Heart rate regulation

• What is the role of the sympathetic nervous system during exercise?


  It stimulates the SA node to increase heart rate.
• Why do muscles require greater volumes of oxygen during exercise?


  Because they are working harder and need more energy.
• What happens to the heart rate after exercise is finished?

  The parasympathetic nervous system reduces stimulation of the SA node, lowering heart rate.
• What is the function of the parasympathetic nervous system after exercise?


  It acts to reduce heart rate and return it to resting levels.
• Where is the cardiac control center located?


  In the medulla oblongata of the brain.
• What does the cardiac control center do during exercise?


  It receives information from receptors about changes in the body and sends impulses to increase heart rate.
• What nerve does the cardiac control center use to increase heart rate?


  The accelerator nerve.
• How does the sympathetic nervous system increase heart rate?


  By sending impulses down the accelerator nerve to increase the firing rate of the SA node.
• What is the effect of increased heart rate on oxygen delivery to muscles?


  It allows more oxygen to be delivered to the working muscles.
• What are the roles of the sympathetic and parasympathetic nervous systems in heart rate regulation?

  • Sympathetic nervous system:
  • Increases heart rate during exercise
  • Stimulates SA node via accelerator nerve
  • Parasympathetic nervous system:
  • Decreases heart rate after exercise
  • Reduces stimulation of SA node
• What is the primary function of the parasympathetic nervous system?


  To reduce heart rate
• Where is the cardiac control centre located?


  In the medulla oblongata of the brain
• What type of information does the cardiac control centre receive?


  Information from receptors about changes in the body
• What happens to the heart rate when exercise ceases?


  The heart rate decreases
• Which nerve does the cardiac control centre use to decrease heart rate?

  The vagus nerve
• What is the effect of decreased firing rate of the SA node?


  It decreases heart rate
• What is the consequence of a decreased heart rate on oxygen delivery?


  Less oxygen is delivered to the working muscles
• What hormones are released from the adrenal gland in response to exercise?


  Adrenalin and nor-adrenalin
• How do adrenalin and nor-adrenalin affect the heart muscle?


  They increase the force of contraction
• What is the effect of increased force of contraction on stroke volume?

  It increases stroke volume
• What happens to heart rate as a result of increased firing rate of the SA node?


  Heart rate increases
• What is the combined effect of increased stroke volume and heart rate on cardiac output?


  It increases cardiac output
• What is the role of cardiac output in relation to working muscles?


  It increases the delivery of oxygenated blood to the working muscles
• What are the intrinsic controls of heart rate regulation during exercise?


  • Temperature: Rises during exercise, increasing speed of nerve impulses
  • Venous Return: Increases heart rate, which increases end-diastolic volume (EDV) and therefore increases stroke volume (SV)
  • Opposite effects occur after exercise
• What happens to temperature during exercise?


  It rises
• How does increased venous return affect heart rate?


  It increases heart rate
• What is the relationship between end-diastolic volume (EDV) and stroke volume (SV)?


  Increased EDV leads to increased SV
• What happens to heart rate and stroke volume after exercise?


  They both decrease
• What is venous return?


  It is the return of blood to the heart through the venules and veins back to the right atrium.
• How does venous return change during exercise?


  It increases to meet the greater demand for oxygenated blood, enhancing stroke volume and cardiac output.
• What does Starling's Law state?


  It states that the greater the venous return, the greater the stroke volume.
• What happens to the ventricles as venous return increases?


  The walls of the ventricles are stretched further, resulting in a more powerful contraction.
• What does the term MYOGENIC refer to?


  It refers to the capacity of the heart to generate its own electrical impulse.
• What is the result of the heart generating its own electrical impulse?


  It causes the cardiac muscle to contract.