BRAINCAKENervous Control of the Heart
Heart rate is controlled by the cardiovascular control centre in the medulla oblongata. This centre receives information from receptors and sends impulses along two nerves of the autonomic nervous system to the sinoatrial node (SAN).
• The accelerator nerve is part of the sympathetic nervous system. Its neurones release noradrenaline at the SAN, which makes the SAN fire more often, so heart rate increases. Sympathetic neurones also supply the ventricle walls and increase the force of contraction, raising stroke volume.
• The vagus nerve is part of the parasympathetic nervous system. Its neurones release acetylcholine at the SAN, which makes the SAN fire less often, so heart rate decreases.
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All 41 lessons in Homeostasis · All Edexcel A-level Biology topics