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Structure and function of the heartAutonomic and hormonal control

In this Higher Human Biology revision guide, you will learn in detail that cardiac output is a measure of the rate of blood flow through the heart and its associated blood vessels. You can also revise the blood vessels leading into and out of the heart, the cardiac conduction system, and autonomic and hormonal control.

Part of Human BiologyPhysiology and Health

Autonomic and hormonal control

While the cardiac conduction system initiates each heartbeat, heart rate is not fixed. It can be altered by the activity of hormones and the nervous system.

The regulates the rate of the sino-atrial node through the antagonistic actions of the autonomic nervous system (ANS).

The autonomic nervous system comprises two antagonistic sets of nerves:

  • the sympathetic nerve pathway releases noradrenaline which increases heart rate
  • the parasympathetic pathway releases acetylcholine which decreases heart rate
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Cardiac conduction system

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