Lectures 24 & 26: Enteric Nervous System Flashcards
True or false:
Smooth muscle once contracted can only be actively relaxed by removal of Ca2+.
False, actin-myosin cross-bridges don’t break when Ca2+ is removed. This requires the activity of inhibitory motor neurons.
True or false:
ENS contains its own sets of unique neurotransmitters exclusively found in the ENS.
False, most neurotransmitters and their receptors are found in ENS.
ENS contains how many ganglionated plexi?
Two: Myenteric (Auerbach’s) and Submucosal (Meissner’s)
Myenteric (Auerbach’s) plexus output and input
Provides motor innervation to both layers of the muscular layer of the gut, having both parasympathetic and sympathetic input
Location of the Submucosal (Meissner’s) plexus
the submucosa of the intestinal wall
True or false:
Submucosal (Meissner’s) plexus contains only sympathetic fibres.
False, it contains only parasympathetic fibres.
Output of the submucosal plexus
Provides secretomotor innervation to the mucosa nearest the lumen of the gut
The nerves of Meissner’s plexus are derived from
The nerves of this plexus are derived from the myenteric plexus which itself is derived from the plexuses of parasympathetic nerves around the superior mesenteric artery.
Function of the myenteric plexus
Myenteric plexus controls the function of contractile activity of the gut wall
Where does the myenteric plexus ‘begin’?
Ganglionated myenteric plexus begins at upper oesophageal sphincter
Ganglionated submucosal plexus begins at
pylorus
Function of the submucosal plexus
Regulator/output component of control of water, salt secretion into the lumen of the gut
True or false:
Sympathetic nerves innervate whole length of GI tract
True.
Dorsal root ganglion cell afferents run in which nerves?
splanchnic and pelvic nerves
True or false:
Intestinal contractions require input from regulatory centres higher up in the CNS.
False. Contractions of intestinal smooth muscle do not depend on the brain or spinal cord.
