The endocrine system

• what is the endocrine system?

  Network of glands in the body that manufacture and secrete chemical messengers (hormones). Main function is to maintain homeostasis.
• Nervous system vs endocrine system

  •Separate from the nervous system but work together

  •Main difference: NS transmits information through nerves, the endocrine system uses the bloodstream to deliver hormones to target sites in the body

  •NS has instant response, but the endocrine system is slightly delayed and longer lasting
• Pituitary gland

  •Produces hormones – main function is to influence the release of hormones from other glands, regulating body functions.

  •Controlled by the hypothalamus (just above pituitary gland in brain).

  •The pituitary gland produces hormones that travel in the bloodstream to their specific target. 
• Adrenal cortex

  •The adrenal cortex produces cortisol which regulates many important bodily functions

  •E.g. cardiovascular and anti-inflammatory.

  •Cortisol production is increased in response to stress.

  •If the cortisol level is low, the individual has low blood pressure, poor immune function and an inability to deal with stress.
• adrenal medulla

  •The adrenal medulla releases adrenaline and noradrenaline that prepare the body for fight or flight.

  •Adrenaline increases heart rate and blood flow to the muscles and brain.

  •Noradrenaline constricts blood vessels, causing blood pressure to increase.
• Ovaries

  -Part of the female reproductive system

  -Progesterone has been associated with heightened sensitivity to social cues
• Testes


  Male reproductive glands that produce testosterone. Testosterone causes development of facial hair, deepening of the voice & growth spurt, plays a role in sex drive, sperm production & maintenance of muscle strength Testosterone not exclusively male hormone, women have testosterone in smaller amounts
• Glands and hormones

  • maintains homeostasis in our body
  • regulated by feedback
  • signal sent from hypothalamus to pituitary gland in the form of a releasing hormone
  • causes pituitary to secrete a simulating hormone
  • as levels of the hormone increase, hypothalamus stops secreting of the releasing hormone and pituitary stops secreting the stimulating hormone
• Thyroid

  -The thyroid gland produces the hormone thyroxine

  -This hormone affects the cells in the heart (increases heart rate)

  -Also affects cells throughout the body increasing metabolic rates (chemical processes taking place in cells)

  -This turns into growth rates
• fight or flight

  •When a stressor is perceived by the brain the hypothalamus triggers the ANS

  •Changes from its normal resting state (parasympathetic) to its sympathetic state

  •The pituitary gland releases ACTH (adrenocorticotrophic hormone)

  •This causes the adrenal glands to release adrenaline in the bloodstream leading to physical changes (e.g. increased heart rate)

  •When the stressful event/threat is over the parasympathetic nervous system kicks in and slows the heart rate amongst other things (rest and digest response)