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Unformatted text preview: 1 Psych 1 Principles of Psychology 7/08/09 Biological Psychology What are the components of the nervous system? How does the brain create mental processes and behavior? The cells of the nervous system Neurons Information processing cells of the nervous system. Approximately 100 billion neurons in the nervous system. Glia Support cells of the nervous system: insulation, clean-up, structural support.. 10 times more glia than neurons. Neurons Sensory neurons : carry information from the senses to the CNS Motor neurons : send commands to the muscles and glands 2 Neurons At rest, a neurons cell body holds a -70mV charge called the resting potential . This means that there are more negatively charged ions/proteins inside of the cell membrane than outside, I.e the cell is polarized . Neurons exploit the effects of equilibrium on concentration and electrical gradients to function in a highly articulate and complex manner. Sodium (Na + ) potassium (K + ) pumps keep sodium ions outside and potassium ions inside. Neural communication 1. Receptor sites on a neurons dendrites receive chemical signals from the axon endings, or terminal buttons of preceding neurons. 2. These signals cause ion gates to on the dendritic membrane to open and electrical charge to diffuse into the neurons cell body . Neural communication 3. The cell body computes the sum of the multiple inputs to its dendrites ( excitatory : influx of positive charge, inhibitory : influx of negative charge). Input magnitude depends on the location of the axodendritic connection, the duration and repetition of input. 4. The axon hillock , a region of the cell body just before where the axon comes out, awaits an increased positive charge inside the cell (-50mV), or threshold depolarization , which causes sodium gates to open and more sodium ions to rush in: this is the onset of an action potential ....
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