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Enteric System
N/A
56
Physiology
Graduate
11/27/2011

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Term
When isolated from CNS input, what is the enteric system still capable of?
Definition
Coordinate basic reflexive functions of secretion, absorption, mixing, and movement from luminal contents
Term
Auerbach's plexus is another name for what?
Definition
Myenteric Network
Term
Meissner's Plexus is another name for what?
Definition
Submucosal Plexus of the Gut Wall
Term
The Myenteric network extends through what structures?
Definition
Entire GI Tract
Term
The Submucosal Plexus travels through what structures?
Definition
Small and Large Intestines
Term
How are plexuses organized in the Enteric System?
Definition
As Ganglia
Term
What interconnects ganglia and plexuses?
Definition
Nerve bundles
Term
What characterizes the axons of the Enteric System?
Definition
Thin and unmyelinated
Term
The Enteric System contains what kinds of cells also found specifically in the Central Nervous System?
Definition
Glia
Term
Intrinsic Projection involeves what type of neurons?
Definition
Intrinsic Primary Afferent Neurons (IPAN)
Term
Projection is via which root?
Definition
Dorsal Root
Term
What kind of ganglion are involved in nociceptive projection?
Definition
Sympathetic Ganglion
Term
What does SAC stand for and where are they found?
Definition
Stretch Activated Channels, found in Smooth Muscle
Term
What is the result of the activation of SACs?
Definition
Induces depolarization and contraction of smooth muscle
Term
Epithelial Cells in the GI tract respond to what kinds of signals?
Definition
Luminal pH, inorganic acids, short chain fatty acids, toxins, etc.
Term
How do intermediary epithelial cells in the GI respond to signals?
Definition
Secretion of 5-HT (serotonin) which activates sensory cells
Term
Sensory cells in the GI tract are Polymodal, meaning what?
Definition
Respond to multiple stimuli types
Term
Excitatory motoneurons in the GI use what neurotransmitters?
Definition
Ach and Tachykinin
Term
Inhibitory motoneurons use what neurotransmitters?
Definition
NO, ATP, Vasoactive Intestinal Peptide, Pituitary Adenyle Cyclase Activating Peptide
Term
How are muscle membrane potentials characterized in most GI muscle?
Definition
Slow waves of depolarization followed by hyperpolarization
Term
What sort of depolarization is required for contraction of GI muscles?
Definition
Spiking depolarization
Term
What is the basis of depolarization/hyperpolarization waves in GI muscle cells?
Definition
Interactions with interstitial cells of Cajal
Term
The pacemaker cells of the GI are known as what?
Definition
Interstitial Cells of Cajal (ICC)
Term
Where are ICCs located?
Definition
Interposed between Motoneurons and Muscle
Term
Excetions in exocrine glands and GI cells are dependent on water from where?
Definition
Blood
Term
What are Crypts of Lieberkuhn?
Definition
Enzymatic secretory glands found in the intestinal lining of the small intestine and colon
Term
Innervation of Crypts of Lieberkuhn causes the gland to secrete what?
Definition
CL-
Term
Gastric Acid secretion in the stomach is induced by what?
Definition
Actions of Secretomotor cells on Parietal Cells
Term
Describe the action of circular muscle transmitting a bolus of food in the GI tract
Definition
Muscles above contract, muscle below relax, pushing the bolus down
Term
What is the response of IPANs to distension?
Definition
Activation of a chain of ascending and descending interneurons
Term
Ascending neurons activated by IPAN perform what function?
Definition
Contacts excitatory motoneurons that induce contraction of circular muscle via ICC
Term

Descending neurons activated by IPAN perform what function?

Definition

Contacts inhibitory motoneurons that induce relaxation of circular muscle via ICC

Term
How do enteric neurons affect propulsive movements in the esophagus?
Definition
Synpapses on the motor end plate modulate synaptic activity of skeletal muscles controlled by somatic neurons
Term
What nerve innervation is responsible for expansion of the stomach?
Definition
Parasympathetic Vagus Nerve
Term
While frequency of peristalsis is due to vagal imput, peristalsis amplitude is due to what?
Definition
Both Vagus and Enteric
Term
Secretomotor activity is caused by what?
Definition
Distention and chemical stimulus due to food bolus
Term
What kind of interneurons activate secretomotor neurons?
Definition
Descending interneurons activated via IPAN
Term
Secretomotor neurons perform what function?
Definition
Induce vasodilation and CL- secretion into the lumen, inducing water movement into the lumen
Term
What is the result of noxious stimulus in the GI?
Definition
Activate IPAN, induces CL- secretion, causes massive fluid loss via diarrhea 
Term
What modulates strength and frequency of waves in the small and large intestines?
Definition
Enteric System
Term
Lower esophageal is largely but not exclusively controlled by what?
Definition
Vagus
Term
External Anal Sphincter is regulated by what?
Definition
Somatic System
Term
The Enteric Nervous System controls all sphincters except for what?
Definition
Lower Esophageal and External Anal Sphincter
Term
The Sphincter of Oddi serves what purpose and is controlled by what?
Definition
Controls the passage of bile from the gallbladder and pancreatic secretions into the duodenum, regulated by Enteric Nervous System
Term
Preganglionic Parasympathetic cells via Vagus and Pelvic Nerve in the Enteric NS are what kind of neurotransmitter neurons?
Definition
Cholinergic
Term
Sympathetic cells in the Enteric NS are what kind of neurons?
Definition
Noradrenergic
Term
Sympathetic stimuli in the enteric system generally induces what type of response?
Definition
Vasoconstriction
Term
Sympathetic secretion inhibitors and motility inhibitors are modulated by what?
Definition
Intestinofugal sensory neurons projecting into prevertebral ganglion
Term
What is the prevalent symptom in Hirschsprung's Disease?
Definition
Severe constipation among infants
Term
What causes Hirschsprung's Disease?
Definition
Mutation results in failure of neurons to develop in distal part of the bowel
Term
What is the primary treatment option of Hirschsprung's Disease?
Definition
Removal of affected part of the bowel
Term
What is the prevalent symptom of Irritable Bowel Syndrome?
Definition
Abdominal pain, altered bowel motility manifesting as constipation, diarrhea, or fluctuations between the two
Term
What causes irritable bowel syndrome?
Definition
Hyperactivity of sensory fibers
Term
What is the most common treatment for Irritable Bowel Syndrome?
Definition
No effective treatment exists
Term
What causes Opoid Induced Dysfunction?
Definition
Numerous cell expression of opioid transmitters, decreasing cholinergic release by motorneurons with opioid receptors upon endogenous opioid release
Term
What is the effect of opioid induced dysfunction?
Definition
Exogenous opioids such as morphine given for pain management results in inhibition of propulsion of bolus along intestines
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