GI2

Question 1

what are the GI self-regulatory hormones?

Answer 1

• CCK
• secretin
• GIP
• gastrin
• motilin

Question 2

what are the GI self-regulatory neurocrine secretions?

Answer 2

• Ach
• NO
• Substance P
• VIP
• Serotonin

Question 3

what are the GI self-regulatory candidate hormones?

Answer 3

• enteroglucagon
• pancreatic polypeptide
• peptide YY

Question 4

what are the GI self-regulatory paracrine secretions?

Answer 4

• histamine
• somatostatin
• serotonin

Question 5

a gut hormone must:

Answer 5

• be excreted by a cell in the gut or exert its effect on the gut
• use endocrine route (blood)
• stimulated by food
• not dependent on neural control

Question 6

where is gastrin produced

Answer 6

G cells; duodenum and pancreas

Question 7

what is gastrin’s release stimulus?

Answer 7

peptides, AAs

Question 8

what is gastrin’s major action?

Answer 8

(+) parietal cell HCl secretion

Question 9

where is secretin produced?

Answer 9

S cells in the duodenum; jejunum

Question 10

what is secretin’s release stimulus?

Answer 10

acid, fat, protein

Question 11

what is secretin’s major action?

Answer 11

(+)HCO3- secretion, (-) HCl secretion

Question 12

where is CCK produced?

Answer 12

I cells; small intestine and enteric neurons

Question 13

what is CCK’s release stimulus?

Answer 13

fats, proteins

Question 14

what is CCK’s major action?

Answer 14

(+) pancreatic enzyme and insulin secretion; (+) bile secretion; satiety factor

Question 15

where is GIP produced?

Answer 15

K cells; duodenum and jejunum

Question 16

what is GIP’s release stimulus?

Answer 16

fats and glucose

Question 17

what is GIP’s major action?

Answer 17

(-) gastric secretions; (+) insulin secretion

Question 18

where is motilin produced?

Answer 18

M cells; duodenum, jejunum

Question 19

what is motilin’s release stimulus?

Answer 19

increase in duodenal pH; ACh

Question 20

what is motilin’s major action?

Answer 20

antral and duodenal MMC, Phase III induction during digestion

Question 21

what cells produce the greatest proportion of serotonin?

Answer 21

enterochromaffin cells

-present all throughout the GI tract

Question 22

what does serotonin (5-HT) stimulate?

Answer 22

• ENS
• vagal afferents (gut->brain)
• enterocyte secretion
• blood flow

Question 23

what stimulates enterochromaffin cells?

Answer 23

• hyperosmolality

- acidity

Question 24

T’F: stimulation of serotonin receptors can cause nausea?

Answer 24

true

Question 25

what are trophic effects of regulatory peptides?

Answer 25

- supply and demand - increase feed, increase demand - increase production and secretion of trophic factors

Question 26

what does gastric cause the growth of?

Answer 26

gastric mucosa

Question 27

what two things cause the growth of intestinal mucosa?

Answer 27

- enteroglucagon | - cholecystokinin

Question 28

what regulatory peptides are increased for cold adaptation? (increased food intake)

Answer 28

- CCK (elongation of intestinal villi) | - enteroglucagon (enhanced absorption)

Question 29

the greater the propulsive movement, the (higher/lower) the transit time and the (greater/lower) the transit rate.

Answer 29

- lower | - greater

Question 30

the lower the propulsive movement, the (higher/lower) the transit time and the (greater/lower) the transit rate.

Answer 30

- greater | - lower

Question 31

what is a syncytium?

Answer 31

a multinucleated mass of protoplasm such as a striated muscle fiber

Question 32

what faciliates protoplasmic continuity between smooth muscle cells, thereby inparting smooth muscles with the properties of a syncytium?

Answer 32

gap junctions

Question 33

what are gap junctions?

Answer 33

intercellular channels that permit exchange of substances(eg. Ca2+, cAMP, ATP) between cells)

Question 34

how many connexons and connexins does each gap junction have?

Answer 34

``` 2 connexons 12 connexins (6/connexon) ```

Question 35

what is the basic electrical rhythm of GI smooth muscle?

Answer 35

slow waves

Question 36

are slow waves always present?

Answer 36

yes

Question 37

smooth muscle cells are ___ electrically and forma functional ___.

Answer 37

- coupled | - syncitium

Question 38

what is electrical coupling between cells facilitated by?

Answer 38

gap junctions

Question 39

are slow waves neurogenic or myogenic?

Answer 39

myogenic | -no neural input is required

Question 40

what cells serve as the pacemaker cells of the GI tract?

Answer 40

ICC (interstitial cells of Cajal)

Question 41

how do ICC cells work?

Answer 41

they partially depolarize and set basic electrical rhythm

Question 42

do smooth muscle slow wave frequency, amplitude and kinetics differ between species?

Answer 42

yes

Question 43

do smooth muscle slow wave frequency, amplitude and kinetics differ between segments of the GI tract?

Answer 43

yes