The endocrine system

• What does the endocrine system consist of?

  A network of glands that secrete hormones
• What are hormones?

  Chemical messengers that pass through the bloodstream
• How does thyroxine affect the body?

  It helps to regulate our metabolic rate
• Which gland secretes thyroxine?

  The thyroid gland
• What is the function of adrenaline?

  It causes our fight/flight response
• Which gland secretes adrenaline?

  The adrenal medulla
• What physiological changes does adrenaline cause?

  Increased heart rate, increased depth of breathing, dilation of pupils
• What does the pineal gland secrete?

  Melatonin
• How does melatonin affect the body?

  It helps regulate sleep and causes us to feel sleepy
• What are the key differences between the endocrine and nervous systems?

  • Hormones travel through the bloodstream; electrical messages travel via neurons
  • Endocrine responses take longer to take effect but last longer; nervous responses are immediate but short-lived