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106 Cards in this Set
- Front
- Back
Neurotransmitters are either:
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-simple amino acids (GABA, Glutamate)
-synthesized within neurons (indogenous) |
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What are some assumptions about drugs?
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-viewed as "exogenous" (from outside) chemicals
-alter neuron activity -have effects at low doses |
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Most anesthetic drugs affect synaptic action in one of two ways:
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-blocking the release of transmitter from the pre-synaptic cell
-blocking the receptors on the post-synaptic cell |
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What is pharmacokinetics?
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study of drug absorption, distribution within body, and elimination
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What are the different routes of drug administration into the body? (5)
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-intravenous (IV)
-intraperitoneal (IP- into the gut--lab animals) -subcutaneous (under the skin) -intramuscular (IM- into the muscle) -oral |
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What is the dose-response (DR) curve?
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depicts the relation between drug dose and magnitude of drug effect
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Different drugs have different D-R curves. Why?
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-different sites of action
-different levels of affinity |
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What is affinity?
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the readiness with which two molecules attach
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A drug with high affinity will produce effects at _____ concentrations.
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low
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A drug with low affinity must be administered in _____ doses.
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high
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The effectiveness of two drugs with same sites of action can vary considerably if they can have different ___________ for their binding sites.
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affinities
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Ideally, a drug should have high affinity for sites of action that produce ______________.
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therapeutic effects
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Ideally, a drug should have a low affinity for sites of action that produce ________________.
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toxic side effects
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Why do drug effects diminish with repeated administration?
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-changes in number of brain receptors for drug
-decrease in affinity of receptors to bind drug |
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_________ is associated with tolerance.
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Withdrawal
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What is sensitization?
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drug effects increase with repeated administration
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What is tolerance?
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drug effects diminish with repeated administration
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What is a placebo?
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an innocuous substance without a specific physiologic effect
-subject's belief that they receive a medication can trigger real physiological responses that mimic the effect of a drug |
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What are the 4 basic steps of a NT?
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-synthesized
-stored -released -terminated |
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A receptor's affinity for a specific molecular structure, a ligand, is similar to the relationship between what?
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a "lock and key"
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A drug molecule with the "best fit" to the receptor will:
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elicit the greatest response from the cell
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When a ligand bonds:
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the electrical properties of that cell changes
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Drug occupation of a receptor either serves as an....
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-agonist
-antagonist |
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What is an agonist?
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-a drug occupation of a receptor
-binds to and activates receptors -facilitates the NT effects |
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What is an antagonist?
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-a drug occupation of a receptor
-a receptor blocker that binds but does not activate -will interfere with the binding of NT |
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Each NT has multiple ________ ________ on the postsynaptic membrane. AND Each receptor has one or more types of _______ ________ allowing different substances to affect the receptors function.
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-receptor types
-binding sites |
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Describe primary mechanisms of drugs: Affecting release of NT (presynaptic).
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-affects neurons ability to release NT
-presynaptic heteroreceptor |
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Describe primary mechanisms of drugs: Affecting reception of NT (postsynaptic).
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-direct agonists
-a drug that binds and activates |
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Describe primary mechanisms of drugs: Affecting synapse (synaptic).
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-direct antagonists (receptor blocker)
-blocking reuptake -inactivation NT |
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What happens when drugs occupy receptor's binding cites?
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-does not open ion channels (just blocks receptor)
-prevents NT from opening the ion channel |
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True of false: Some drugs open ion channels permanently.
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True (or for a very long time)
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Describe barbiturates.
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-make many of inhibitory synapses stick "open"
-thus, barbiturates produce "super-inhibition" |
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What is "super-inhibition" and what does this produce?
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-the inability to excite neurons
-produces: deep sleep, unconsciousness, and eventually death when all neurons stop firing |
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What is presynaptic heteroceptor?
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-an axoaxonic synapse
-one axon synapses on another axon |
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What does the first neuron cause?
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either presynaptic inhibition or facilitation of the second one
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What is presynaptic inhibition?
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activation of receptors that inhibit the opening of calcium channels
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What is presynaptic facilitation?
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activation of receptors that facilitate the opening of calcium channels
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What are the 2 types of termination of postsynaptic potential?
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-reuptake into button
-destruction of transmitter by enzyme |
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Describe prolongation of postsynaptic potential.
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-acting as agonists, drugs can interfere with any of these processes:
--deactivation of molecules responsible for reuptake --binding with enzyme that normally destroys transmitter (e.g., acetylcholinesterase can be made ineffective which usually destroys acetycholine) |
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Where are NTs synthesized and released from?
