Psych 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 cells Monoamines 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 glands
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