The Human Nervous System

• homeostatis


  regulation of internal conditions to maintain optimum conditions in response to internal/external changes
• enzymes work best in stable conditions to maintain optimum
• what does homeostatis control?

  blood glucose concentration

  body temperature

  water levels
• automatic control systems


  internal conditions stay as constant as possible

  nervous system

  hormone system
• stimulus


  change in environment
• receptor


  cell detects change in internal/external environment
• coordination centre


  receive and process info from receptors
• examples of coordination centres

  brain

  spinal cord

  pancreas
• effector


  carry out response

  restore optimum levels
• examples of effector


  muscle

  gland
• STIMULUS -> RECEPTOR -> COORDINATION CENTRE -> EFFECTOR -> RESPONSE
• parts of nervous system

  Central Nervous System

  nerves
• Central Nervous System (CNS)

  brain

  spinal cord
• how nervous system works

  receptor detects stimuli

  electrical impulses along sensory neurone to CNS

  impulse along motor neurone to effector

  muscle contracts, gland secretes hormones
• synapse


  gap between two neurones
• reflex arc


  receptor detects stimulus

  electrical impulse along sensory neurone to CNS

  chemical diffuses across to relay neurone

  impulse reaches synapse, chemical triggers impulse in motor neurone

  effector results in response
• reflexes


  automatic and rapid

  no decision making by conscious part of the brain