The role of neurotransmittersNeurotransmittersChemical substances that carry signals between neuronsReleased in response to action potentialsTravel from pre-synaptic neuron to post-synaptic neuron (mostly)ReceptorsProteins in post-synaptic membraneSelective for specific neurotransmittersMultiple types for one neurotransmitterReceptor typesIonotropicReceptor acts as ion channel for Na+ or K+Fast acting; binding leads directly to flow of ions across membraneMetabotropicSlower acting; works indirectlyG-proteinseparates from receptor on inside of cellcan catalyze various metabolic changesEvents ending transmitter influenceReuptakeabsorption into presynaptic cell for reuseEnzymatic deactivationbroken down by enzymes in synapseAutoreceptorsreceptors on presynaptic cellsignal to stop releasing neurotransmitterAction of psychotropic drugsSelectively alter the actions of one or more neurotrasmitters or receptorsAgonistsenhance neurotransmitter actionsAntagonistsinhibit neurotransmitter actionsMechanisms of effectbind/block receptorsproduction and release of neurotransmitterreuptake, deactivation, and autoreceptorsNeurotransmitter typesAcetylcholineImportant for motor controlBinds directly to musclesAlso involved in cognitive functionsAmino AcidsGABAinhibitory action throughout brainGlutamateexcitatoryoften released by glial cellsMonoaminesAltered amino acidsEpinephrine (adrenaline) and norepinephrinearousal and attentionDopaminemotivation, reward, and motor controlinvolved in many narcoticsSerotoninemotions; dreamingimportant in action of hallucinogensPeptidesShort chains of amino acidsAct as neuromodulatorsincrease or decrease effects of neurotransmittersEndorphinseuphoria and pain suppressioninvolved in effects of opiatesCommunication systemsThe Nervous SystemThe Central Nervous System (CNS)BrainSpinal cordThe Peripheral Nervous System (PNS)Somatic SystemExternal functionsAutonomic SystemInternal functionsSomatosensation, digestion, etc.Two types of efferent signals from CNS to PNSSympathetic Division:Prepares body for actionFight-or-flight responseCan be triggered by anxietyParasympathetic DivisionOpposite effects of sympathetic systemReturn body to resting stateSummary of nervous systemThe endocrine systemInfluences thought, emotions, and behaviorCommunicates through hormonesChemical substances released into bloodstream by endocrine glandsMore diffuse and enduring effects than neurotransmittersSteroidsImportant in tissue developmentAmino acids, peptidesCan function differently inside and outside blood-brain barrierCoordination between nervous and endocrine systemsHypothalamusNeural structure that influences endocrine systemReceives signals from rest of brain and directs pituitary via “releasing factor”PituitaryEndocrine gland at base of hypothalamusMaster gland: controls activity of other endocrine glandsPsych 301, 10/22/3 The Nervous System The role of neurotransmitters Neurotransmitters Chemical substances that carry signals between neurons Released in response to action potentials Travel from pre-synaptic neuron to post-synaptic neuron (mostly) Receptors Proteins in post-synaptic membrane Selective for specific neurotransmitters Multiple types for one neurotransmitter Receptor types Ionotropic Receptor acts as ion channel for Na+ or K+ Fast acting; binding leads directly to flow of ions across membrane Metabotropic Slower acting; works indirectly G-protein separates from receptor on inside of cell can catalyze various metabolic changes Events ending transmitter influence Reuptake absorption into presynaptic cell for reuse Enzymatic deactivation broken down by enzymes in synapse Autoreceptors receptors on presynaptic cell signal to stop releasing neurotransmitter Action of psychotropic drugs Selectively alter the actions of one or more neurotrasmitters or receptors Agonists enhance neurotransmitter actions Antagonists inhibit neurotransmitter actions Mechanisms of effect bind/block receptors production and release of neurotransmitter reuptake, deactivation, and autoreceptors Neurotransmitter types Acetylcholine Important for motor control Binds directly to muscles Also involved in cognitive functions Amino Acids GABA inhibitory action throughout brain Glutamate excitatory often released by glial cellsMonoamines Altered amino acids Epinephrine (adrenaline) and norepinephrine arousal and attention Dopamine motivation, reward, and motor control involved in many narcotics Serotonin emotions; dreaming important in action of hallucinogens Peptides Short chains of amino acids Act as neuromodulators increase or decrease effects of neurotransmitters Endorphins euphoria and pain suppression involved in effects of opiates Communication systems The Nervous System The Central Nervous System (CNS) Brain Spinal cord The Peripheral Nervous System (PNS) Somatic System External functions Autonomic System Internal functions Somatosensation, digestion, etc. Two types of efferent signals from CNS to PNS Sympathetic Division: Prepares body for action Fight-or-flight response Can be triggered by anxiety Parasympathetic Division Opposite effects of sympathetic system Return body to resting state Summary of nervous system The endocrine system Influences thought, emotions, and behavior Communicates through hormones Chemical substances released into bloodstream by endocrine glands More diffuse and enduring effects than neurotransmitters Steroids Important in tissue development Amino acids, peptides Can function differently inside and outside blood-brain barrier Coordination between nervous and endocrine systems Hypothalamus Neural structure that influences endocrine system Receives signals from rest of brain and directs pituitary via “releasing factor” Pituitary Endocrine gland at base of hypothalamus Master gland: controls activity of other endocrine
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