negative feedback

• What are hormones?

  Chemicals released directly into the bloodstream by glands
• Where are the adrenal glands located?

  At the top of the kidneys
• What hormone do the adrenal glands produce during times of fear or stress?


  Adrenaline
• What is one of the main effects of adrenaline?

  To increase the heart rate
• Why is increased heart rate important during stress?

  It delivers more oxygen and glucose to the brain and muscles
• What do oxygen and glucose provide for the body?

  They are needed for aerobic respiration
• What is the term scientists use to describe the body's response to fear or stress?

  Fight or flight
• Where is the thyroid gland located?

  At the base of the neck
• What hormone does the thyroid gland release?

  Thyroxine
• What are the two main effects of thyroxine?

  It stimulates the basal metabolic rate and plays a role in growth and development
• How is the level of thyroxine in the blood controlled?

  By negative feedback
• What monitors the level of thyroxine in the blood?

  The brain
• What happens when the thyroxine level falls?

  The pituitary gland releases TSH into the bloodstream
• What does TSH trigger the thyroid gland to do?

  Release more thyroxine into the blood
• What occurs when the thyroxine level increases?

  The brain prevents the pituitary gland from releasing TSH
• What is a negative feedback cycle?

  A process that triggers events to increase or decrease hormone levels
• What are the roles of thyroxine and adrenaline in the body?

  • Thyroxine stimulates basal metabolic rate and supports growth and development.
  • Adrenaline increases heart rate and prepares the body for fight or flight.
• What is the general idea behind negative feedback in hormone regulation?

  • Monitored by the brain.
  • Triggers hormone release when levels fall.
  • Prevents hormone release when levels rise.