Adrenaline and Thyroxine

• Adrenaline

  A hormone released by the adrenal glands in response to stressful or scary situations
• Adrenaline's function

  • Prepares the body for "fight or flight"
  • Increases supply of glucose and oxygen to cells in the brain and muscles
• Adrenaline is released by the adrenal glands which are just above the kidneys
• Negative feedback


  A mechanism that controls hormone levels in the blood by bringing them back to normal
• Thyroxine

  A hormone released by the thyroid gland that regulates metabolism
• Thyroxine's function

  • Regulates the basal metabolic rate
  • Stimulates protein synthesis for growth and development
• Thyroxine is released in response to thyroid-stimulating hormone (TSH), which is released from the pituitary gland
• When the level of thyroxine in the blood is higher than normal


  The secretion of TSH from the pituitary gland is inhibited
• Inhibition of TSH secretion


  Reduces the amount of thyroxine released from the thyroid gland
• When thyroxine levels fall back towards normal

  TSH is released again
• Thyroxine is made from iodine and amino acids
• Thyroxine plays an important role in regulating the basal metabolic rate
• Thyroxine is important for various processes in the body