GI 4

Question 1

Is swallowing initiation voluntary or involuntary?

Answer 1

voluntary

Question 2

3 Phases of Swallowing

Answer 2

1. Oral
2. Pharyngeal
3. Esophageal

Question 3

Oral phase

Answer 3

tongue push bolus to soft palate, triggers swallowing reflex

Question 4

Which of the three phases of swallowing is under voluntary control?

Answer 4

oral phase

Question 5

Pharyngeal phase

Answer 5

propel food bolus from mouth through pharynx to esophagus

Question 6

Esophageal phase

Answer 6

move bolus through esophagus to stomach

Question 7

Peristalsis

Answer 7

coordinated series of muscle constrictions and relaxations to create propulsive motility of the GI tract

Question 8

Area of constriction

Answer 8

part of peristalsis created by contractions of the inner circular muscle

Question 9

Dilation

Answer 9

part of peristalsis created by contractions of the outer longitudinal muscle

Question 10

What innervates striated muscle of the esophagus?

Answer 10

direct innervation by somatic motor fibers of the vagus nerve

Question 11

What innervates smooth muscle in the esophagus?

Answer 11

visceral (autonomic) motor fibers of the vagal nerve via myenteric plexus

Question 12

Functions of the Upper Esophageal (Cranial) Sphincter

Answer 12

deliver bolus to stomach under control of swallowing reflex; prevent air and reflux from entering upper esophagus

Question 13

Functions of the Lower Esophageal (Cardiac) Sphincter

Answer 13

prevent gastroesophageal reflux

Question 14

Sensory Nerve function in Control of Swallowing

Answer 14

in pharynx and esophagus, detect distention and low pH and communicate to the medulla (can also supplement the myenteric plexus)

Question 15

Medulla function in Control of Swallowing

Answer 15

tell respiratory center (also in medulla) to pause respiration; communicate with vagal nuclei to send motor signals

Question 16

Megaesophagus

Answer 16

generalized esophageal dilation and hypoperistalsis

Question 17

Achalasia

Answer 17

lower esophageal sphincter fails to undergo relaxation so contents can’t get into stomach

Question 18

Treatment for Megaesophagus?

Answer 18

Bailey chairs

Question 19

Functions of the Stomach (3)

Answer 19

1. Temporary food storage
2. Process food into a fluid consistency
3. Release fluid into the intestine at a controlled rate

Question 20

4 Parts of the Stomach

Answer 20

1. Cardiac part
2. Fundus
3. Body
4. Pylorus

Question 21

Proximal Region of the Stomach Function

Answer 21

store ingested food, tonic contractions

Question 22

Distal Region of the Stomach Function

Answer 22

break up, mix, and propel food; phasic contractions

Question 23

Fundic Accomodation

Answer 23

fundus expands in response to increased gastric pressure to prevent reflux

Question 24

retropulsion

Answer 24

occurs when peristaltic wave hits pyloric sphincter and ingesta is crushed and pushed back towards proximal stomach

Question 25

3 Locations that can trigger Fundic Accomodation

Answer 25

1. Mouth/Pharynx 2. Stomach 3. Small Intestine

Question 26

Fundic Accommodation at the Mouth/Pharynx

Answer 26

chewing/swallowing triggers vagovagal reflex; motor neuron releases ACh at the myenteric plexus, which in turn triggers the release of inhibitory NTs (NO and VIP) causing relaxation of the proximal stomach to decrease gastric pressure

Question 27

Fundic Accommodation of the Stomach

Answer 27

sensory neurons of the enteric nervous system detect stretch of the stomach wall, also causes release of NTs for additional relaxation of the proximal stomach; can also signal back to CNS

Question 28

Fundic Accommodations of the Small Intestine (2)

Answer 28

components of digestive products (fats, proteins) signal the release of CCK from enteroendocrine cells and tells a sensory neuron back to the dorsovagal complex to trigger one of the other responses; stretch of small intestine can also directly cause the release of NO and VIP

Question 29

Enterogastric Reflex

Answer 29

feedback loop due to a signal from the small intestine to cause an effect in the stomach

Question 30

What three environmental aspects in the duodenum could inhibit stomach emptying via the enterogastric reflex?

Answer 30

1. Low pH 2. High osmolality 3. Presence of Fat

Question 31

Migrating Motor Complex

Answer 31

takes effect during fasting (interdigestive phase) to clear all the residue in the GI tract, contractions throughout stomach with a wide open pyloric sphincter and relaxed duodenum

Question 32

Hormone involved in the Migrating Motor Complex?

Answer 32

Motilin

Question 33

Problems if gastric emptying is too slow?

Answer 33

vomiting, loss of appetite, early satiety, gastric ulcers; often due to obstructions at the gastric outlet (cancer, peptic ulcer disease) or problems with motor events in distal stomach

Question 34

Problems if gastric emptying is too fast?

Answer 34

diarrhea, duodenal ulcers