.6 feedback system

• Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.
• Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development.
• Thyroxine levels are controlled by negative feedback.