The Endocrine System

• Endocrine system:

  • The endocrine system is a network of glands throughout the body
  • These glands secrete hormones into the bloodstream which are sent to target cells and organs
• The Endocrine system:

  • The endocrine system helps to regulate the activity of cells and organs in the body, and controls vital physiological processes in the body
  • Endocrine system works differently to the nervous system: it doesn’t use nerves to transmit information and instead uses blood vessels to deliver hormones to their target sites in the body.
• Glands:

  - Glands are organs in the body that produce hormones
• Hormones

  • Chemicals that circulate in the bloodstream and are carried to target sites throughout the body.
  • Each hormone stimulates a particular part of the body.
  • Too much or too little of a particular hormone can result in dysfunction of bodily systems.
  • E.g. If cortisol levels are too high this can lead to depression and high blood pressure.
• Pituitary gland:

  • The ‘master gland’, located in the brain
  • It controls the release of hormones from ALL other endocrine glands in the body.
  • It produces hormones (e.g. ACTH) which then stimulate the release of hormones from other glands. 
  • It is controlled by the hypothalamus which receives info about functions of the body and then uses this to regulate them
• Adrenal glands

  2 : Adrenal Cortex and Adrenal Medulla
• Adrenal cortex

  • Produces the hormone cortisol
  • Regulates/supports a variety of bodily functions (e.g. cardiovascular and anti-inflammatory functions)
  • Cortisol production increases in response to stress. (long-term stress). Helps us deal with stress
  • Low cortisol levels lead to low blood pressure, poor immune system and inability to deal with stress.
• Adrenal Medulla:

  • Releases adrenaline and noradrenaline
  • These hormones prepare body for fight or flight (short-term stress)
  • Adrenaline helps us respond to short-term/immediate stressful situation 
  • e.g. increasing heart rate 🡪  increase blood flow to muscles and brain 🡪 convert glycogen to glucose for energy