GI Tract

Question 1

what does the enteric nervous system control

Answer 1

controls GI motility and secretion

Question 2

What 2 interconnected plexuses are in the gut wall and what do they control

Answer 2

Myenteric-motility

submucosal- secretions and local blood flow

Question 3

The ENS has reflex contractions in response to local stimuli which are?

Answer 3

stretch, nutrients, irritation and hormones

Question 4

What effect does parasympathetic innervation have

Answer 4

Excitatory to motility and secretion

Question 5

what effect does sympathetic innervation have

Answer 5

inhibitory to motility and secretion

Question 6

What are the two types of electrical activity in the gut smooth muscle cells

Answer 6

slow waves and spike potentials

Question 7

describe slow waves

Answer 7

provide a basic electrical rhythm via interaction with interstitial cells of cajal

Question 8

describe spike potentials

Answer 8

causes contraction by further depolarisation to threshold levels

Question 9

What are the two types of contractions

Answer 9

segmentation- back and forth pendular movements, for mixing

peristalsis- wave of contraction- for propulsion

Question 10

Give an example of ENS innervation dysfunction

Answer 10

Hirschsprung’s disease= absence of myenteric plexus resulting in aganglionic section of colon lacking peristalsis

Question 11

what are the 3 stages of swallowing (deglutition)

Answer 11

Oral, pharyngeal and oesophageal

Question 12

Give an example of Oesophageal motility dysfunction

Answer 12

Gastro-oesophageal reflux: LOS tone lost leading to flow of acidic gastric contents into oesophagus, results in inflammation and ulceration.

Question 13

What are the 3 primary motor functions of the stomach

Answer 13

storage: vagovagal reflex mediates receptive relaxation to allow reservoir function
mixing: breaking down food and mixing it with gastric juice for digestions

emptying contents into duodenum at a controlled rate.

Question 14

What controls the emptying of the stomach

Answer 14

excitatory -stimulated by motilin and PSMNS

Inhibitory- Via CCK, ANS (stimulation)

Question 15

Name 3 propulsive peristalsis reflexes

Answer 15

gastroenteric reflex
gastroileal reflex
migrating motor complex

Question 16

describe the gastroenteric reflex

Answer 16

gastric distention activates myenteric plexus to promote SI peristalsis

Question 17

describe the gastroileal reflex

Answer 17

gastric distention promotes peristalsis in ileum to force chyme via ileocaecal valve into caecum

Question 18

describe the migrating motor complex

Answer 18

series of peristaltic contractions, between meals, every 90 min sweeps contents into the colon.

Question 19

name 3 disruptions to peristalsis

Answer 19

peristaltic rush, paralytic ileus and vomiting

Question 20

describe the peristaltic rush

Answer 20

mucosal irritation, ENS and ANS reflexes which rapidly sweeps contents of SI into colon

Question 21

describe the paralytic ileus

Answer 21

loss of peristalsis following mechanical trauma

Question 22

describe the defacation reflex

Answer 22

mass movement pushes shit into the rectum, stretch receptors are stimulated and activate the ENS & PSM ANS, involuntary contraction of muscle in the rectum opening internal anal sphincter. external anal sphincter is voluntarily relaxed to allow defacation.