heart excersise and control

• Vascular system


  Circulates blood in vessels
• How is cardiac output calculated?

  Cardiac output is calculated by multiplying the heart rate (number of heartbeats per minute) by the stroke volume (volume of blood pumped by the heart with each beat).

  HR x SV = CO
• Cardiac centre names in the medulla

  • Cardioacceleratory centre
  • Cardioinhibitory centre
• Control of Heart Ratein the brain

  1. BRAIN

  2. MEDULLA Cardiac Centre

  3. NERVE IMPULSE VIA THE SYMPATHETIC NERVOUS SYSTEM (NORADRENALINE) involved in "fight or flight"

  4. NERVE IMPULSE VIA THE PARASYMPATHETIC NERVOUS SYSTEM (ACETYLCHOLINE) involved in "rest and digest"
• how is heart rate increase controlled by the brain?

  1. increased by cardio acceleratory centre
  2. impulse sent along sympathetic neurons to the SAN
  3. noradrenaline is released to stimulate SAN
• how is heart rate decrease controlled by the brain?

  1. decreased by cardio inhibitory centre
  2. impulses sent along parasympathetic neurons to the SAN
  3. acetylcholine is released to inhibit SAN
• How is heart rate effected by exercise?

  1. CO2 dissolves in the blood to produce carbonic blood. This lowers the pH
  2. Chemoreceptors in the medulla and aortic + caortic bodies are stimulated
  3. These transmit impulses to:

  • Respiratory centres in Medulla, to increase ventillation
  • Cardiac centres in Medulla, to increase heart rate
  • In the cardiac centre: more impulses from sympathetic neurones from cardio acceleratory centre to the SAN
• how is heart rate returned to normal when exercise was complete?

  • CO2 is reduced in the blood
  • less impulses are transmitted to chemoreceptors in the Medulla
• What is venous return in exercise?

  Its when the muscles during exercise contract more strongly

  this causes pressing on veins

  this increases the rate at which the blood returns to the heart

  therefore this causes cardiac muscles to contract strongly too, so higher stroke volume
• How is blood pressure regulated during exercise?

  • its detected by pressure receptors of aorta and the cartoid artery
  • if increases too much, impulses from receptors -> cardio inhibitory centre
  • impulses travel from parasympathetic neurons -> SAN
  • heart rate is decreased and blood pressurse is reduced