Negative feedback

• What is negative feedback?

  type of control where the body responds to an increase or decrease in a factor by returning it to the optimum level
• What is thyroxine?

  • hormone released by thyroid gland
  • release is triggered by the thyroid stimulating hormone (TSH)
  • controls the body’s metabolic rate, growth and development
• How is the release of thyroxine controlled by negative feedback?

  • levels of blood thyroxine falls - detected by receptors in the brain
  • pituitary gland releases more TSH
  • more thyroxine produced and released by the thyroid gland
  • blood thyroxine level returns to normal
• What are the effects of adrenaline?

  • increase in H&BR - delivers oxygen and glucose to the body
  • stored glycogen converted to glucose
  • dilation of pupils
  • increased mental awareness
  • blood diverted away from digestive system to muscles