Endocrine System

• Endocrine system


  A network of glands throughout the body whose main function is to control or regulate the activity of particular cells or organs in the body
• Function of the endocrine system

  1. Glands secrete hormones directly into the bloodstream or circulatory system

  2. Hormones released by these glands are vital to most of the physiological functions of the body
• Pituitary gland


  The 'master gland' - rather than having a direct effect on tissues of the body, the function of this gland is to control other endocrine glands
• Hypothalamus


  Controls the release of hormones from the pituitary gland, and is thus considered to have general control of the endocrine system
• Other key glands, hormones and functions

  • Thyroid, releases thyroxine, function - regulates metabolic rate
  • Testes, release androgens, function - development of male characteristics at puberty
  • Ovaries, release oestrogens, function - regulate female reproductive system
  • Pineal, releases melatonin, function - regulates biological rhythms
  • Adrenal medulla, releases adrenaline and noradrenaline, function - fight or flight response
  • Adrenal cortex, (i) releases glucocorticoids eg cortisone, function - release glucose, suppress immune response, (ii) releases mineral corticoids, function - regulates water balance of the body
• Endocrine glands


  • To produce/secrete hormones into the bloodstream
  • To monitor/control/regulate the body's internal environment/organs/cells
  • To initiate changes in body function, eg initiate the fight and flight response by releasing adrenaline
• Endocrine system


  • The main function is to control or regulate the activity of particular cells or organs (internal physiological regulations)
  • Glands secrete hormones directly into the bloodstream
  • Hormones released by these glands are vital to most of the physiological functions of the body
  • The hypothalamus controls the endocrine system through the pituitary gland
  • The pituitary gland controls other endocrine glands
• Function of the endocrine system

  1. Release hormones/chemical messengers from glands into the bloodstream

  2. Hormones bind with specific receptors

  3. Regulate the activity of cells or organs in the body
• Specific hormones


  • Adrenaline and fight or flight response
• Imbalance in hormones


  May lead to dysfunction, for example, high levels of cortisol causing Cushing's disease