circular and longitudinal smooth muscle coats

small, spindle, shaped cells connected to each other forming bundles with cross connections to neighbouring bundles

the bundle rather than the individual muscle cell forms the basic unit for propagation of action potentials

GIT muscle usually shows rhythmic changes in membrane potential with a frequency of 3-15 cycles/min (slow wave

The presence of slow waves causes the bundles to be partly scontracted generating the muscle tone

Once threshold potential is reached, there is initiation of action potential resulting in complete muscle contraction

If the muscle bundles are hyperpolarised, slow waves disappear and tone diminishes leading to paralysis

Each bundle has its own slow-wave frequency, but as adjacent bundles are connected, the rhythm of the fastest bundle takes over - pacemaker.