ABSTRACT
A receptive field of dendrites conducts impulses to the cyton and an axon conducts them away from the cyton to a specialized ending. These endings interface with another nerve cell or effector organ via a synaptic cleft. The transmission of impulses across a synaptic cleft is effected by the release of specialized chemical transmitters. Details of synaptic transmission are
Figure 22.2 The three main avenues of differentiation that can be followed by a primitive nerve cell: (a) a receptor neuron shown synapsing with another nerve cell; (b) an interneuron showing its role in connecting together a large number of other nerve cells; (c) a motor or effector neuron with an end-plate on a target organ shown here as a muscle fibre. (Adapted from Warwick R and Williams PL. Gray’s Anatomy, 35th edn. London: Longman, 1973.)
given in Chapters 23 and 24. Considerable variations exist in cell size and shape in both the CNS and the PNS. The main types of neuron are shown in Figure 22.3. The functions of motor and sensory neurons (types a and f in Figure 22.3) are described in detail in Chapter 23.
