Controlling heart rate

• The medulla oblongata is responsible for controlling heart rate.
• There are two centres within the medulla oblongata, linked to the SAN. One centre increases heart rate by sending impulses through the sympathetic nervous system (impulses are transmitted by the accelerator nerve). The other centre decreases heart rate by sending impulses through the parasympathetic nervous system (impulses are transmitted by the vagus nerve).
• Baroreceptors = detect changes in blood pressure
• Chemoreceptors = detect changes in pH of blood
• Control of heart rate:

  • increased metabolic/muscular activity
  • more carbon dioxide produced from respiration
  • blood pH is lowered
  • centre in the medulla oblongata responsible for increasing heart rate increases frequency of impulses to SAN via the sympathetic nervous system
  • SAN increases heart rate
  • increased blood flow removes carbon dioxide faster