Psych Reading for January 18th Pages 82 91 Biological Psychologists Neuroscientists Researchers who study the relationship between the nervous system and behavior Nerve Cells Communication Portals Neurons The brain s communicators o The functioning of our brain depends on cross talk among neurons o Neurons Nerve cells exquisitely specialized for communication with each other o Neurons have long extensions which help them to respond to stimulation from other neurons and communicate o Neurons contain several other components that collaborate to help our nervous systems function new cell components The Cell Body The central region of the neuron manufactures Dendrites Branchlike extensions for receiving information from other neurons spread out to listen in on information from neighboring neurons and pass it on to the cell body Axons Long tail like extensions protruding from the cell body specialized for sending messages to other neurons Very thin near the cell body which creates a trigger zone an area that s easily activated Axon Terminal A knoblike structure at the far end of the axon Contains o Synaptic Vesicles Tiny spheres that contain Neurotransmitters Chemical messengers that neurons use to communicate with each other When the synaptic vesicle reaches the end of the axon terminal it bursts releasing neurotransmitters Synapses Miniscule fluid filled spaces between neurons through which neurotransmitters travel Consists of Synaptic Cleft A gap into which neurotransmitters are released from the axon terminal surrounded by small patches of membrane on each side one on the sending axon on the first neuron and the other on the receiving dendrite of the second neuron Glial Cells Surround the synapse and provide protective scaffolding for the neurons they hold in place Oligodendrocyte Promotes new connections among nerve cells and releases chemicals to aid in healing o Produces an insulating wrapper around axons called the myelin sheath o Myelin Sheath Contains nodes which help the neuron conduct electricity more efficiently Neural signal jumps from node to node speeding up its transmission Neurons respond to neurotransmitters by generating electrical Resting Potential When here are no neurotransmitters acting activity on the neuron Threshold When the electrical charge inside the neuron reaches a high enough level relative to the outside causes an action potential Action Potentials Abrupt waves of electric discharge triggered by a change in charge inside the axon Action potentials originate in the trigger zone near the cell body and continue all the way down the axon to the axon terminal During an action potential positively charged particles flow rapidly into the axon and then just as rapidly flow out causing a spike in positive charge followed by a sudden decrease in charge with the inside charge ending up at a slightly more negative level than its original resting value When the electrical charge reaches the axon terminal it triggers the release of neurotransmitters chemical messengers into the synapse Absolute Refractory Period A brief interval during which another action potential can t occur Limits the maximal firing rate the fastest rate at which a neuron can fire Chemical Communication Neurotransmission Whereas electrical events transmit information within neurons chemical events initiated by neurotransmitters orchestrate communication among neurons After neurotransmitter molecules are released into the synapse they bind with receptor sites along the dendrites of neighboring neurons Different receptor sites recognize different types of neurotransmitters Neurotransmission can be halted by reuptake of the neurotransmitter into the axon terminal a process by which the synaptic vesicle reabsorbs the neurotransmitter Neurotransmitters o Different neurotransmitters are different messengers each with slightly different things to say o Glutamate and GABA Gamma Aminobutyric Acid The most common neurotransmitters in the central nervous system Glutamate Rapidly excites neurons increasing the likelihood that they ll communicate with other neurons GABA Inhibits neurons dampening neural activity o Acetylcholine Plays roles in arousal selective attention sleep and memory o Monoamines o Neuropeptides Act like neurotransmitters but their roles are typically more specialized Endorphins Specialized role in pain reduction o Anandamide Eating motivation memory and sleep Durgs that interact with neurotransmitter systems are called psychoactive meaning they affect mood arousal or behavior Agonists Increase receptor site activity Antagonists Decrease receptor site activity
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