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presynaptic terminal
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NTs have brief effects on what? AND what are these effects known as?
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-postsynaptic membrane
-action potentials (IPSPs and EPSPs) |
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Describe the creation of NTs.
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most are synthesized in the cytoplasm of the terminal buttons and stored into newly formed synaptic vesicles
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What are the primary NTs?
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-Acetylcholine (ACh)
-Monamines -Amino Acids |
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Name the primary monamines?
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-Dopamine (DA)
-Norepinephrine (NE) -Serotonine (5-HT) |
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Name the primary amino acids.
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-Glutamate
-GABA -Glycine |
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Which NT is the primary efferent transmitter in the CNS?
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Acetylcholine (ACh): axons and terminal buttons containing ACh are distributed widely throughout the brain
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All muscular activity is accomplished by the release of what?
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ACh
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In the periphery, ACh neurons are found where? AND what is their function?
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- found at neuromuscular junction (stored here)
-cause muscles to contract |
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Describe ACh neurons in the brain.
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are distributed widely and are generally facilitatory in the brain
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What function do ACh neurons have in the dorsal pons?
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REM sleep
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What function do ACh neurons have in the medial septum?
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control hippocampus for memory functions
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What function do ACh neurons have in the basal forebrain?
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-activating cerebral cortex
-facilitating learning, especially perceptual learning |
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What enzyme is ACh deactivated in the synapse by? AND where is this enzyme present?
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-the enzyme acetylcholinesterase (AChE)
-in the PS membrane |
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What reactivates ACh?
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choline
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Describe Botulinum toxin. AND tell how it affects ACh.
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-Botox: a bacteria that can grow in improperly canned food. A teaspoon could kill the human population. For SLP, inserted into VFs for spasmodic dysphonia.
-an ACh antagonist (prevents presynaptic release of ACh) |
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What are potential symptoms of black widow spider venom? AND tell how it affects ACh.
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-twitching, trembling, paralyzed breathing, convulsions, and in extreme cases, death
-ACh agonist (triggers the release of ACh) |
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What do insecticides do to insects and to humans? AND tell how they affect ACh.
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-kill insects by deactivating AChE; may have little effect on humans as our blood contains enzymes that destroys them
-ACh agonist |
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Describe Myasthenia Gravis. AND describe what drugs can do for this.
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-caused by an attack of a person's immune system against ACh receptors located in skeletal muscles
-person becomes weaker as muscle becomes less responsive to ACh -drugs such as neostigmine (ACh agonist) can return some strength-- produce a more prolonged effect of ACh by inhibiting AChE |
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Describe curare as it relates to ACh.
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-ACh antagonists
-blocks ACh receptors found in muscle -produces paralysis -used for poisoned darts for hunting causing animals to collapse and cease breathing (extracted from several different species of plants in South America) -used medically to relax a muscle undergoing surgical procedure |
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True or false: Monoamines are produced by several systems of neurons in the brain.
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True
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Why is Dopamine (DA) a double duty transmitter?
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produces both excitatory and inhibitory PSPs depending on the postsynaptic receptor
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What is Dopamine (DA) important for?
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-movement
-attention -learning -reinforcing effects of drugs that people abuse |
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Describe Parkinson's.
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a movement disorder that is characterized by: resting tremors, rigidity of limbs, poor balance, difficulty in initiating movements, hypokinetic dysarthria
-caused by degeneration of the dopaminergic neurons that connect the substantia nigra with the caudate nucleus |
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Where does the substantia nigra get its black color from?
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-melanin which is a natural by-product that is produced by the breakdown of DA
-dissection of this region in individuals with Parkinson's reveals only a pale color |
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Name AND describe the drug that alleviates some symptoms associated with Parkinson's.
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L-DOPA
-a precursor of DA that, unlike DA, can pass the blood-brain barrier -causes more DA to be synthesized and released by surviving dopaminergic neurons |
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What is Norepinephrine (NE)?
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-a hormone produced by the adrenal glands that serves as a NT in the brain
-most regions of the brain receive input from NE neurons |
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Where are the cell bodies of NE located in?
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-pons
-medulla -thalamus |
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What is the activation of NE transmitters important for?
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vigilance--attentiveness to events in the environment
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What effect does the NE transmitter have on the postsynaptic neuron?
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generally excitatory
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What does serotonin (5-HT) play a role in the regulation of?
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-mood
-eating -sleep -arousal -pain -dreaming |
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What is a 5-HT precursor?
