreatic bicarbonate secretion indirectly
Stimulates contraction of gallbladder and relaxation of Oddi
Stimulates growth of exocrine pancreas

Question 21

What does CCK inhibit?

Answer 21

Gastric emptying

Question 22

What are the main actions of secretin?

Answer 22

INC pancreatic bicarbonate secretion
INC biliary bicarbonate secretion
DEC gastric H+ secretion

Question 23

What does secretin inhibit?

Answer 23

Trophic effect of Gastrin

Question 24

GIP action?

Answer 24

INC insulin secretion from pancreatic B cells

DEC gastric H+ secretion

Question 25

Where is the feeding center located?

Answer 25

Lateral nucleus

Question 26

Where is the satiety center located?

Answer 26

Ventromedial nucleus

Question 27

Where does the integration signaling regulating food intake and energy expenditure happen?

Answer 27

Arcuate nucleus

Question 28

Describe the pathway that inhibits food intake and increases metabolism (anorexigenic)

Answer 28

Alpha-MSH released by POMC neurons | Alpha-MSH binds to MCR-4 in the 2nd order neurons

Question 29

Describe the pathway that increases feeding and storage of calories (orexigenic)

Answer 29

hunger stimulates release of NPY and AGRP NPY binds Y1R AGRP inhibits MCR-4

Question 30

What stimulates the POMC pathway and inhibits the NPY pathway?

Answer 30

Insulin, leptin, CCK

Question 31

What stimulates the NPY pathway?

Answer 31

Ghrelin

Question 32

What secretes Ghrelin?

Answer 32

Endocrine cells in the stomach

Question 33

Where does insulin bind? Action?

Answer 33

Receptors in satiety and hunger centers in hypothalamus INC metabolism DEC appetite

Question 34

what does CCK elicit? What does it Decrease? Increase?

Answer 34

Satiety DEC Ghrelin and gastric emptying INC gastric distention

Question 35

What secretes PYY? Where does it bind? Action?

Answer 35

L cells of ileum and colon post meal Y2 receptors of hypothalamus Inhibits NPY, releases inhibition of POMC neurons

Question 36

What secretes Leptin? Which pathway does it inhibit and stimulate? Action?

Answer 36

Adipose and endocrine cells in the stomach Inhibits NPY, stimulates POMC INC metabolism, DEC appetite and Ghrelin release

Question 37

Name all the sphincters in the gi tract

Answer 37

UES, LES, pyloris Sphincter of Oddi, Ileocecal valve Internal and external anal sphincter