2. The endocrine system

• Glands


  An organ in the body that synthesises hormones and secretes them
• Thyroid gland


  • Neck, secretes thyroxine, controls the rate of metabolic reactions and increases heart rate
• Adrenal gland


  • On top of each kidney, secretes adrenaline, responsible for our fight or flight responses
• Testes


  • Scrotum, secretes testosterone in men, allows for male development - growing body hair, deepening of voice and maturation of muscles
• Pituitary gland


  • Brain, 'master gland', controls the release of hormones from all other endocrine glands in the body
• Fight or flight response


  The body's way of preparing. Becoming ready to fight an aggressor or flee
• Adrenaline


  Released by adrenal glands and a part of the body's immediate stress response
• What happens after the fight or flight response?

  • Once threat has passed, parasympathetic nervous system returns the body to normal resting state
• Parasympathetic and sympathetic nervous systems

  Work in opposite - antagonistic
• The endocrine system

  • One of the body's major information systems
  • Works alongside the nervous system to control vital function in the body. 
  • Instructs glands to release hormones directly into the bloodstream  
  • Hormones carried toward target organs in the body
  • Communication is via chemicals
• Hormones

  • Chemical substances that circulate through the bloodstream and only affect target cells 
  • Produced in large quantities but disappear quickly AND Effects are very powerful  
• Psychological changes triggered by adrenaline

  • Dilates pupils - focus on stressful situation  
  • Diverts blood to muscles - they increase blood flow and allow for muscle contraction   
  • High blood-glucose level 
  • Increase blood pressure  
  • Increased heart rate 
• Process of fight or flight response

  1. Works with the autonomic nervous system - ANS 
  2. Stressor perceived  
  3. Hypothalamus triggers activity in the sympathetic part of the ANS 
  4. ANS changes from normal resting state to aroused state  
  5. Stress hormone - adrenaline released from adrenal medulla (part of the adrenal gland) into blood stream 
  6. Triggers psychological changes   
  7. Happens in an instant - acute response