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tryptophane ("turkey effect")--produces more serotonin in the brain
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Where are 5-HT neurons found?
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in the pons and medulla
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What effect does LSD have on 5-HT?
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agonist that stimulates 5-HT receptors
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What effect does Fenfluramine have on 5-HT?
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-agonist that facilitates the release of 5-HT and inhibits its reuptake
-suppresses appetite |
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Why do drugs such as LSD and Fenfluramine, which are both agonists for 5-HT, produce different effects?
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they have different receptors so they cause different effects on the neuron
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What effect does Fluoxetine (Prozac) have on 5-HT?
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agonist that inhibits reuptake of 5-HT
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What are the most common transmitter substances?
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amino acid NTs
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True or false: Amino acid NTs are found in only complex nervous systems and were likely late to evolve.
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False: found in very primitive nervous systems, perhaps first to evolve
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What is the general modulating role of amino acid NTs?
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-effect is to raise and lower the threshold of excitation (bias), thus affecting the rate at which APs can occur
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What effect does the amino acid NT GABA have?
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inhibitory (IPSP - hyperpolarizing effects--makes cell more negative--cell less likely to fire)
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What effect does the amino acid NT Glutamate have?
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excitatory (EPSP - depolarizing effects)
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What does GABA stand for?
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Gamma-aminobutyric-acid
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What two receptors have been identified for GABA?
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GABAa and GABAb
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What is the primary inhibitory transmitter substance for GABA? AND what does it do?
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GABAb receptors: open K+ channels, producing hyperpolarizing postsynaptic potentials
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What would happen to the brain without the inhibitory effects of GABA?
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-brain would become unstable (seizures)
-Epilepsy: may be caused by decline of GABA-secreting neurons |
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What is the principle excitatory transmitter substance in the brain and spinal cord?
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glutamate (almost all neurons in the brain are influenced by glutamate)
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What is the function of glutamate?
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-depolarizes neurons and increases cell excitability
-activates postsynaptic neurons by glutamate receptor-linked Na+/Ca++ channel |
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True or false: Glutamate is produced in abundance by the cell's metabolic processes.
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True
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What receptors mediate synaptic plasticity?
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AMPA receptors
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What is synaptic plasticity?
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means that the brain's pathways are capable of changing
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What will the lack of AMPA receptors do?
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make it difficult to learn/re-learn new information
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What happens with glutamate after a brain injury?
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-neurons release glutamate onto nearby neurons which become excited, overloaded with calcium and die
-destruction of the cell is caused by excessive CA++ activating enzymes within the postsynaptic cell -damage may be stopped by drugs that block these receptors |
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Describe Glycine.
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-an inhibitory NT in spinal cord and lower portions of the brain
-ionotropic receptor that controls chloride channel |
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What does the removal of inhibitory effect (caused by glycine NT) cause the muscle to do?
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to contract continuously (Tetanus, Strychnine)
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What is tetanus?
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-lockjaw
-bacteria releases chemical that prevents the release of glycine |
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What is strychnine?
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-serves as a glycine antagonist causing convulsions and death
-found in seeds of a tree found in India |
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What effects do narcotics have? AND give some examples.
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-effects ranging from mild dulling of the senses, pain relief, and sleep, to stupor coma, and convulsions
-egs: morphine, codeine, heroin, opium, OxyContin |
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Define general depressants. AND give some examples.
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-a drug or agent that has the effect of slowing the rate of the body's vital functions
-egs: alcohol, diazepam (Valium), chlordiazepoxide (librium), barbituates, methaqualone (Quaalude), "glue" |
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What are barbituates? AND give some examples.
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-prescription sedatives
-egs: amobarbital (Amytal), pentobarbital (Nembutal), secobarbital (Seconal) |
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Give examples of stimulants.
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cocaine, caffeine, amphetamine
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Give examples of hallucinogens.
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LSD, Mescaline, Psilocybin, Peyote, marijuana
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What drugs typically cause decreased salivation?
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-Oxybutin (Ditropan)
-Diphenhydramine (Benadryl) |
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What is GERD? AND what drugs often cause this?
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-gastroesophageal reflux
-Nifedipine (Procardia) and Albuteral |
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What drugs often cause impaired motor function?
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-Haldol
-Thorazine -Risperidone |
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What drugs typically cause impaired cognition and attention?
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-Diazepam (Valium)
-Lorazepam (Ativan) |
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What drugs typically distort taste?
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-Chemotherapy
-Tetracycline |