Contol Of Heart Rate Flashcards

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0
Q

Explain the hormonal response

A
  • adrenaline is secreted in response to stress, shock etc
  • presence of adrenaline in the blood increases heart rate
  • prepares body for activity
  • action of adrenaline (cyclic AMP)
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1
Q

Explain how heart rate is controlled

A

• SAN –> sends a wave of excitation across the the atria which causes them to contract
• non conductive collagen fibres block transmission of wave of excitation into ventricles
• Impulse is delayed at the AVN (allows ventricles to empty)
• AVN –> sends impulse down purkyne fibres to apex of the heart
–> impulse spreads out over ventricles from the apex up, ventricles contact from the apex up

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2
Q

What happens to heart rate when the body is experiencing high blood pressure?

A
  • baroreceptors in the aorta and vena cava detect high blood pressure
  • impulses are sent to cardiovascular centre of the medulla
  • this causes an impulse to be sent along the vagus nerve
  • this causes acetylcholine to be secreted which bind to receptors on the SAN
  • this causes heart rate to slow down to reduce the blood pressure back to normal
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3
Q

What happens to heart rate when the body is experiencing low blood pressure?

A
  • baroreceptors in the aorta and vena cava detect low blood pressure
  • impulses are sent to cardiovascular centre of the medulla
  • this causes an impulse to be sent along the accelerator nerve
  • this causes noradrenaline to be secreted which binds to receptors on the SAN
  • this causes heart rate to speed up to increase the blood pressure back to normal
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4
Q

What happens to heart rate when the body is experiencing high blood O2, low co2 or high pH levels?

A
  • chemoreceptors in the aorta and carotid artery detect chemical changes in the blood
  • impulses are sent to cardiovascular centre of the medulla
  • this causes an impulse to be sent along the vagus nerve
  • this causes acetylcholine to be secreted which binds to receptors on the SAN
  • this causes heart rate to decrease to return O2, co2 and pH levels back to normal
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4
Q

What happens to heart rate when the body is experiencing low blood O2, high co2 or low pH levels?

A
  • chemoreceptors in the aorta and carotid artery detect chemical changes in the blood
  • impulses are sent to cardiovascular centre of the medulla
  • this causes an impulse to be sent along the accelerator nerve
  • this causes noradrenaline to be secreted which binds to receptors on the SAN
  • this causes heart rate to increase to return O2, co2 and pH levels back to normal
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