GI3

Question 1

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

Answer 1

positive`

Question 2

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

Answer 2

PS NS

Question 3

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

Answer 3

gap junctions

Question 4

in the absence of PS input:

Answer 4

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

Question 5

PS input enables what:

Answer 5

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

Question 6

what do excitatory neurohormonal substances do?

Answer 6

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

Question 7

what does sympathetic input do to the resting potential?

Answer 7

• hyperpolarizes it

- decreases contraction/motility

Question 8

what cranial nerves are involved in prehension? sensory/motor

Answer 8

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

Question 9

mastication incorporates what into food?

Answer 9

salivary amylase

Question 10

what are the two phases of swallowing?

Answer 10

• voluntary

- involuntary

Question 11

what are the steps of swallowing?

Answer 11

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

Question 12

what kind of muscle is in the esophagus?

Answer 12

striated and smooth muscle

Question 13

striated muscle of esophagus is under what kind of control?

Answer 13

somatic motor control by vagus

Question 14

smooth muscle is under what kind of control?

Answer 14

ENS/ANS control

Question 15

what plexus is present throughout the length of the esophagus?

Answer 15

myenteris plexus

Question 16

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

Answer 16

closed

Question 17

what is the proximal part of the fundus?

Answer 17

fundus (storage region)

Question 18

how does the fundus accomodate ingesta?

Answer 18

adaptive (receptive) relaxation

Question 19

what is the distal part of the stomach?

Answer 19

antrum

Question 20

what is the role of the antrum?

Answer 20

grind ingesta and present it to the SI

Question 21

muscular activity of the antrum is increased by what?

Answer 21

PS (ACh) input

Question 22

what hormones stimulate gastric motility?

Answer 22

• gastrin

- motilin

Question 23

what hormones inhibit gastric motility?

Answer 23

• CCK
• secretin
• CIP

Question 24

stomach emptying matches ___ and ___

Answer 24

-digestion and absorption

Question 25

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

Answer 25

-propulsive and non-proulsive

Question 26

what are charactertics of propulsive motility in the SI

Answer 26

- aboral - peristaltic - slow waves - travel slow distances

Question 27

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

Answer 27

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

Question 28

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

Answer 28

yes

Question 29

what does MMC stand for/do?

Answer 29

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

Question 30

when is MMC most present?

Answer 30

between meals

Question 31

___ _____ ultimately produces intense peristalsis and propulsive motility

Answer 31

-excitation-contraction coupling

Question 32

what are the general functions of the colon?

Answer 32

- water and electrolyte absorption - fermentation - storage of feces

Question 33

colonic motility facilitates ___ and thereby optimizes colonic functions.

Answer 33

mixing

Question 34

what are two structural specializations of the colon?

Answer 34

- haustra (saccules) | - segmentation

Question 35

what is colon mixing optimized by?

Answer 35

-haustra and segmentation

Question 36

what is a strong mixing property of the colon?

Answer 36

retropulsion

Question 37

what processes are influence by colonis motility?

Answer 37

- absorption | - fermentation

Question 38

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

Answer 38

transverse and descending

Question 39

the horse has a colonic pacemaker located near the _____

Answer 39

pelvic flexure (ascending colon)

Question 40

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

Answer 40

PS

Question 41

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

Answer 41

sympathetic

Question 42

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

Answer 42

- voluntary | - GSA pudendal nerve

Question 43

what is the glandular stomach of the avian?

Answer 43

proventriculus

Question 44

what is the muscular "gizzard" of the avian?

Answer 44

ventriculus

Question 45

what happens in the crop?

Answer 45

mucous secretion/storage of fod

Question 46

what happens in the paired ceca?

Answer 46

- urinary excretions | - reabsorption of water and electrolytes