Ch 3-Bio Basis of Behavior

Ch 3-Bio Basis of Behavior - Chapter 3-Biological...

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Chapter 3-Biological Psychology 9/4/07-9/11/07 Neurons o 3 main parts Dendrites Receive messages from other neurons Cell body Contains the genetic information that determines cell function Also referred to as the soma Axons Conducts electrical impulses o Glial cells Glial cells surround the neuron and hold them in place Manufacture nutrient chemicals needed by neurons These cells also absorb toxins and waste materials o Nerve conduction Neurons have a resting potential of -70 millivolts, creating a state of polarization Neurons are surrounded by a salty liquid environment which has a high concentration of sodium ions (Na+) and chloride ions (CL-) The inside of the neuron has some positively charged potassium ions (K+) and MANY other negatively charged ions (called – anions) Hyper polarization When the chloride rushes into the cell and makes it more negative Ex) when alcohol enters the system this happens o The action potential Dendrites are stimulated by axons of other neurons Na+ ions flow into the neuron by action of ion channels, making the membrane voltage more positive (depolarization) If threshold is reached, then an action potential is propagated down the length of the axon. Action potentials work by the all-or- none principle (happens on the axon) Once a certain amount of force is exerted, nothing is going to stop it from happening o Ex) pressing a light switch Ions pass through channels in cell membrane Graphical representation of an action potential Na+ rushes in K- rushes out When the action potential reaches 30 millivolts the Na+ rushes in and K- rushes out, and the voltage returns to normal
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Chapter 3-Biological Psychology 9/4/07-9/11/07 o After-hyper polarization: starts a refractory period, where the neuron needs to recover for a short period o Resting membrane potential is lower than the membrane potential (normal potential) o The Myelin Sheath Insulation layer covers axons in the brain and spinal cord Allows for high-speed conduction
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Ch 3-Bio Basis of Behavior - Chapter 3-Biological...

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