Gastrointestinal smooth muscle

The Autonomic Nervous System (ANS) responds to the external and internal environment to regulate the motility (i.e. contractions) in the gastrointestinal tract (GI-tract). Information is taken in via sensory nerves, analysed and integrated mainly (though not exclusively) in the central nervous system. Contraction is achieved via the actions of efferent nerve fibres terminating on smooth muscle in the GI-tract. In this set of simulations we will study how the ANS controls intestinal motility, both by activating the nerve fibers and by mimicking nerve activation using specific neurotransmitters (agonists) that act on receptors in the smooth muscle membrane. We will also learn to block transmitter action on smooth muscle with specific drugs (antagonists) that inhibit these receptors.

The preparation consists of a short length of rabbit ileum together with its extrinsic nerve supply. Watch the video for a schematic and explanation of the preparation.

Because the longitudinal muscle of the ileum contracts spontaneously at a very regular rate, we will use the amplitude of these baseline contractions as the "benchmark" against which to examine the effects of activating the nerves or of mimicking the actions of the neurotransmitters released by the autonomic nerves in the ileum.

Navigate through the tabs on the top banner to see videos of the actual experimental setup, read instructions on how to measure the contraction amplitude, perform the simulation that will allow you to explore the effects of agonists and antagonists on the contraction amplitude, and study a schematic of what's going on at the synaptic level.