Heartbeat

Question 1

control of heartbeat

Answer 1

• SA node on the wall of the right atrium
  creates an electrical excitation
• excitation spreads over both atria so both
  contract together
• excitation spreads to the ventricles
  through the AV node
• AV node creates a delay to allow atria to
  empty and contract
• AV node passes the excitation down the
  bundle of his to the apex of the heart
• excitation is transmitted to the purkinje
  fibres within the ventricle wall
• excitation is carried upwards through the
  ventricle wall causing cardiac muscle to
  contract
• pushing blood to the aorta and
  pulmonary artery, and empties the
  ventricles

Question 2

ECG’s

Answer 2

P wave -
- shows the voltage change generated by
the SA node
PR interval -
- time taken for the excitation to spread
from atria to ventricle through AV node
QRS -
- shows the contraction of the ventricle
T wave -
- shows the relaxation of the ventricle