Controlling the heart beat

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Controlling heart beat

  • Myogenic- intiate contractions
  • SAN acts as a pacemaker
  • Medulla Oblongata- nerves between heart and SAN

- accelerator nerve increases heart rate

- vagus nerve decreses heart rate

  • Adrenaline- directly effects heart by increasing its heart rate
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Exercise

  • Muscles need energy/ ATP to contract- increased respiration (need for more oxygen and glucose/fatty acids)
  • Heart increases cardiac output and stroke volume
  • More blood pumped to lungs and muscle
  • Increased carbon dioxide makes blood more acidic- detected by chemoreceptors in carotid artery and brain
  • Chemoreceptors send impulses to cardiovascular centre in the brain, leading to increased heart rate
  • Adrenaline acts directly on heart muscle by increasing heart rate
  • High blood pressure is detected by stretch receptors in carotid sinus
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