nervous system & endocrine system

• the nervous system


  A network of cells in the human body that is our primary internal communication system
• functions of the nervous system

  1. To collect, process and respond to information in the environment

  2. To coordinate the working of different organs and cells in the body
• What does the brain do as part of the CNS?

  It is the centre of all conscious awareness.

  
  

  The outer layer of the brain is highly developed in humans and distinguishes our higher mental functions from animals
• What does the spinal cord do as part of the CNS?

  - It is an extension of the brain.

  - It is responsible for reflex actions
• peripheral nervous system (PNS)


  It transmits messages via neurones to and from the CNS

  It is divided into the autonomic nervous system (ANS) & the somatic nervous system (SNS).
• autonomic nervous system (ANS)


  - Controls vital functions ( breathing, heart rate, digestion, sexual arousal and stress responses)

  - Control centres are in the brain stem

  - Contains motor pathways

  - It has 2 divisions - sympathetic and parasympathetic
• somatic nervous system (SNS)

  - Controls muscle movement & receives information from sensory receptors

  - Carries commands from the motor cortex

  - Contains sensory & motor pathways
• the endocrine system


  It instructs glands to release hormones into the bloodstream
• thyroid gland


  - Produces thyroxine

  - Affects cells in the heart & increases heart rate

  - Affects other cells to increase metabolic rates which affects growth rates
• adrenal gland


  - Produces adrenaline

  - Causes physiological changes - increased heart rate/breathing rate

  - Vital for fight or flight
• fight or flight response

  - Stressor occurs

  - ANS changes from a parasympathetic (resting) state to a sympathetic state (physiologically aroused)

  - Pituitary gland releases ACTH

  - ACTH affects cells in the adrenal gland - causes them to release adrenaline

  - Physiological changes occur in the body (increased heart rate, increased breathing rate , pupils dilates , inhibits digestion , inhibits saliva production and contracts the rectum) caused by adrenaline

  - creates physiological arousal needed for fight or flight