Question

Which cells are referred to as pacemaker cells in relation to the basic electrical rhythm (BER) of the gut?

• A. SA node
• B. AV node
• C. Interstitial cells of Cajal
• D. Pyramidal cells

Hint:

The gut slow-wave pacemakers are mesenchymal cells near the myenteric plexus, not cardiac nodes.

Answer 1

The Correct Option is C

Step 1: The basic electrical rhythm (BER), or slow waves, is the spontaneous rhythmic oscillation of membrane potential in gastrointestinal smooth muscle, fluctuating between about -65 and -45 mV.

Step 2: These slow waves are generated by the interstitial cells of Cajal, the pacemaker cells of the gut. They are stellate mesenchymal cells with smooth-muscle-like features that lie between the muscle layers and near the myenteric plexus.

Step 3: The pacemaker frequency sets the maximal rate of contraction for each gut segment, in a descending gradient from stomach to small intestine, similar in concept to how the SA node sets cardiac rate. The SA and AV nodes, however, are cardiac, not gastrointestinal, and pyramidal cells are cortical neurons. Hence the gut pacemakers are the interstitial cells of Cajal.