the nervous system

• the nervous system detects and reacts to stimuli
• organisms need to respond to stimuli (changes in the environment) in order to survive
• a single-celled organism can just respond to its environment, but the cells of multicellular organisms need to communicate with each other first
• the nervous system is made up of different parts:

  • central nervous system (CNS)
  • sensory neurones
  • motor neurones
  • effectors
• CNS:

  • in vertebrates, this consists if the brain and spinal cord
  • in mammals, the CNS is connected to the body by sensory neurones and motor neurones
• sensory neurones:

  • the neurones that carry information as electrical impulses from the receptors to the CNS
• motor neurones:

  • the neurones that carry electrical impulses from the CNS to effectors
• effectors:

  • all your muscles and glands, which respond to nervous impulses