PSL301H1 Lecture Notes - Lecture 28: Slow-Wave Potential, Esophagus, Migrating Motor Complex

• School: UTSG
• Department: Physiology
• Course: PSL301H1
• Professor: French, Gramolini, Richardson, Wong

Document Summary

The depolarization phase of the ap is the result of ca2+ entry into the cell. Contraction of smooth muscle is graded according to the amount of ca2+ that enters. In addition, this ca2+ entry initiates muscle contraction. Specialized smooth muscle cells have pacemaker activity: research indicate that slow waves originate in a network of cells called the interstitial cells of cajal (iccs, these modified smooth muscle cells lie between smooth muscle layers and nerve plexuses. Iccs function as pacemakers for slow wave activity in different regions of the gi tract. Pacemaker activity in the icc is not dependent on neural input, or hormonal input: but can be modulated by hormones and neurotransmitters, pacemaker activity is intrinsic to the icc. Things like hormones, parasympathetic innervation will actually depolarize the membrane, and make it easier for slow waves to produce ap. Sympathetic activation hyperpolarizes the membrane of the icc, making it more difficult to reach threshold.