electrical wave and stomach

• Most of GI contractions occurring rhythmically

• Not AP, slow changes in the resting membrane potential (5 – 15 MV); Unknown cause

Slow waves

how long does slow wave happen in stomach

3 min

how long does slow wave happen in terminal ileum

9 min

how long does slow wave happen in duodenum

12 min

Caused by complex interaction of smooth muscle and specialized cells Interstitial Cells of Cajal (ICC) which are electrical pacemaker of smooth muscle cells

slow waves

are electrical pacemaker of smooth muscle cells

Interstitial Cells of Cajal (ICC)

what should interact to cause slow waves?

smooth muscle cells and interstitial cells of cajal

these do not alone cause muscle contraction; excite intermittent spike potentials

slow waves

• True action potentials; lasts 10 to 20 milliseconds

• Occurs automatically when resting membrane potential

becomes more positive

• Controlled by the calcium-sodium channels, which are much

slower to open and close

• Tonic contractions: continuous repetitive spike potential by

hormones, or continuous entry of calcium

Spike Potentials

• True action potentials; lasts 10 to 20 milliseconds

Spike Potentials

• Occurs automatically when resting membrane potential

becomes more positive

Spike Potentials

• Controlled by the calcium-sodium channels, which are much

slower to open and close

Spike Potentials

• Tonic contractions: continuous repetitive spike potential by

hormones, or continuous entry of calcium

Spike Potentials

spike potentials last for?

10 to 20 milliseconds

spike potentials are controlled by?

calcium-sodium channels which are much slower to open and close

these are continuous repetitive spike potential by

hormones, or continuous entry of calcium

Tonic contractions:

• Located on the superior left side of the abdominal cavity

(~10 in long)

• When full holds about 1 gallon of food

• Food enters at the gastroesophageal/cardiac opening, surrounded by the cardiac (lower esophageal) sphincter

• Food exits at the pyloric sphincter (valve) between stomach

& small intestine

stomach