A columnist is someone who writes for publication in a series, creating an article that usually offers commentary and opinions. Columns appear in newspapers, magazines and other publications, including blogs. They take the form of a short essay by a specific writer who offers a personal point of view.
This positive spike constitutes the action potential: the electrical signal that typically moves from the cell body dlown the axon to the axon terminals. The electrical signal moves down the axon like a wave; at each 84 Ch apter 3 Biopsycholo gy point, some of the sodium ions that enter the cell diffuse to the neJ1.'t section of the axon, raising the charge past the threshold of excitation and triggering a new influx of sodium ions.
An action potential, which is the nerve impulse, occurs when a threshold is reached. Upon stimulation, the sodium gates open, Na+ flows into the axon, and the action potential swings up from -65mV to +40 mV.. The axon of a neuron conducts nerve impulses away from the cell body. Neurons that conduct messages from a sense organ to the central nervous system are called sensory, or afferent neurons. Those neurons that conduct an impulse from the CNS to a muscle or gland are called. motor, or efferent, neurons.