controlling heart rate

• chemoreceptors


  • in carotid artery
  • aorta and brain detect pH levels in blood
  • during excersize, pH levels decrease due to CO2 in blood
  • chemoreceptors send action potentials to cardiovascular centre causing increase in heart rate
• stretch receptor (baroreceptors)


  • in carotid sinus
  • monitor blood pressure
  • if pressure increases, walls of carotid stretch - send action potentials to cardiovascular centre to reduce heart rate
• in medulla oblongata:

  • CAC cardio acceletory centre
  • CIC cardio inhibitory centre
• Accelerans (sympathetic)


  • CAC
  • noradrenaline
  • increases heart rate
• Vagus (parasympathetic)


  • CIC
  • acetylcholine
  • decreases heat rate
• action potentials send down the sympathetic nerve (accelerans) increases heart rate, whilst action potentials send down the parasympathetic nerve (vagus) reduces heart rate
• • when stretching or during muscle contraction, sensory endings change shape which causes an action potential
  • sends info to cardiovascular system which leads to an increase in heart rate - extra oxygen will soon be needed