GI Motility Flashcards
What is the major site of DIGESTIVE & ABSORPTIVE processes?
Small Intestine
Describe the muscle types involved in the digestive tract as you move down the esophagus
Starts as skeletal, third of the way down is mixed with smooth, then after halfway is all SMOOTH
Job of Epithelium and mucosa surrounding the lumen?
Secretions & Absorption
Job of the circular and longitudinal muscles of the gut?
motility
What Accessory organs provide secretions into the digestive tract?
Pancreas & Liver
Facing the lumen are elaborate folds of ________ all lined with __________ cells.
VILLI, EPITHELIAL
What is the name of the 1st layer of muslce which is associated with the shape/SA of mucosa itself?
Muscularis Mucosa
What is the name of the 2nd layer of muscle which contains the circular and longitudinal muscles?
Muscularis Externa
What Nervous system is exclusive to the gut?
Enteric
The Enteric NS has 2 plexi, what are their names and what do they serve?
- Submucosal plexus –> submucosa and muscularis mucosa, 2. Myenteric plexus –> circular and longitudinal smooth muscle layers
Which nerve plexus is innervated by the ANS?
trick, they both are!
Sensory cells located in the epithelium feedback and target where?
Back to the brain but also to the 2 plexi in the Enteric NS
The Myenteric plexus is sandwiched by the 2 smooth muscle layers, which is closest to the lumen of the GI Tract?
Circular
Which smooth muscle is in charge of determining the depth of the rugae and convolutions of the mucosa?
Muscularis mucosa
Parasympathetic innervation on the Enteric NS is pre or post ganglionic?
PRE
Sympathetic innervation on the Enteric NS is pre or post ganglionic?
Mostly post
If parasympathetic innervation, the NT between pre ganglionic and post is?
ACh on nicotinic receptors.
Then these cells would release ACh onto muscarinic receptors to ever where they would be.
Sympathetic is already postganglionic, so the NT being released will be:
NE on adrenergic receptors (alpha1, alpha2, beta1, beta2)
The afferent information that is collected by sensory cells in the mucosa epithelia that is FEEDING BACK TO THE ENTERIC NS, is called:
the SHORT LOOP (local)
Afferent input from the mucosa that is FEEDING BACK to the BRAIN is called what? and does what?
the LONG LOOP - changes the balance between sympathetic and parasympathetic.
The sensory neurons in the mucosa have what kind of receptors to sense conditions?
Osmoreceptors and chemoreceptors
What nerves are supplying the autonomic input to the gut and where?
From epiglottis –> Left colic flexure = VAGAL, from there on = SACRAL SPINAL CORD
In general what is the Parasympathetic innervation doing in the gut?
INCREASE motility, RELAX sphincters, STIMULATE secretions
In general, what is the Sympathetic Innervation doing in the gut?
DECREASE motility, CONTRACT sphincters, INHIBIT secretions
What NTs are released by sensory neurons in mucosa which feedback on the SHORT LOOP to EXCITE enteric interneurons?
Substance P, CGRP
What NTs are released between ascending and descending interneurons in the MYENTERIC PLEXUS?
ACh, Serotonin (5-HT)
What NTS are released by secretomotor neurons in the mucosa that target the Submucosal plexus?
ACh, VIP
What do the chemoreceptors in the mucosa sense?
Osmolality, acid, nutrients
Motor neurons on the smooth muscle can be Excitatory or Inhibitory depending on what they release:
NO –> dilate –> INHIBIT, ACh –> constrict –> EXCITE
What kind of cells provide pacemaker activity to ENS?
Interstitial cells of CAJAL (ICC)