The Endocrine System

• Hormones


  Chemical messengers sent in the blood
• How hormones work


  1. Hormones are released directly into the blood

  2. They are carried in the blood to other parts of the body

  3. They only affect particular cells in particular organs (called target organs)

  4. Hormones control things in organs and cells that need constant adjustment

  5. Hormones are produced in and secreted by various glands, called endocrine glands
• Hormones


  • They tend to have relatively long-lasting effects
• Endocrine system


  The system of glands that make up the endocrine system
• Pituitary gland


  • It produces many hormones that regulate body conditions
  • It is sometimes called the 'master gland' because these hormones act on other glands, directing them to release hormones that bring about change
• Thyroid


  • It produces thyroxine which is involved in regulating things like the rate of metabolism, heart rate and temperature
• Ovaries (females only)


  • They produce oestrogen, which is involved in the menstrual cycle
• Adrenal gland


  • It produces adrenaline which is used to prepare the body for a 'fight or flight' response
• Testes (males only)


  • They produce testosterone, which controls puberty and sperm production in males
• Pancreas


  • It produces insulin which is used to regulate the blood glucose level