GI Physiology: Motility Flashcards
How much liquid goes into the GI tract, how much comes out, and how much is absorbed in the large intestine?
Approximately 9 L goes in from ingestion and secretion, 100ml comes out in feces, and almost 1 L is absorbed in the large intestine.
All the sphincters are made up of smooth muscle except two. Which ones are they?
The upper esophogeal and external anal sphincters.
What two things does the upper esophogeal sphincter separate?
The mouth/pharynx from the esophagus.
What two things does the lower esophogeal sphincter separate?
The esophagus from the stomach.
What two things does the pyloric sphincter separate?
The stomach from the duodenum.
What two things does the sphincter of Oddi separate?
The pancreatobiliary ducts from the duodenum.
Which sphincter is the only sphincter in which food does not pass through?
The Sphincter of Oddi
What two things does the iliocecal sphincter separate?
The small intestine from the large intestine
When swallowing food, the ____ _____ closes to seal off the nasal passage, after which the ________ closes to seal off the trachea. This is under __________ control.
the soft palate closes to seal off the nasal passage, then the epiglottis closes to seal off the trachea.
Under involuntary control
Extrinsic innervation of the GI tract includes the ___________ and ___________ divisions of the autonomic nervous system. Intrinsic innervation is also called _________ innervation.
Extrinsic includes sympathetic and parasympathetic divisions of the ANS.
Intrinsic is also called enteric innervation.
Can the GI tract function solely via enteric innervation?
Yeah
Generally, what does sympathetic stimulation do to the GI tract? What about parasympathetic stimulation? What neurotransmitters are involved?
Sympathetic stimulation causes inhibition of GI secretion and motility and contraction of GI sphincters - norepinephrine is the NT.
Parasympathetic stimulation stimulates digestive activities. Ach is the NT.
In which histologic layer is the submucosal plexus found? What is its primary function?
It is found buried in the submucosa or in between the submucosa and circular muscle layer deep to it. Its function is to sense the lumenal environment to regulate GI blood flow and epithelial cell function.
In which histologic layer is the myenteric plexus found? What is its primary function?
Found between the inner circular and outer longitudinal layers of smooth muscle. Main function is to control GI motility.
Does the myenteric plexus tell GI smooth muscle what to do directly, or is there an interneuron involved?
There is an interneuron involved that integrates sensory information from the enteric plexuses and tells the smooth muscle what to do.
