endocrine system

• endocrine system

  = instructs glands to release hormones directly into the bloodstream. Hormones are carried towards target organs, communicates via chemicals.

  • acts more slowly than nervous system but has widespread powerful effects. Various glands in the body such as thyroid gland, produce hormones.
  • thyroid gland produces thyroxine which affects cells in the heart and increases metabolic rates.
  • pituitary gland= located in brain, called 'master gland' as it controls the release of hormones from other endocrine glands.
• fight or flight

  -when in stressful event, the hypothalamus activates the pituitary gland and this triggers activity in the sympathetic branch of autonomic nervous system.

  -The ANS changes from it's normal resting state to the physiologically aroused sympathetic state.

  -Adrenaline= stress hormone released into the bloodstream. Triggers physiological changes in the body which creates the physiological arousal necessary for the fight or flight response.
• continued- fight or flight response

  -Immediate and automatic= all happens in an instant as soon as the threat is detected. This is an acute response and an automatic reaction in the body.- increased heart rate+ breathing rate, dilates pupils, inhibits digestion+ saliva production.

  -parasympathetic action= once threat has passed, parasympathetic nervous system return to body to resting state. Actions are antagonistic to sympathetic system- acts as a 'brake' + reduces the activities of body that were increased.