BIOL 1911 Chapter 48.1: 48.1 – Neuron structure and organization reflect function in information transfer
29 Apr 2018
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48.1 – Neuron structure and organization reflect function
in information transfer
• Neuron = nerve cell that transfers information within the body
o Communication by neurons by long-distance electrical signals and short-distance chemical signals
o Specialized structure allows them to use pulses of electrical current to receive, transmit and regulate the flow
of information over long distances within the body
o Neurons often rely on chemical signals that act over very short distances in transferring information from one
cell to another
o All neurons transmit electrical signals within the cell in an identical manner
o The particular connections made by the active neuron are what distinguish the type of information being
transmitted
o Interpreting nerve impulse involves sorting neuronal paths and connections
▪ Processing carried out largely in groups of neurons organized into a brain or into simpler clusters
called ganglia
• Nerve cell exemplifies the close fit of form and function that arises over the course of evolution
Nerve Structure and Function
• Ability of a neuron to receive and transmit information is based on a highly specialized organization
• Cell body = a ’ a a a
• Dendrites = highly branched extensions that come of the cell body; receive signals from other neurons
• Axon = a single extension of the cell body that transmits signals to other cells
o Often much longer than dendrites
o Cone-shaped base of an axon (axon hillock) is where signals that travel down the axon are generated
o An axon usually divides into many branches near its end
• Synapse = the junction between two nerve cell into which the branched end of one axon trasmitts information
o Synaptic terminal = the part of each axon branch that forms this specialized junction
• Neurotransmitters = chemical messengers that pass information from the transmitting neuron to the receiving cell;
exist at most synapses
o (in describing a synapse)
o Presynaptic cell = transmitting neuron
o Postsynaptic cell = neuron, muscle, or gland cell that receives the signal
• Glial cells = supporting cells required by neurons of vertebrates and most invertebrates
o Outnumber neurons in the mammalian brain by 10- to 50- fold
o Nourish neurons, insulate axons of neurons, and regulate extracellular fluid surrounding neurons
o Sometimes function in replenishing certain groups of neurons and in transmitting information
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