Negative Feedback

• What should you be able to explain by the end of the video on thyroxine and adrenaline?


  You should be able to explain the roles of thyroxine and adrenaline in the body.
• What is the role of hormones in the body?

  Hormones are chemicals released directly into the bloodstream by glands that cause effects in specific target organs.
• Where are the adrenal glands located?


  The adrenal glands are located at the top of the kidneys.
• What hormone do the adrenal glands produce during times of fear or stress?


  The adrenal glands produce the hormone adrenaline during times of fear or stress.
• What is one of the main effects of adrenaline in the body?


  One of the main effects of adrenaline is to increase the heart rate.
• Why does an increased heart rate benefit the body during stress?


  It delivers more oxygen and glucose to the brain and muscles, which are needed for aerobic respiration.
• What is the term used to describe the body's response to fear or stress?

  Scientists call this response the fight or flight response.
• Where is the thyroid gland located?


  The thyroid gland is found in the base of the neck.
• What hormone does the thyroid gland release?


  The thyroid gland releases the hormone thyroxine.
• What are the two main effects of thyroxine in the body?


  Thyroxine stimulates the body's basal metabolic rate and plays an important role in growth and development.
• How is the level of thyroxine in the blood controlled?


  The level of thyroxine in the blood is controlled by negative feedback.
• What happens when the thyroxine level falls in the blood?


  The pituitary gland releases the hormone TSH into the bloodstream.
• What does TSH trigger in the body?


  TSH triggers the thyroid gland to release more thyroxine into the blood.
• What occurs when the thyroxine level increases in the blood?


  The increased level of thyroxine is detected by the brain, preventing the pituitary gland from releasing TSH.
• What is a negative feedback cycle?


  A negative feedback cycle is a process where an increase in a substance triggers events that decrease its level, and vice versa.
• What are examples of negative feedback cycles in the human body?


  • Control of blood glucose
  • Menstrual cycle
• Where can students find questions on the adrenal glands, thyroid gland, and negative feedback?


  Students can find questions in the vision workbook linked in the video.