PSYC 1000U Lecture 3: The Brain
Document Summary
Brian controls all our behaviour except for simple reflexes. Changes to genes, the brain, and/or hormones often result in observable behaviour differences. The nervous system is comprised of two major types of cells: Neurons: cells that receive, integrate and transmit information (i. e. , permit communication). Features: soma (with nucleus), dendrites, axon, and myelin sheath, terminal branches. Glial cells (glia): cells that support neurons (i. e. , support communication). They provide nourishment to neurons, remove waste products, provide insulation around axons. Neurons transmit signals electrochemically (i. e. , chemicals cause an electrical impulse) Each neuron receives excitatory and inhibitory signals from many other neurons. When the excitatory signals minus the inhibitory signals exceed a minimum intensity (i. e. , threshold) the neuron fires. All-or-none response: a strong external stimulus can trigger more neurons to fire, and to fire more often, but it does not affect the action potentials strength or speed. Intensity of an action potential remains the same throughout the length of the axon.
