endocrine system

• • is a network of glands (special group of cells)
  • distributed around the body; manufacture and secrete chemical messengers called hormones which travel through the bloodstream
  • works closely with the nervous system to regulate physiological processes
  • blood vessels deliver hormones to target sites around the body
• • hormones regulate activity of cells and organs; each gland produces different hormones; a given hormone usually only affects a limited umber of cells called target cells which have receptors for that hormone.
• pituitary gland (''master gland'')

  • influences the release of hormones from other glands
  • controlled by hypothalamus which recieves info about basic functions of the body then use this info to regulate these functions
• pituiatry gland (2)

  • PG releases hormones that travel through bloodstream to their target and either enter directly cayse a change in physiological processes or stimulate other glands to produce hormones
  • high levels of hormones can stop the hypothalamus and pituitary gland, releasing more of their hormones; this negative feedback prevents hormone levels becoming too high
• anterior and prosterior - pituiatry gland (3)

  • the anterior and prosterior release different hormones
  • eg, anterior releases ACTH in response to stress as it stimulates adrenal glands to release cortisol; the anterior also releases hormones that stimulate the brain to produce oestrogen + progestrone (LH + FSH);
  • the prosterior releases oxytocin which stimulates contraction of the uterus during childbirth and is important for bonding
• adrenal glands

  • located on top of kidneys
  • each gland has 2 parts
  • outer part is called the adrenal cortex
  • inner region is callede the adrenal medulla
  • hormones release by adrenal cortex are necessary for life whereas those released by the adrenal medulla are not
  • adrenal cortex release cortisol which regulatesa number of functions including cardiovascular and anti-inflammatory functions;
  • the adrenal medulla releases adrenaline + noradrenaline (increasing heart rate and blood flow, increasing BP)