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Flashcards in GI3 Deck (46):
1

action potentials can occur when threshold potential is more ___ than (depolarized relative to) ~40mV.

positive`

2

what is the input for action potentials in the GI tract?

PS NS

3

what provides a low-resistance pathway for ions to move between smooth muscle cells?

gap junctions

4

in the absence of PS input:

-slow waves only
-no AP
-no contraction
-no change in muscle tension

5

PS input enables what:

-slow waves
-APs
-contraction
-increase in muscle tension

6

what do excitatory neurohormonal substances do?

-depolarize RMP, Vm
-increase likihood of contraction
-increase contraction/motility

7

what does sympathetic input do to the resting potential?

-hyperpolarizes it
-decreases contraction/motility

8

what cranial nerves are involved in prehension? sensory/motor

sensory: 1,2,5
motor: 5,7,9

9

mastication incorporates what into food?

salivary amylase

10

what are the two phases of swallowing?

-voluntary
-involuntary

11

what are the steps of swallowing?

-closure of pharynx
-glottis pulls under epiglottis
-closure of larynx

12

what kind of muscle is in the esophagus?

striated and smooth muscle

13

striated muscle of esophagus is under what kind of control?

somatic motor control by vagus

14

smooth muscle is under what kind of control?

ENS/ANS control

15

what plexus is present throughout the length of the esophagus?

myenteris plexus

16

both sphinters of the esophagus are normally (open/closed)

closed

17

what is the proximal part of the fundus?

fundus (storage region)

18

how does the fundus accomodate ingesta?

adaptive (receptive) relaxation

19

what is the distal part of the stomach?

antrum

20

what is the role of the antrum?

grind ingesta and present it to the SI

21

muscular activity of the antrum is increased by what?

PS (ACh) input

22

what hormones stimulate gastric motility?

-gastrin
-motilin

23

what hormones inhibit gastric motility?

-CCK
-secretin
-CIP

24

stomach emptying matches ___ and ___

-digestion and absorption

25

what are the 2 kinds of motility during the digestive phase of the SI?

-propulsive and non-proulsive

26

what are charactertics of propulsive motility in the SI

-aboral
-peristaltic
-slow waves
-travel slow distances

27

what are characteristics of non-propulsive motility in the SI?

-segmentation: results from localized contractions
-3-4 cm long
-mixing action

28

is there digestion in the inter-digestive phase in the GI tract?

yes

29

what does MMC stand for/do?

-migrating motility/myoelectric complex
-pushes undigested material out of SI

30

when is MMC most present?

between meals

31

___ _____ ultimately produces intense peristalsis and propulsive motility

-excitation-contraction coupling

32

what are the general functions of the colon?

-water and electrolyte absorption
-fermentation
-storage of feces

33

colonic motility facilitates ___ and thereby optimizes colonic functions.

mixing

34

what are two structural specializations of the colon?

-haustra (saccules)
-segmentation

35

what is colon mixing optimized by?

-haustra and segmentation

36

what is a strong mixing property of the colon?

retropulsion

37

what processes are influence by colonis motility?

-absorption
-fermentation

38

carnivores have a colonic pacemaker located near the juncture between ____ and ___ colon segements

transverse and descending

39

the horse has a colonic pacemaker located near the _____

pelvic flexure (ascending colon)

40

the internal smooth muscle anal sphincter is relaxed by what NS?

PS

41

the internal smooth muscle anal sphincter is relaxed by what NS?

sympathetic

42

the external striated muscle anal sphincter is (voluntary/involuntary)? and intervated by what?

-voluntary
-GSA pudendal nerve

43

what is the glandular stomach of the avian?

proventriculus

44

what is the muscular "gizzard" of the avian?

ventriculus

45

what happens in the crop?

mucous secretion/storage of fod

46

what happens in the paired ceca?

-urinary excretions
-reabsorption of water and electrolytes