PHGY 210 Lecture Notes - Lecture 4: Resting Potential, Peristalsis, Stroke Volume
27 Nov 2015
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Document Summary
No peristalsis in the proximal region of the stomach. Peristalsis begins 1/3 of the way down the stomach. Gastrointestinal peristalsis: propagated contraction results from a series of local enteric reflexes in response to local distension. Amplitude - magnitude of stimulus (and interaction of neural and hormonal factors) Frequency - direction and velocity; electrical characteristics of smooth muscle. Electrodes in a muscle cell in the proximal region - steady resting membrane potential of ~60 mv: this resting potential is unstable, showing rhythmic depolarizations of 10-15 mv, they are independent of innervation. Down into the distal region, there is a series of rhythmic waves of partial depolarization at regular intervals of 20s. Electrodes around the circumference of the stomach will give the same pattern. These are slow waves, ber (basic electrical rhythm), or eca (electrical control activity) Electrodes along the longitudinal axis will detect the same rhythmic waves; but the signal appears to be migrating.
