Activity of Gastrointestinal Smooth Muscle: Worksheet
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Referring to Figure 1 and Table 1, briefly describe the response of the spontaneously
contracting ileum to nerve stimulation. Was this response altered by increasing the voltage of nerve
stimulation?
2) What is the frequency of the regular spontaneous contractions of the ileum (measured in
contractions per minute)? What causes or initiates these spontaneous contractions?
[Maximum 100 words]
There is increased contraction amplitude at first but it gradually decreases in the later half as seen
in Fig. 1, whereas an overall decreased contraction amplitude was seen in Table 1. As pacemaker
cells will cause contractions upon nerve stimulation which leads to decreasing contraction
amplitude from the release of neurotransmitters in sympathetic nerve terminal. Yet, increasing
amplitude at the beginning suggested that a larger proportion of parasympathetic nerve fibers is
present in this extrinsic nerve than sympathetic nerves, because of the release of acetylcholine
which caused an excitatory response. And later decrease in amplitude is due to sympathetic nerves
being more active than parasympathetic nerves.
This response was altered by increasing the voltage of nerve stimulation, there was no significant
observation in contraction amplitude upon 4 or 8V. Thus, voltage has been increased to 10V and
the above observation was concluded.
Bench 15.adicht
Ileum Contractility (mV)
Stimulator On 20Hz, 10V, 1ms
Stimulator Off 20Hz, 10V, 1ms
1:01:40 1:01:45 1:01:50 1:01:55 1:02:00 1:02:05 1:02:10 1:02:15 1:02:20 1:02:25 1:02:30 1:02:35 1:02:40 1:02:45 1:02:50 1:02:55 1:03:00 1:03:05 1:03:10 1:03:15 1:03:20 1:03:25 1:03:30 1:03:35 1:03:40 1:03:45 1:03:50 1:03:55 1:04:00 1:04:05 1:04:10 1:04:15
11/08/2015