Control of Heart Rate
The reason the SA node controls the whole
heart acting as the natural pacemaker, is that its action potentials
are released most often, this triggers other cells to generate their
own action potentials. In the muscle cells, this will produce contraction.
The action potential generated by the SA node,
passes down the cardiac conduction system, and arrives before the
other cells have had a chance to generate their own spontaneous
action potential. This is the normal conduction of electrical activity
within the heart.
Control of heart rate
The heart gets its Parasympathetic nervous system
innervations from the vagus nerve. Signals from this nerve cause
the heart rate to decrease. Sympathetic stimulation comes from the
cardiac nerves. Activity in these nerves acts to increase heart
rate.
Devices with pacemaker function
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Heart
