GI tract motility

Question 1

what is the inner smooth muscle layer of the stomach

Answer 1

oblique

Question 2

what is the middle smooth muscle layer of the stomach

Answer 2

circular

Question 3

what is the outer smooth muscle layer of the stomach

Answer 3

longitudinal

Question 4

where does the muscle wall thickness increase

Answer 4

proximal to distal

Question 5

where do contractions happen to mix food and propel it to the small intestine

Answer 5

caudad region

Question 6

what are the 3 layers of the stomach wall

Answer 6

serosa
muscularis externa
rugae of mucosa

Question 7

how does the PSNS affect the stomach

Answer 7

increases muscle contractions and secretion

Question 8

what is the parasymp supply to the stomach

Answer 8

vagus

Question 9

what is the symp supply to the stomach

Answer 9

coeliac ganglion

Question 10

where are the sensory afferent fibres to the stomach

Answer 10

between the sensory receptors and the ENS and centrally via the vagal and splanchnic nerves

Question 11

what are the orad and caudad regions of the stomach

Answer 11

orad- towards the mouth

caudad- towards the feet

Question 12

what does distension of the lower oesophagus induce

Answer 12

relaxation of the lower oesophageal spincter and orad

Question 13

what afferent information is relayed from the stomach

Answer 13

mechanoreceptors associated with chewing and distension

via sensory neurones

Question 14

what neurotransmitter causes orad relaxation when released from post gangionic peptidergic vagal neurones

Answer 14

vasoactive intestinal peptide

Question 15

how does the caudad contract

Answer 15

contraction waves begin in the middle and move towards the pylorus

Question 16

what is retropulsion

Answer 16

moving the gastric contents up for further mixing

Question 17

describe slow waves

Answer 17

generated by the interstitial cells of Cajal

when slow waves reach a certain potential then then L type ca channels open and contraction can occur

Question 18

what stimulates action potentials in slow waves

Answer 18

stretch
ach
parasympathetics

Question 19

what stimulates hyperpolarisation of smooth muscle

Answer 19

norepinephrine

sympathetics

Question 20

how does the para and sympa NS innervate the stomach

Answer 20

sympa - coeliac ganglion

para- vagua

Question 21

where is the submucosal plexus

Answer 21

between the muscularis mucosa and the submucosa

Question 22

where is the myenteric plexus

Answer 22

between the circular and longitudinal muscle layers

Question 23

what is the vagovagal reflex

Answer 23

controls relaxation of the stomach in response to food

Question 24

what are the three movement patterns in the stomach

Answer 24

propulsion
grinding
retropulsion

Question 25

what factors increase action potential frequency from slow waves

Answer 25

Parasympathetic stimulation, gastrin and motilin

Question 26

what factors decrease action potential frequency from slow waves

Answer 26

Sympathetic stimulation and secretin

Question 27

what hormone mediates migrating myoelectric complexes

Answer 27

motilin

Question 28

what is the frequency of slow waves in the ileum

Answer 28

9 per minute

Question 29

how often do MMCs happen

Answer 29

every 90 minutes to clear the small intestine of chyme

Question 30

what hormones stimulate orad contraction

Answer 30

ACh and substance P

Question 31

what substances control caudad contration

Answer 31

VIP nitric oxide

Question 32

what muscle is found in the large intestine

Answer 32

circular and longitudinal (tenia coli)

Question 33

what do pelvic nerves do to the distal colon

Answer 33

stimulate expulsive contrations

Question 34

how many times a day do mass movements of the large intestine occur

Answer 34

1-3 times | final movement propels faeces into the rectum

Question 35

what reflexes cause mass movements

Answer 35

gastrocolic and duodenocolic | this is because food further up the tract increases movement in the colon

Question 36

what do CCK and gastrin do in the gastrocolic reflex

Answer 36

efferent limb of reflex

Question 37

what is the rectosphincteric reflex

Answer 37

the relaxation of the internal anal sphincter