Studies on the motilty of isolated gut segments allow us to identify nerval reflexes and their neuropharmacology.
One of the main tasks of the gut is the mixing and transport of its contents. This is achived by a coordinated activity of the longitudinal and circular muscle layers. Contraction of the circular muscle constricts the gut while a contraction of the longitudinal muscle shortens a segment of the gut. Hardwired circuitry in the enteric nervous system is the basis for transport: Descending nerves release inhibiting neurotransmitters on the distal side of a stimulus. This leads to a relaxation of the circular muscle and a widening of gut lumen. Excitatory neurotransmitters which are released by ascending nerves on the proximal side of the stimulus lead to a contraction on this site. These cycles which are coordinated in time and space result in an anally directed transport of gut contents ("peristaltic reflex").
Transit of gut contents through this peristaltic reflex is regulated so that a maximum of nutrients can be extracted (Movie: Peristalsis). Noxious influences however can make a faster excretion necessary. In these cases a 'Powerperistalsis' achieves a highly accelerated transit (Movie: "Giant contractions").
- Effect of phytopharmaca on muscle preparations from guinea pig stomach.
- Functional importance of polarised enteric reflexes in the guinea pig stomach.