Intro to GI and Esophageal Motility Module (Quiz) Flashcards
GI tract innervated by which nervous system
- autonomic
autonomic nervous system divided into
- extrinsic
- enteric
extrinsic nervous system divided into
- parasympathetic
- sympathetic
the enteric nervous system is connected to the
but can function
- CNS
- can also function autonomously
two networks for the enteric nervous system
- myenteric plexus
- submucousal plexus
which plexus is located between the outer longitudinal and middle circular muscle layers
- myenteric plexus
which plexus is located between the middle circular layer and the mucosa
- submucousal plexus
which plexus controls motor function of the longitudinal and circular smooth muscle layers
- myenteric plexus
which plexus controls intestinal secretion
- submucous plexus
in the ______ plexus, excitatory motor neurons stimulate smooth muscle contraction primarily through release of _________ and inhibitory motor neurons stimulate relaxation primarily though release of _________
- myenteric plexus
- excitatory - acetylcholine
- inhibitory - nitric oxide
the __________ plexus innervates the glandular epithelia, intestinal endocrine cells, and submucosal blood vessels to regulate intestinal secretion
- submucousal plexus
parasympathetic innervation of the GI tract is supplied primarily by which nerves
- vagus nerve
- pelvic nerves
preganglioninc efferent parasympathetic fibers project to the cholinergic neurons within the myenteric and submucous plexuses of the enteric nervous system to cause smooth muscle ___________
- contraction
the preganglionic vagal fibers project to enteric neurons where
- esophagus
- stomach
- small intestine
- colon
efferent fibers in the pelvic nerves project to enteric neurons where
- colon
- rectum
vagal nerve signals are primarily mediated through the release of
- acetylcholine
parasympathetic inputs in the esophagus and stomach result in contraction or relaxation?
- both
- controls excitatory or inhibitory motor neurons
parasympathetic projections to the small and large intestine result in contraction or relaxation?
- contraction
- controls excitatory motor neurons
sympathetic input in the enteric nervous system does what
- shunt blood from splanchnic to systemic circulation
- suppress digestive function
sympathetic input mediated primarily through which neurotransmitter
- norepinephrine
sympathetic input acts directly on sphincteric muscles to ________ tone, keep the sphincter ________ and ________ GI motility through presynaptic _________ of enteric motor neurons
- increase tone
- keep sphincter closed
- decrease GI motility
- through presynaptic inhibition
peristalsis is an organized reflex response initiated when
- gut wall stretched by luminal contents
wall stretch initiates ________ of the circular muscle and ________ of the longitudinal muscle in the propulsive segment
- contraction of circular muscle
- relaxation of longitudinal muscle
wall stretch initiates ________ of the circular muscle and ________ of the longitudinal muscle in the receiving segment
- relaxation of circular muscle
- contraction of longitudinal muscle
wave of perastalsis moves in an _____ to _____ direction
- oral to caudal
while peristaltic activity can be increased or decreased by the parasympathetic and sympathetic stimuli its occurrence is ________ of extrinsic innervation
- independent of
what is trituration
purpose
- crushing and grinding ingested food by the stomach
- decreases particle size and increases surface area to improve efficiency of digestive enzymes in the small intestine
what do mixing movements do
- blend secretions with nutrients in the small intestine to promote increased contact with mucosal surface to facilitate nutrient absorption
the prototypic mixing pattern is termed
- segmentation
prototypic mixing movement involves a repetitive pattern of ___________ propulsion into _______ receiving segments that facilitate stirring and mixing of chyme
- repetitive pattern of bidirectional propulsion into relaxed receiving segments
reservoir functions are performed by
- stomach and colon
which sphincter is located at the junction of the posterior oropharynx and proximal esophagus
- upper esophageal sphincter
function of upper esophageal sphincter
- prevents retrograde flow of GI contents
- prevents passage of air into esophagus
which sphincter is located at the junction of the distal esophagus and proximal stomach
- lower esophageal sphincter
function of lower esophageal sphincter
- prevents reflux of gastric contents into esophagus
in the absence of a hiatal hernia, the lower esophageal sphincter is located in the
- diaphragmatic hiatus
what is located at the junction of the distal stomach and duodenal bulb
- pylorus
function of pylorus
- gastric emptying
- prevents reflux of bile acid and pancreatic enzymes into the stomach
which sphincter is located at the level of the duodenal ampulla where both the pancreatic and common bile ducts insert in the duodenum
- sphincter of Oddi
function of sphincter of Oddi
- prevents reflux of small bowel chyme into bile and pancreatic ducts
- participates in maintenance of sterility of pancreatic and biliary trees
which sphincter is located at the junction of the terminal ileum and cecum
- ileocecal valve
function of ileocecal valve
- prevents reflux of colonic contents into small bowel
- limits small bowel bacterial overgrowth
which sphincters are located at the proximal and distal aspects of the anal canal
- internal and external anal sphincters
function of internal and external anal sphincters
- maintain fecal continence
division of esophagus
- upper esophageal sphincter
- esophageal body
- lower esophageal sphincter
proximal 1/3 of esophagus composed of ________ muscle
distal 2/3 of esophagus composed of _______ muscle
- striated
- smooth
the upper and lower esophogeal sphincters remain ________ which ________ influx of air and reflux of gastric contents into esophagus while the esophageal body is _________ when not involved in the act of _________
- sphincters remain contracted
- prevents influx of air
- esophageal body is relaxed
- when not involved in swallowing
primarily peristalsis is initiated by
- voluntary act of swallowing
secondary peristalsis occurs when
- primary peristaltic event fails to clear bolus from body of esophagus
secondary peristalsis initiated by action of
- mechanoreceptors
at the onset of the swallow, the lower esophageal sphincter ________ which corresponds to a ________ in pressure across the sphincter which lasts until
what is this also called
- relaxes
- fall in pressure
- lasts until esophagus empties its contents into the stomach
- deglutitive relaxation of the LES
coordination of the peristaltic wave and relaxation of the lower esophageal sphincter is mediated by ______ nerve signals
- mediated by vagal nerve signals
