Endocrine system

• The endocrine system


  A network of glands that produce and secrete into the bloodstream chemical messengers known as hormones - which are then transported towards target cells in the body, with complementary receptors.

  
  

  It works in conjunction with the nervous system to ensure essential physiological processes and important behaviours take place - like metabolism, growth, sexual development.

  
  

  The hypothalamus in the brain links the nervous system to the endocrine system via the pituitary gland.
• Hormones


  Hormones are the body's chemical messengers.

  
  

  They travel through the bloodstream, influencing different processes like mood, the stress response etc...
• Pituitary Gland - hormone?

  Many hormones including ACTH, TSH (thyroid-stimulating hormone), LH and FSH.
• Pituitary Gland - function?

  Releases hormones which control and stimulate the release of hormones from other glands in the endocrine system.

  
  

  For example, ACTH triggers the adrenal gland to release stress hormones.
• Pineal Gland - hormone?


  Melatonin
• Melatonin - function?

  regulates sleep/wake cycle (circadian rhythm)

  is released when there is a lack of light to promote feelings of sleepiness.
• Thyroid Gland - hormone?

  Thyroxine
• Thyroxine - function?

  Regulates the body's metabolic rate - controlling heart, muscle and digestive function, brain development and bone maintenance.

  
  

  Metabolism is involved in the chemical process of converting food to energy.
• Adrenal glands - hormone?

  Cortisol - released from the adrenal cortex (the outside of the gland)

  Adrenaline and noradrenaline - released from the adrenal medulla (the middle of the gland)
• Cortisol - function?


  Increases blood glucose levels and diverts the glucose to the muscles by suppressing systems deemed less important in that present moment (this includes the immune system) - to provide energy to fuel the fight or flight response.
• Adrenaline - function?


  Increases heart rate and respiration to increased the rate of blood flow to and from the muscles for fight or flight.
• Pancreas - hormone?


  Insulin
• Insulin - function?


  Regulates blood glucose levels through the metabolism of carbohydrates, fats and proteins by promoting the absorption of glucose from the blood into liver, fat and skeletal muscle cells.
• Ovaries - hormones?


  Oestrogen and Progesterone
• Oestrogen and Progesterone - function?

  Both hormones work together to regulate the menstrual cycle.

  
  

  oestrogen = repairs and thickens uterus lining to prepare it for pregnancy

  progesterone = maintains uterus lining ready for the implantation of a fertilised egg

  
  

  They both inhibit LH so only one egg is released per menstrual cycle
• Testes - hormone?


  Testosterone
• Testosterone - function?


  Sperm development.

  Higher levels associated with periods of sexual activity.

  Increased levels have also been linked to aggression.