Feedback systems

• Adrenaline

  • Produced by adrenal glands in times of fear/stress
  • Targets vital organs, increases heart rate and delivery of oxygen and glucose to brain and muscles
  • Converts glycogen to glucose so more energy released in the muscles
  • Diverts blood away from digestive system to muscles
• Explain how the effect of adrenaline on heart rate might cause reaction time to decrease (4)

  • Adrenaline increases heart rate
  • Which increases oxygen and glucose to brain
  • Which increases rate of respiration
  • So releasing more energy for faster muscle contraction
• Role of Thyroxine

  • Produced from Thyroid and stimulates Basal Metabolic Rate
  • It plays an important role in growth and development
• Thyroxine negative feedback (4-6)

  • LEVELS ARE TOO LOW:
  • Pituitary Gland releases TSH which stimulates thyroid gland to release more thyroxine
  • Levels go up to normal
  • LEVELS ARE TOO HIGH:
  • Thyroxine inhibits release of TSH
  • This means less Thyroxine released
  • So levels fall back to normal