Esophagus physiology Flashcards
How many nuclei do smooth muscle cells have?
One
Do GI smooth muscle cells have sarcomeres?
No
This type of muscle cell does not have sarcomeres
GI smooth muscle
This type of muscle cell acts as a unitary, in which gap junctions permit coordinated contraction
GI smooth muscle
This type of muscle cell does not need innervation for contraction
GI Smooth muscle
(stimulus is stretch)
This movement in the GI tract increases surface area
Mixing movements
GI propulsive movements requires this to be intact
Myenteric plexus
During peristalsis, excitation of motor neurons (Ach, substance P) contracts this muscle
Circular smooth muscle
During peristalsis, excitation of inhibitory motor neurons (NO, VIP) relaxes this muscle
Longitudinal smooth muscle
Peristalsis mostly occurs by the action of this smooth muscle
Circular muscle
(Longitudinal muscle shortens the distance between points - not a significant role in peristalsis)
This type of muscle in the esophagus requires neural input
Striated (skeletal) muscle
CNS is required for peristalsis in this part of the esophagus
Upper and middle 2/3
(due to skeletal muscle required CNS)
CNS is not required for peristalsis in this part of the esophagus
Myenteric plexus is instead requires
Lower 1/3
(due to being composed of smooth muscle)
During swallowing, does the movement of food to the pharynx increase or decrease pressure at the Upper esophageal sphincter?
Increases
(This primary peristaltic wave causes the UES to open and food moves into esophagus)
During swallowing, as a bolus of food reaches the lower esophageal sphincter, does it relax or contract to allow food into the stomach?
Relaxes
The nucleus ambiguus innervates this part of the esophagus
Skeletal muscle and mixed areas
(Upper and middle 2/3)
The dorsal motor nucleus innervates this part of the esophagus
Smooth muscle
(lower 1/3)
Does sympathetic ganglia play a role in GI motility?
No - mostly a sensory role, also in blood flow
Is peristalsis in the striated muscle portion of the esophagus a gravity event?
NO - is due to circular muscle action
Does the dorsal motor nucleus play a role in motility of smooth muscle?
No - CNS is NOT required for peristalsis in smooth muscle portion of esophagus
The myenteric plexus is key for peristalsis in this part of the esophagus
Smooth muscle part (lower 1/3)
Is peristalsis in smooth muscle of the esophagus a gravity event?
No - mostly a circular muscle event
Is esophageal peristalsis in the striated or smooth muscle portion a circular muscle event?
BOTH
Latency in contraction of circular muscle is related to release of this molecule
NO (nitric oxide)
Duration (on) response of longitudinal muscle is due to this molecule
Acetylcholine
Relaxation of the lower esophageal sphincter (during peristalsis) is due to this compound, via the myenteric plexus
Nitric oxide (NO)
Does the Myenteric plexus release excitatory or inhibitory neurotransmitters?
Both
Propagation of peristaltic wave is related to this gradient
Latency gradient
Is the lower esophageal sphincter typically under low or high pressure?
High
Relaxation of the lower esophageal sphincter can be inhibited by compound
Tetrodotoxin (TTX)
Is the opening or closing of the lower esophageal sphincter due to neural activity (via nitric oxide)?
Opening
Is the opening or closing of the lower esophageal sphincter due to intrinsic activity of smooth muscle?
Closing
In achalasia, there is damage to this structure, resulting in loss of nitric oxide (and subsequent inability to relax LES)
Myenteric plexus
This pathology is sometimes also called hypertensive peristalsis
Is very painful, hard to localize (visceral)
Angina-like pain
Diffuse esophageal spasm
Nutcracker esophagus occurs at this part of the esophagus
Distal (smooth muscle portion)
Diffuse esophageal spasm, as well as Nutcracker esophagus, can be treated with these 3 types of drugs
Calcium channel blockers
Nitroglycerin
Botox
Regurgitated food from this part of the body will have a tart taste
Stomach
(due to acid)
Regurgitated food from this part of the body will have a putrid taste
Esophagus
(as seen in GERD)
This condition may present with esophageal distention, dysphagia, vomiting, and aspiration pneumonia
Achalasia
Is diffuse esophageal spasm painful?
YES - angina-like pain; mimics an MI
Is Achalasia painful?
Not usually
Metaplastic (abnormal) change in mucosa of esophagus due to adaptation to acid reflux
Occurs in many patients with GERD, starting at gastroesophageal junction
Increases the propensity for esophageal adenocarcinoma
Barrett’s esophagus
