ENDOCRINE SYSTEM

• What is the endocrine system?

  A network of glands that manufacture and secrete chemical messengers - hormones, using blood vessels transfer messages to target sites within the body
• The system is controlled by the hypothalamus, and this acts as a thermostat for the body's hormones.
• • hormones are secreted when a gland is stimulated
  • this stimulation can be the result of a change in the concentration of a chemical or electrical impulses
  • hormones diffuse directly into the blood and bind to specific receptors for that hormone
  • the hormones then trigger a response in there target cells
• Pineal gland:


  Releases melatonin: is responsible for important biological rhythms, including the sleep wake cycle.
• Thyroid gland:


  Releases thyroxine: responsible for regulating metabolism.
• Hypothalamus:


  Stimulates and controls the release of hormones form the pituitary gland.
• Ovaries (female):


  Releases oestrogen: controls the regulation of the female reproductive system, including the menstrual cycle and pregnancy.
• Testes (male):

  Releases testosterone: responsible for the development of male sex characteristics during puberty while also promoting muscle growth.
• Adrenal gland (medulla):


  Releases adrenaline and noradrenaline: the key hormones in the fight or flight response.
• Adrenal gland (cortex):


  Releases cortisol: stimulates the release of glucose to provide the body with energy, while suppressing the immune system.