GI2 Flashcards Preview

PHYSIO II > GI2 > Flashcards

Flashcards in GI2 Deck (43):
1

what are the GI self-regulatory hormones?

-CCK
-secretin
-GIP
-gastrin
-motilin

2

what are the GI self-regulatory neurocrine secretions?

-Ach
-NO
-Substance P
-VIP
-Serotonin

3

what are the GI self-regulatory candidate hormones?

-enteroglucagon
-pancreatic polypeptide
-peptide YY

4

what are the GI self-regulatory paracrine secretions?

-histamine
-somatostatin
-serotonin

5

a gut hormone must:

-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

6

where is gastrin produced

G cells; duodenum and pancreas

7

what is gastrin's release stimulus?

peptides, AAs

8

what is gastrin's major action?

(+) parietal cell HCl secretion

9

where is secretin produced?

S cells in the duodenum; jejunum

10

what is secretin's release stimulus?

acid, fat, protein

11

what is secretin's major action?

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

12

where is CCK produced?

I cells; small intestine and enteric neurons

13

what is CCK's release stimulus?

fats, proteins

14

what is CCK's major action?

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

15

where is GIP produced?

K cells; duodenum and jejunum

16

what is GIP's release stimulus?

fats and glucose

17

what is GIP's major action?

(-) gastric secretions; (+) insulin secretion

18

where is motilin produced?

M cells; duodenum, jejunum

19

what is motilin's release stimulus?

increase in duodenal pH; ACh

20

what is motilin's major action?

antral and duodenal MMC, Phase III induction during digestion

21

what cells produce the greatest proportion of serotonin?

enterochromaffin cells
-present all throughout the GI tract

22

what does serotonin (5-HT) stimulate?

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

23

what stimulates enterochromaffin cells?

-hyperosmolality
-acidity

24

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

true

25

what are trophic effects of regulatory peptides?

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

26

what does gastric cause the growth of?

gastric mucosa

27

what two things cause the growth of intestinal mucosa?

-enteroglucagon
-cholecystokinin

28

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

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

29

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

-lower
-greater

30

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

-greater
-lower

31

what is a syncytium?

a multinucleated mass of protoplasm such as a striated muscle fiber

32

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

gap junctions

33

what are gap junctions?

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

34

how many connexons and connexins does each gap junction have?

2 connexons
12 connexins (6/connexon)

35

what is the basic electrical rhythm of GI smooth muscle?

slow waves

36

are slow waves always present?

yes

37

smooth muscle cells are ___ electrically and forma functional ___.

-coupled
-syncitium

38

what is electrical coupling between cells facilitated by?

gap junctions

39

are slow waves neurogenic or myogenic?

myogenic
-no neural input is required

40

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

ICC (interstitial cells of Cajal)

41

how do ICC cells work?

they partially depolarize and set basic electrical rhythm

42

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

yes

43

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

yes