Control of Heart Rate

Mind map showing the way in which heart rate is controlled in humans including the way in which the heart itself is adapted for it's function and the different parts of the body that contribute to the control of heart rate

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  • Control of heart rate
    • Adaptations to supply more O2 and glucose
      • Increase the stoke volume or the volume of blood pumped per beat
    • How heart rate is controlled
      • Heart is made of myogenic tissue
      • Sinoatrial node acts as a pacemaker for the heart
        • Able to initiate an action potential causing the heart to contract
        • Found at top of the heart above the atria
        • Has a set frequency of between 60-80bpm
      • Nerves from the medulla oblongata in the brain
        • Affect the frequency of contractions by passing action potentials down the accelerator or vagus nerves
      • Heart rate increases when the adrenaline is present in the blood
    • Factors that affect heart rate
      • Controlled by the cardiovascular centre in medulla oblongata
      • Limb movement is detected by stretch receptors in muscles
        • Sends messages to the cardiovascular centre that more oxygen is required
          • Detected by chemoreceptors in the carotid arteries
      • Increased carbon dioxide in the blood after exercise reduces the pH of the blood
        • Detected by chemoreceptors in the carotid arteries
        • When carbon dioxide levels fall after exercise accelerator nerve activity decreases slowing the heart rate
      • Adrenaline released in response to stress, shock or excitement increasing the heart rate
      • If blood pressure rises too high the heart rate is reduced
        • Detected by stretch receptors in the carotid sinus, a small swelling in the carotid artery


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