Lecture 12.A. - GI Motility

Question 1

Muscles of the mouth and esophagus are controlled by the ____ ____.

Answer 1

Brain stem

Question 2

At rest, the pharyngeal muscle has very little tone, and the ___________ muscle closes the esophagus by pressing against the ______ cartilage.

Answer 2

Cricopharyngeal muscle

Cricoid Cartilage

Question 3

Swallowing occurs in 3 phases.

In the First phase, voluntary clenching of the mouth and pressing of the tongue against the hard palate pushes food back, pushing open the _____ palate.

In the Second phase, food stimulates _____ receptors in the Pahrynx –> this causes the Upper _____ sphincter to relax for 1 second and then contract forcefully before returning to baseline tone.

In the third phase, _____ _____ continues the contraction wave initiated by UES contraction all the way to the LES, which takes about 6-9s. The LES contracts for 1 sec then returns to base tone. Keep it mind the LES relaxes at the same time the _____ forcefully contracts in Phase 2.

Also keep in mind all three of these phases are controlled by the ______ center in the CNS.

Answer 3

Soft palate

Tactile receptors

Upper Esophageal Sphincter (UES)

Primary Peristalsis

UES

Swallowing center

Question 4

If primary peristalsis fails to push all of the food down, the esophagus initiates Secondary Peristalsis, which is ______ controlled and persists as long as food is present. Distention of the esophagus by the remaining food is detected by sensory neurons –> signal sent to the _____ plexus –> signal passed to interneurons –> Vagal Excitatory signal sent back to area above distention via the neurotransmitter _____ (causes contraction) AND Vagal inhibitory signal sent to area below distention via ____/____ (causes relaxation.)

Answer 4

Locally

Myenteric plexus

ACh

VIP/NO

Question 5

Both salivary and esophageal submucosal glands secrete _____ and _____ which help protect against acidic effects of reflux.

Answer 5

HCO3-

Mucus

Question 6

The ______ of the stomach is the most highly distensible section of the stomach. The ______ serves as a grinding chamber, undergoing phasic peristaltic contraction.

Answer 6

Fundus

Corpus

Question 7

_____ relaxation is the term used to describe relaxation of the stomach at the same time the _____ relaxes.

Answer 7

Receptive relaxation

LES

Question 8

There are _____ cells located in the greater curvature of the stomach, and they are responsible for regulating gastric peristalsis. Keep in mind the ______ does NOT contract.

Answer 8

Pacemaker cells

Fundus

Question 9

Rank the following in order of fastest to slowest gastric emptying:

Isotonic Saline

Hypertonic Saline

Acidic Saline

Meal rich in fats and protein

Answer 9

Isotonic > Hypertonic > Acidic > Fats and Protein

Question 10

Enterogastric reflex describes how the ____ of the stomach contracts less when contractility of the _____ increases in response to ACIDITY.

Answer 10

Antrum

Duodenum