chapter 4 chemical basis of behavior

chapter 4 chemical basis of behavior - Chapter 4 The...

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Chapter 4 The Chemical Bases of Behavior: Neurotransmitter and Neuropharmacology I. Neurochemistry – The Branch of neuroscience concerned with the fundamental chemical composition and processes of the nervous system II. Neuropharmacology – the scientific field concerned with the discovery and study of compounds that selectively affect the functioning of the NS. III. Many Chemical Neurotransmitters Have Been Identified a. To classify a substance as a classic neurotransmitter, we must show that i. The substance exists in the presynaptic axon terminals ii. The presynaptic cell contains appropriate enzymes for synthesizing the substance iii. The substance is released in significant quantities when action potentials reach the terminals iv. Specific receptors that recognize the realized substance exist on the postsynaptic membrane v. Experimental application of the substance produces changes in postsynaptic potentials vi. Blocking relaese of the substance prevents presynaptic nerve impulses from altering the activity of the postsynaptic cell. b. Amine neurotransmitters: a neurotransmitter based on modifications of asingle amino acid nucleus c. Amino acid neurotransmitter: a neurotransmitter that is itself an amino acid such as GABA, glycine, or glutamate d. Peptide neurotransmitters made up of short chains of amino acids. e. Gas neurotransmitters, soluble gases that diffuse between neurons to alter ongoing processes Family and subfamily Transmitter(s) Amines - Quaternary amines - Monoamines Acetylcholine (ACh) Catecholamines: NE, epinephrine (adreneline), DA Indoleamines: Serotonin (5-hydroxytryptamine; 5-HT), melatonin Amino Acids Gamma-aminobutyric acid (GABA), glutamate, glycine, histamine Neuropeptides - Opioid peptides Enkephalins: Met-enkephalin, leu-enkephalin Endorphins: B-endorphin Dynorphins: Dynorphin A Peptides Oxytocin, substance P, cholecystookinin (CCK), casopressin, neuropeptide Y (NPY), hypothalamix releasing hormones Gases Nitric oxide, carbon monoxide f. NT affect their targets by interacting with receptors, protein molecules embedded in the postsynaptic membrane that recognize the transmitter g. The transmitter molecule binds to the receptor, changing its shape to open an ion channel (fast, ionotropic receptors—a receptor protein that includes an ion channel that is opens when the receptor is bound by an agonist), or altering chemical reactions within the target cells (slow, metabotropic receptors—a type of transmitter receptor that does not contain an ion channel but may, when activated, use a G protin system to open a nearby channel). h. The different receptor subtypes may trigger very different responses in target cells, and have different anatomical distributions within the NS i. A substance that binds to a receptor is termed a ligand and typically has one of 3 effects i. 1) when bound to a receptor, a ligand classified as an agonist initiates the normal effects of the receptor. Binds a receptor molecule and initiate a response like that of another
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chapter 4 chemical basis of behavior - Chapter 4 The...

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