Negative feedback

• What should you be able to explain by the end of the video?

  The roles of thyroxine and adrenaline
• What is the endocrine system responsible for?

  Releasing hormones directly into the bloodstream
• Where are the adrenal glands located?

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

  Adrenaline
• What is one main effect of adrenaline?

  Increases heart rate
• Why does adrenaline increase heart rate?

  To deliver more oxygen and glucose
• What do oxygen and glucose provide for the body?

  Needed for aerobic respiration
• What is the term used for 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?

  Stimulates metabolic rate and growth
• What does metabolism refer to?

  The sum of all reactions in a cell
• How is thyroxine level controlled?

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

  The brain
• What does the pituitary gland release when thyroxine levels fall?

  TSH (Thyroid Stimulating Hormone)
• What does TSH trigger the thyroid gland to do?

  Release more thyroxine
• What happens when thyroxine levels increase?

  Prevents the pituitary gland from releasing TSH
• What is a negative feedback cycle?

  Events triggered to maintain balance
• Can you name other negative feedback cycles in the body?

  Blood glucose control and menstrual cycle
• What are the roles of thyroxine and adrenaline in the body?

  • Thyroxine:
  • Stimulates metabolic rate
  • Aids in growth and development
  • Adrenaline:
  • Increases heart rate
  • Prepares body for fight or flight
• What is the general idea behind negative feedback?

  • Monitors hormone levels
  • Triggers responses to maintain balance
  • Prevents overproduction or underproduction of hormones
• What should students focus on for exam preparation regarding this topic?

  • Adrenal glands
  • Thyroid gland
  • Negative feedback mechanisms