The Endocrine System

• Hormones

  chemical molecules that are released directly into the blood
• Hormones are carried in the blood to other parts of the body but only affect particular cells in particular organs (called target organs)
• Hormones control things in organs that need constant adjustment
• Hormones are produced in and secreted by various glands, called endocrine glands
• Endocrine glands make up the endocrine system
• Hormones tend to have relatively long-lasting effects
• Pituitary gland:

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

  • found in the neck
  • produces thyroxine
  • involved in regulating things like rate of metabolism, heart rate and temperature
• Ovaries (female only):

  • produce oestrogen
  • involved in the menstrual cycle
• Testes (male only):

  • produce testosterone
  • controls puberty and sperm production in males
• Adrenal gland:

  • found on the kidneys
  • produces adrenaline
  • prepares the body for a 'fight or flight' response
• Pancreas:

  • produces insulin
  • regulates the blood-glucose level