A-LEVEL BIOLOGY AQA NOTES
control of heart rate
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Control of the Heart Rate
- Cardiac muscle is myogenic, meaning it can contract and relax without receiving signals from the nervous system
- The sinoatrial node (SAN) sends out regular waves of electrical activity to the left & right atrial wall causing contraction. The electrical waves are then passed onto the atrioventricular node (AVN), then to the bundle of His, with a slight delay. The bundle of His splits into the Purkynge tissue, causing contraction of the left & right ventricles from the bottom up.
- The rate at which the SAN fires is controlled unconsciously by the medulla oblongata in the autonomic nervous system