The pacemaker potential of the SA node cells results from the slow inflow of

Name: Problem 14, Chapter 19: Anatomy and Physiology
Uploaded: 2020-06-10T00:48:10-08:00
Duration: 2 min 21 s
Channel: Zachary Papazian
Description: The pacemaker potential of the SA node cells results from the slow inflow of

step 1 Probably all heard of pacemakers and may even know someone who has a pacemaker. And what pacemak

The pacemaker potential of the SA node cells results from...

Key Concepts

Pacemaker Potential

This refers to the gradual and spontaneous depolarization of cardiac pacemaker cells that occurs during diastole, leading up to each action potential. It is the underlying mechanism that enables the heart's rhythmic contraction, as the membrane potential slowly moves toward the threshold required to trigger an action potential.

Automaticity

Automaticity is the intrinsic ability of certain cells, such as those in the SA node of the heart, to depolarize and generate action potentials without external stimuli. This self-initiating property is essential for the regular and rhythmic beating of the heart.

Ion Channel Dynamics

The generation of the pacemaker potential involves a coordinated action of various ion channels whose permeabilities change over time. The slow inward movement of ions, such as sodium through specific channels, initiates the slow depolarization phase, while subsequent activation of calcium channels further contributes to the threshold attainment for an action potential.

Hyperpolarization-activated (Funny) Channels

Often referred to as funny channels, these hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are critical in pacemaker cells. They gradually allow the influx of positive ions, primarily sodium, after hyperpolarization, contributing significantly to the slow, spontaneous depolarization phase that characterizes the pacemaker potential.

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