Activity of Gastrointestinal Smooth Muscle

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INTRODUCTION
Give a brief description in your own words of the objectives and aims of this practical. The aim of this practical is to investigate how the autonomic nervous system (ANS) affects the motility in the gastrointestinal tract, by experimenting with the release of neurotransmitters.

A. RESPONSES TO NERVE STIMULATION
 Attach a copy of your experimental recordings showing a period of spontaneous contractions and the response to stimulating the nerves at 20 Hz with both a voltage that produced only a modest response and the voltage that produced the maximal response.

1)Briefly describe the response of the ileum when it is unstimulated and during stimulation of the nerves. It is shown that the rabbit ileum has a constant rate of contractions and relaxations, when it is not stimulated. However there is a significant drop in the amplitude of the contractions, when the ileum is stimulated. This is due to higher voltage having higher inhibition, resulting in greater reduction in the response.

2) What is the frequency of the regular spontaneous contractions of the ileum? What causes these spontaneous contractions?

 Attach a copy of your experimental recordings showing the response to stimulating the nerves with the maximal voltage at both 5 Hz and 50 Hz.

3)Explain the effect of altering stimulus frequency on the response of the ileum to nerve stimulation.

B. MIMICKING THE ACTION OF THE AUTONOMIC NERVOUS SYSTEM USING DRUGS  Attach copies of your experimental recordings showing the response of the ileum to the direct addition of noradrenaline and of acetylcholine to the tissue bath.

1)What was the final bath concentration of noradrenaline you used? Briefly describe the response of the ileum to the direct addition of noradrenaline.

2)What was the final bath concentration of acetylcholine you used? Briefly describe the response of the ileum to the direct addition of...
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