Endocrine System

• Glands - produce and secrete hormones
• Hormones - chemical substances that regulate the activity of cells and organs in the body
• Hormones

  • hormones excite/stimulate a particular part of the body
  • each hormone only affects its target cells
• The endocrine system is regulated by the hypothalamus.
• The hypothalamus signals a target gland to increase levels of a hormone - when sufficient levels are released, the hypothalamus shuts down.
• Pituitary Gland - 'master gland' that produces hormones which are sent into the blood stream and received by target cells.
• The pituitary gland is controlled by the hypothalamus.
• Adrenal glands - made up of 2 parts

  • adrenal cortex
  • adrenal medulla
• Adrenal cortex - releases hormones that are necessary for life

  • cortisol (stress response)
  • aldosterone (maintains blood volume and pressure)
• Adrenal medulla

  • noradrenaline (constricts blood vessels, BP increase)
  • adrenaline - increase HR and blood flow to muscles/brain
• Ovaries

  • responsible for the production of eggs, progesterone and oestrogen
• Testes

  • responsible for producing testosterone (controlled by hypothalamus and pituitary gland)