Changes

Therefore the ENS provides the GI tract with a certain degree of self-regulation, although most of these short reflex arcs provide a stimulatory influence, utilising acetylcholine. Some inhibitory reflexes do exist within the ENS including sphincter relaxation.

Therefore the ENS provides the GI tract with a certain degree of self-regulation, although most of these short reflex arcs provide a stimulatory influence, utilising acetylcholine. Some inhibitory reflexes do exist within the ENS including sphincter relaxation.

===GI Tract: Long Reflex Arcs===

===GI Tract: PNS Long Reflex Arcs===

Within the PNS, activity in the GI tract is also regulated via longer reflex arcs that are made up of preganglionic parasympathetic fibres from the CNS.  

Within the PNS, activity in the GI tract is also regulated via longer reflex arcs that are made up of preganglionic and postganglionic parasympathetic fibres from the CNS. The majority of the sensory cells within these long reflex arcs have sensory nerve endings within the digestive tract, although other senses including sight and smell can also exert an affect on the activity of the GI tract. Within the long reflex arcs, most postganglionic fibres are actually part of the GI tract internal nerve plexuses and the preganglionic nerves mainly run in the vagal nerve. Most postganglionic parasympathetic neurons release acetylcholine from their nerve endings, stimulating both secretion and motility. As mentioned within the SNS section above, long reflex arcs associated with the SNS system generally inhibit secretion, motility and decrease blood supply to the digestive tract.

These long reflex arcs primarily act to coordinate and regulate the activity of different sections of the GI tract. The PNS long reflex arcs are mainly involved in preparing sections for activity as they are mainly stimulatory. An example of this would be that the mastication of food stimulates salivary secretion but also secretion of gastric juice, pancreatic juice and bile.  

[[Category:Nervous System - Anatomy & Physiology]]

[[Category:Nervous System - Anatomy & Physiology]]

[[Category:To Do - A&P]]

[[Category:To Do - A&P]]