Physiology 3120 Lecture Notes - Lecture 2: Resting Potential, Sinoatrial Node, Membrane Potential

• School: Western University
• Department: Physiology
• Course: Physiology 3120
• Professor: Tom Stavraky

Document Summary

There are two types of action potentials found in the heart: Sa node action potential (slow response ap): has a slow rate of depolarization. The reason for the differences between the different ap"s is due to the different cells utilizing special ion channels to produce different currents which in turn produce distinctive action potentials. What is amazing is that both of these actions potentials can use the same channel in completely different ways. Some of the channels are voltage gated while others are ligand (chemically) gated and some are both ligand and voltage gated. Two major characteristics of the sa node, largely responsible for its self- excitability, are: As a result, the sa nodal cells do not have a stable resting membrane potential. Not like nerve cells that have a stable resting membrane potential of -70 mv (will stay at -70 mv until something excites it)