The Biological Bases of Behavior
Communication in the Nervous System * Nervous Tissue: The Basic Hardware * Neurons are individual cells in the nervous system that receive, integrate, and transmit information. * The soma, or cell body, contains the cell nucleus and much of the chemical machinery common to most cells. * Dendrites are the parts of a neuron that are specialized to receive information. * The axon is a long, thin fiber that transmits signals away from the soma to other neurons or to muscles or glands. * The axon ends in a cluster of terminal buttons, which are small knobs that secrete chemicals called neurotransmitters. * The Neural Impulse: Using Energy to Send Information * The Neuron at Rest: A Tiny Battery * The resting potential of a neuron is its stable, negative charge when the cell is inactive. * The Action Potential * An action potential is a very brief shift in a neuron’s electrical charge that travels along an axon. * The absolute refractory period is the minimum length of time after an action potential during which another action potential cannot begin. * The All-or-None Law * The neural impulse is an all-or-none proposition. * The Synapse: Where Neurons Meet * Sending Signals: Chemicals as Couriers * The synaptic cleft is a microscopic gap between the terminal button of one neuron and the cell membrane of another neuron. * Neurotransmitters are chemicals that transmit information from one neuron to another. * Receiving Signals: Postsynaptic Potentials * Postsynaptic potential is a voltage change at a receptor site on a postsynaptic cell membrane. * Reuptake is a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane. * Integrating Signals: A Balancing Act * The elimination of old synapses appears to play