The basic pathway for a nerve impulse is described by the stimulus response model

  • A stimulus is a change in the environment (either external or internal) that is detected by a receptor
  • Receptors transform environmental stimuli into electrical nerve impulses
  • These impulses are then transmitted via neurons to the central nervous system where decision-making occurs
  • When a response is selected (consciously or unconsciously), the signal is transmitted via neurons to effectors
  • Effectors are organs (either muscles or glands) that produce a response to a stimulus
  • A response is a change in the organism resulting from the detection of a stimulus

Overview of the Stimulus-Response Pathway


Three types of neurons are required to transmit information via the stimulus-response pathway:

  • Sensory neurons transmit information from sensory receptors to the central nervous system (CNS)
  • Relay neurons (interneurons) transmit information within the CNS as part of the decision-making process
  • Motor neurons transmit information from the CNS to effectors (muscles or glands), in order to initiate a response

While these three types of neurons share common features, their basic structure may differ slightly according to their function

  • This includes their length, cell body (soma) position and the comparative distribution of dendrites and axon terminals

Types of Nerve Cells

types of neurons