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Chapter 3

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Dax Urbszat

Psychology Chapter 3 Review: The Biological Basis of Behavior Nervous tissue: the basic hardware  The cells in the nervous system fall into two categories: glia & neurons o Neurons  individual cells in the nervous system that receive, integrate, and transmit information.  Soma  cell body, which contains the cell nucleus and much of the chemical machinery common to most cells  Dendrite (dendritic trees)  parts of a neuron that are specialized to receive information  From the dendrite, information flows into the cell body and then travels away from the soma along the axon  Axon  a long, thin fibre that transmits signals away from the soma to other neurons, muscles or glands. o in humans, many axons are wrapped in cells with a concentration with a white fatty substance called myelin  myelin sheath  insulating material derived from glial cells, that encase some axons o speeds up the transmission of signals that move across the axon o if the myelin sheath deteriorates, then signals might not be transmitted effectively o multiple sclerosis  loss of muscle control due to degeneration of myelin sheaths  Terminal buttons  the axon ends with these. They are small knobs that secrete chemicals called neurotransmitters o These chemicals serve as messengers that may activate neighboring neuron  Synapses  point at which neurons interconnect.  Synapse  a junction where information is transmitted from one neuron to another  PROCESS SUMMARY  o Information received at the dendrite  passed on through the soma along the axon  transmitted to the dendrites of other cells at the meeting point called synapses  Glia  are cells found throughout the nervous system, that provide various types of support for neurons o Smaller than neurons but outnumber them 10:1 o Account for 50 % of the brains volume o Supply nourishment to neurons o Help remove neuron’s waste products o Provide insulation around axons o Gradual deterioration of glial cells may contribute toAlzheimer’s disease o May be involved in chronic pain and schizophrenia and mood disorders The Neural Impulse: Using Energy to Send Information  Resting potential  of a neuron is its stable, negative charge when the cell is inactive  Action potential i is a brief shift in a neurons electrical charge that travels along the axon  Absolute refractory period  is the minimum length of time after an action potential, during which another action potential cannot begin o 1-2 milliseconds o Followed by a relative refractory period where neuron can fire but its threshold for firing is elevated so more intense stimulation is required to initiate an action potential  The all or none law  either the neuron fired or it doesn’t, and its action potential are all the same size, all or nothing event  Synaptic cleft  a microscopic gap between the terminal button of one neuron and the cell membrane of another neuron o Signals have to cross this gap to permit neurons to communicate o Presynaptic neuron  neuron that sends signals across the gap o Postsynaptic neuron  neuron that receives the signals  Neurotransmitters  chemicals that transmit information from on neuron to another o arrival of an action potential at the terminal button of an axon triggers the release of a neurotransmitter o acetylcholine  controlling skeletal muscles/ regulation of attention, arousal and memory o dopamine  control of voluntary movement, pleasurable emotions/ decreased level = Parkinson’s disease / over-activity associated with schizophrenia o norepinephrine  contributes to modulation of mood and arousal o serotonin  regulation of sleep, wakefulness, eating, aggression/ abnormal levels may lead to depression and OCD/ o GABA inhibitory transmitter/ contribute to pain relief, and some pleasurable emotions o Endorphins  resemble opiate drugs in structure and effects/ contribute to pain relief and some pleasurable emotions  post synaptic potential (PSP)  a voltage change at a receptor site on a postsynaptic cell membrane o when a neurotransmitter and a receptor molecule combine, reactions in the cell membrane cause PSP o do not follow the all or none law like neurons  two types of cells can be sent from cell to cell  excitatory & inhibitory o excitatory PSP  a positive voltage shift that increases the likelihood that the postsynaptic neuron will fire action potentials o inhibitory PSP  negative voltage shift that decreases the likelihood that post synaptic neuron will fire action potentials  reuptake  a process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane o The neurotransmitters drift away from the receptor sites or are inactivated by enzyme that metabolize them into inactive forms. Most are reabsorbed through the reuptake process  agonist  is a chemical that mimics the action of neurotransmitter  antagonist chemical that opposes the action of a neurotransmitter  Parkinson’s disease  caused by decline in the synthesis of the neurotransmitter dopamine  Monoamines  include 3 neurotransmitters  o Dopamine  Used by neurons that control voluntary movements  Degeneration of such neurons in the specific area of the brain cause a disease marked by muscular rigidity, tremors, and reduced control over voluntary movements  Schizophrenia (irrational thought/ hallucinations/ poor contact with reality/ deterioration of routine adaptive behavior) o Norepinephrine  Depressive disorders o Serotonin  Regulation of sleep, wakefulness and eating behavior  Aggression and impulsive behavior in humans  Eating disorders  Glutamate  learning and activity  Endorphins  internally produced chemicals that resemble opiates in structure and effects  Central nervous system  brain and spinal cord o Protected by enclosing sheaths called meninges o Consists of
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