PHGY 210 Lecture Notes - Lecture 19: Pylorus, Vagotomy, Duodenum

• School: McGill University
• Department: Physiology
• Course: PHGY 210
• Professor: Ann Wechsler

Document Summary

Remember that the upper proximal stomach is for storage, while the lower distal stomach is for mixing. No peristalsis in the proximal stomach, gastric peristalsis starts 1/3 of the way on the distal stomach, moving down towards the sphincter. The gi peristalsis is propagated contraction caused by local enteric reflexes in response to local distension. The amplitude of the stimulus leads to increased magnitude of the contraction. Frequency, direction, velocity of the contraction are controlled by the electrical characteristics of the smooth muscle. Electrode testing in the proximal stomach measures a straight line, a steady electrical signal. If electrodes are in the distal stomach smooth muscles records an unstable resting membrane potential, 10-15mv in size, lasting 1 to 4 seconds each, recurring at regular intervals. All cells at the same level share the same synchronized rhythm, but if they are delayed on the longitudinal muscle fibres, the rhythm is the same, but there is displacement, like sequential activation.