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Psychology (3,337)
PSYC 2410 (149)
Dan Meegan (42)
Chapter 3

Chapter 3 Review

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Department
Psychology
Course
PSYC 2410
Professor
Dan Meegan
Semester
Fall

Description
DefinitionsChapter 3 ReviewNeuronsNeurons specialized cells that are the basic building blocks of the nervous systemThese nerve cells are linked together in circuits like a computerVary in size and shape regardless of shapesize they have been sculpted to perform their function of receiving processing and sending messagesMore than 200 different types of neurons have been viewed through electron microscopesAt birth the brain contains 100 billion neuronsoIf each neuron were a cm long they could circle the world 24 timesNeurons are made up of three partsoCell Body Soma contains biochemical structures needed to keep the neuron aliveits nucleus carries the genetic info that determines how the cell develops and functionsoDendrites From the Greek word meaning treeemerges from the cell body branchlike fibresLike antennas that collect messages from other neurons and send them on to the cell bodyThe incoming info is combined and processedCan receive input from 1000 or more neighbouring neuronso AxonAn extension from one side of the neuron cell body that conducts nerve impulses to other neurons muscles or glandsAxon branches out to form a number of axon terminals as many as several hundredMay connect with dendritic branches from numerous neurons making it possible for a single neuron to pass messages to as many as 50 000 other neuronsThe structure of the dendrites and axons make trillions of interconnections in the brains making it capable of performing complex psychological activities that interest psychologistsNeurons are supported in functions by glial cellsoFrom the greek word for glueoSurround neurons and hold them in placeoManufacture nutrient chemicals that neurons need and form the myelin sheath around some axonsoAbsorb toxins and waste materials that might damage neurons and protects brainoSend out long fibres to guide newly divided neurons to their place in the brain during prenatal brain developmentoOutnumber neurons about 101 in the nervous systemBloodbrain specialized barrier in the brains blood vessels that screen out foreign substance while letting nutrients pass through to neuronsNerve Conduction An Electrochemical ProcessNeurons do two important thingsoGenerate electricityoRelease chemicalsNeurons have own chemical substances which isa source of energy like batteriesThey are surrounded by a cell membrane which not only protects the inner structures but also operates as a selective filter that allows certain particles in the body fluid around the cell to pass throughSurrounded by salty liquid environment highly concentration of sodium and carries a positive electrical charge and positively charged particles or ionsIt has other ions that are carrying negative charge as wellThe inside of the neuron is electrically negative n relation to the outside producing an electrical resting potential of about 70 millivoltsmV across the membraneNeurons at a resting state are polarizedThe Action PotentialAction Potential a nerve impulse resulting from the depolarization of an axons cell membraneDepolarization the reversal of the resting potential of a neurons cell membrane that produces the action potentialoRelease of an action potential to pressing the shutter release button on a cameraGraded Potentials a change in the electrical potential of a neuron that is proportional to the intensity of the incoming stimulation but not sufficient to produce an action potentialAction Potential threshold the intensity of stimulation excitatory minus inhibitoryneeded to produce an action potentialAllornone law the fact that an action potential is not proportional to the intensity off stimulation a neuron either fires with maximum intensity or it does not fire compare with graded potentialIon Channels special protein molecules located on the membrane of a neuron that control the entry and exit of specific ions such as sodium and potassiumMore information on how they work together is on p88The Myelin SheathMany axons that transmit info through the brain and spinal cord are covered by a tubelike myelin sheathMyelin Sheath a fatty insulating substance on the axon of some neurons that increases the speed of neural transmission
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