Mechanism?
The cardiac muscle is myogenic.
The heart beat starts at sinoatrial node/pacemaker.
The impulse from the pacemaker spread across both atria.
Both atria contract.
The impulse reach atrioventricular node.
Impulse travel through bundle of His to purkinje tissues/purkyne tissues.
And then spread to all parts of both ventricles.
Both ventricles contract/ventricular systole.
Control?
Cardiovascular centre is located in the medulla oblongata.
The heart is supplied by two nerves : vagus/parasympathetic and sympathetic nerves.
Impulse from cardiac inhibitory centre is transmitted to sinoatrial node through vagus nerve.
Vagus/parasympathetic nerve slows down the rate of heart beat.
Impulse from cardiac acceleratory transmitted to sinoatrial node through sympathetic nerves.
Sympathetic nerves increase/speed up the rate of heart beat.
Adrenaline/Epinepherine/Thyroxine also increases/speeds up the rate of heart beat.
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