Heart rate regulation

• Cardiac control centre


  Located in the medula oblongata (in brain), responsibie for regulatin our heart rate
• Sympathetic Nervous System (SNS)


  Stimulated to increase heart rate , by increasing firing rate of SA node, via the accelerator nerve
• Parasympathetic nervous system (PNS)

  Stimulated to slow down heart rate, by decreasing firing rate of the SA node, via the Vagus nerve
• Hormonal control of heart rate

  Adrenaline is secreted by the adrenal glands, stimulates the SNS, increasing firing rate of the SA node, therefore increasing HR, SV and Q
• Chemoreceptors


  Detect an increase/decrease in CO2 and a decrease/increase in O2
• Proprioreceptors


  Located in the muscles, tendons and joints, detect an increase or decrease in joint movement
• Baroreceptors


  Located in blood vessel walls, detect an increase or decrease in blood pressure
• Neural control of heart rate during exercise

  All receptors (C,P,B) inform the Cardiac Control centre controlled by the autonomic nervous system...

  ...To stimulate the sympathetic Nervous system, via the accelerator nerve...

  ...Increasing firing rate of SA node...

  ...Increasing HR,SV and Q
• Neural control during recovery

  Stimulates parasympathetic nervous system via vagus nerve

  Decreasing firing rate of SA node

  Decreasing HR, SV and Q
• Temperature (intrinsic control)


  - increased temperature, increases speed of nerve transmission , increasing firing rate of SA node, therefore increasing HR, SV and Q
• Venous return


  The amount of blood returned to the heart by the veins
• Venous return (intrinsic control)

  Increases Venous return, so more blood returned to back of the Right Atria, increasing firing rate of SA node ,therefore increasing HR

  More blood forced into the ventricles, so increased ventricular stretch (FOC), therefore increasing SV, Q
• Starling's Law


  The more the heart is filled during diastole the more forcefully it contracts