Walden NURS 6630 Psychopharmacology Study Guide questions and answers.

classic synaptic neurotransmission stimulation of a presynaptic neuron (e.g., by neurotransmitters, light, drugs, hormones, nerve impulses) causes electrical impulses to be sent to its axon terminal. These electrical impulses are then converted into chemical messengers and released to stimulate the receptors of a postsynaptic neuron. The synaptic cleft is the gap between the presynaptic neuron and the postsynaptic neuron; it contains proteins and scaffolding and molecular forms of "synaptic glue" to reinforce the connection between the neurons. Receptors are present on both sides of this cleft and are key elements of chemical neurotransmission. the soma is the command center of the nerve and contains the nucleus of the cell axon Neurons send information via an ____ that forms presynaptic terminals as the ____ passes by (en passant) or as the ____ ends axodendritic synaptic connections between the axon and dendrites of two neurons axosomatic synaptic connections between the axon and the soma axoaxonic synaptic connections between axons of the two neurons The chemical basis of neurotransmission is how chemical signals are coded, decoded, transduced, and sent along the way. The anatomical basis of neurotransmission is neurons and the connections between them, called synapses, sometimes also called the anatomically addressed nervous system, a complex of "hard-wired" synaptic connections between neurons, not unlike millions of telephone wires within thousands upon thousands of cables The cytochrome P450 (CYP) enzyme system mediates how the body metabolizes many drugs, including antipsychotics. The CYP enzyme in the gut wall or liver converts the drug into a biotransformed product in the bloodstream. After passing through the gut wall and liver, the drug will exist partly as unchanged drug and partly as biotransformed drug. agonist produces a conformational change in the G-protein-linked receptor that turns on the synthesis of second messenger to the greatest extent possible full agonist is generally represented by the naturally occurring neurotransmitter itself, although some drugs can also act in as full a manner as the natural neurotransmitter Constitutive activity in the absence of agonist, the receptor's conformation is such that it leads to a low level of activity Antagonists blocks agonists (both full and partial) from binding to G-protein-linked receptors, thus preventing agonists from causing maximum signal transduction and instead changing the receptor's conformation back to the same state as exists when no agonist is present Partial agonists stimulate G-protein-linked receptors to enhance signal transduction but do not lead to maximum signal transduction the way full agonists do G Protein-Linked Receptors: Mechanism Drugs can interact at this neurotransmitter binding site or at other sites (allosteric sites) on the receptor. This can lead to a wide range of modifications of receptor actions due to mimicking or blocking, partially or fully, the neurotransmitter function that normally occurs at this receptor. These drug actions can thus change which genes are expressed, and thus which proteins are synthesized and which functions are amplified, from synaptogenesis, to receptor and enzyme synthesis, to communication with downstream neurons innervated by the neuron with the G-protein-linked receptor. G Protein-Linked Receptors: Structure These receptors all have the structure of seven transmembrane regions, meaning that they span the membrane seven times. Each of the transmembrane regions clusters around a central core that contains a binding site for a neurotransmitter. Nicotine directly causes dopamine release in the nucleus accumbens by binding to α4β2-nicotinic postsynaptic receptors on dopamine neurons in the ventral tegmental area (VTA). In addition, _________ binds to α7-nicotinic presynaptic receptors on glutamate neurons in the VTA, which in turn leads to dopamine release in the nucleus accumbens. ________ also seems to desensitize α4β2 postsynaptic receptors on GABA interneurons in the VTA; the reduction of GABA neurotransmission disinhibits mesolimbic dopamine neurons and thus is a third mechanism for enhancing dopamine release in the nucleus accumbens. PFC, prefrontal cortex; PPT/LDT, pedunculopontine tegmental and laterodorsal tegmental nuclei. Serotonin (5-hydroxytryptamine [5HT]) is produced from enzymes after the amino acid precursor tryptophan is transported into the __________ neuron. The tryptophan transport pump is distinct from the serotonin transporter. Once transported into the _________ neuron, tryptophan is converted by the enzyme tryptophan hydroxylase (TRY-OH) into 5-hydroxytryptophan (5HTP), which is then converted into 5HT by the enzyme aromatic amino acid decarboxylase (AAADC). _________ is then taken up into synaptic vesicles via the vesicular monoamine transporter (VMAT2),