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Definition
| where neurotronmitters are synthesized |
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Term
| action of neurotransmitter (definition) |
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Definition
| It is present in the presynaptic terminal and is released in amounts sufficient to exert a defined action on the post-synaptic neuron or effector organ (e.g., muscle). |
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Definition
| mimics the action of the endogenously released transmitter exactly (for example, it activates the same ion channels or second-messenger pathways in the the post-synaptic cell. |
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Term
| NTs definition by location |
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Definition
| specific mechanism exists for removing it from its site of action (the synaptic cleft). |
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Definition
| according to molecular weight. |
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Term
| larger of two main types of Nts |
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Definition
| Large, dense core neuropeptides (short polymers of amino acids), synthesized only in cell body. once released, must be transmitted from the cell body to the terminals before they can be released again. |
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Term
| smaller of two main types of NTs |
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Definition
| Small molecule transmitters packaged in small lucent vesicles, released via exocytosis at active zones near Ca2+ channels. The best-known neurotransmitters are of this type. synthesized in cell body or in terminal button, release can be rapid and sustained |
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Term
| neurotransmitter relationship to receptors |
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Definition
action does not depend on the chemical properties of the transmitter, but on the properties of the receptors that recognize and bind the transmitter.
Idea pioneered by German bacteriologist Paul Ehrlich (1900) who used “lock and key” analogy.
E.g., in vertebrates acetylcholine (ACh) at the neuromuscular junction is excitatory, but it slows the heart by acting on an inhibitory ACh receptor |
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Definition
| Receptors open or close ion channels, usually via a configurational change that results in the opening of a channel |
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Definition
| These receptors stimulate processes inside the cell producing small metabolites (e.g., cAMP) or protein kinases (enzymes that phosphorylate different substrate proteins), which result in the opening or closing of ion channels. indirectly influence NT release |
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Term
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Definition
Transmitter molecules that do not bind at the time of release to receptors on the post-synaptic cell are removed from the synapse via these channels.
Inside the pre-synaptic cells the molecules are broken down by monoamine oxydase (MAO), then reconstituted and “repackaged” into vesicles for re-release. |
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Term
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Definition
| most common excitatory neurotransmitter in the CNS (i.e., opens channels that allow positively charged sodium or calcium ions to enter). |
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Definition
| NMDA, AMPA, kainate receptors, and several metabotropic ones. |
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Definition
| important for learning and memory, in the process known as long-term potentiation (LTP) |
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Term
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Definition
glutamine, is released by glial cells and transported via special transporter channels from the glial cell into the neuron.
It is metabolized inside the cell body by the mitochondrial enzyme glutaminase. |
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Term
| glutamate after into synapse |
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Definition
| Once it has been sent to the terminal button and released into the synaptic cleft as a neurotransmitter, the molecules that do not bind to the post-synaptic receptors are taken back into nearby glial cells via re-uptake autoreceptors, then broken down into its precursor and transported into the cell all over again. |
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Term
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Definition
Glutamate in high concentrations in the extracellular fluid is highly toxic to neurons, but this occurs with neural injury.
Reduced blood flow to the brain (due to blockage or occlusion – i.e., ischemic stroke) results in atypically high levels of extracellular glutamate. This may be because there is not enough energy (mitochondria require oxygen) for reuptake channels to remove it from the synaptic cleft.
As a result, post-synaptic cells become swollen and the cells die |
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Definition
most common inhibitory neurotransmitter
(i.e., has the effect of opening channels to allow negatively charged chloride ions to enter) |
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Definition
| synthesized from glutamate by an enzyme found exclusively in the GABAergic neurons (i.e. those that secrete GABA as a neurotransmitter), together with a substance which is derived from Vitamin B6. |
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Term
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Definition
dietary deficiency of Vitamin B6 (e.g., in infant formula) can lead to inadequate GABA synthesis.
Since GABA inhibits cells from firing, its absence can lead to epileptic seizures and death. |
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Term
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Definition
| removed from the synaptic cleft by high-affinity re-uptake receptors in the pre-synaptic neuron and nearby glial cells, and is broken down by enzymes produced by the mitochondria in the cell body. |
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Term
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Definition
Found in many parts of the brain.
Nicotinic receptors (excitatory: leads to influx of Na+ and efflux of K+) and muscarinic receptors (excitatory or inhibitory).
In dorsolateral pons, triggers REM sleep
In basal forebrain (nucleus basalis of Meynert), and hippocampus, activates cortex for learning.
At neuromuscular junction (NMJ), is responsible for all muscular movement.
Botulinium = antagonist |
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Term
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Definition
derived from the same precursor, the amino acid tyrosine, which is manufactured in the liver (with the help of the enzyme phenylalanine).
The first step is to convert tyrosine to L-dopa, which is then converted to dopamine (DA). |
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Term
| whatis norepinephrine derived from |
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Definition
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Term
| what is epinephrine derived from |
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Definition
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Term
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Definition
in the substantia nigra (black substance), located in the brainstem,
in the ventral tegmental area (medial and superior to the substantia nigra),
in the arcuate nucleus of the hypothalmus. |
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Term
| nigrostriatal pathway of dopamine |
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Definition
projects from the substantia nigra to the striatum (aka basal ganglia - mostly caudate and putamen).
In the striatum, DA binds to D1 and D2 receptors, and is important in the regulation of movement (see overhead). |
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Term
| pathology of nigrostriatal pathway of dopamine |
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Definition
| Lack of DA (for whatever reason) leads to symptoms that can include slow movement (bradykinesia), tremor, and rigidity (as in Parkinsonism), or chorea (as in Huntingdon’s). Anti-psychotic medication can also reduce DA and therefore result in tardive dyskinesia |
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Term
| mesolimic pathway of dopamine |
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Definition
These neurons project from the ventral tegmental area to the mesial limbic structures, including the nucleus accumbens, the mesial frontal, anterior cingulate, the amygdala, the septal nuclei, the hippocampus, and entorhinal cortex (see overhead).
D2 and D3 receptors in particular associated with this path. |
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Term
| mesolimbic pathway of dopamine pathology |
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Definition
| DA deficiency associated with depression; DA excess associated with pleasure (nucleus accumbens) and stereotyped / addictive behavior |
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Term
| three different roles of DA systems |
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Definition
Nigrostriatal – basal ganglia – movement
Mesolimbic – ventral tegmental to limbic structures – mood
Mesocortical – ventral tegmental to neocortex – thought and memory. |
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Term
| interactions of DA and other systems |
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Definition
Current theories of schizophrenia, ADHD, etc. emphasize the possibility of an imbalance between the different DA pathways.
In animals, disruption of the mesocortical path leads to enhanced responsiveness of the mesolimbic path (Pycock). Thus PFC dysfunction could lead to disinhibition of BG.
Imbalance between levels of DA and 5HT (serotonin) leads to hallucinations. Thus it is likely to be the ratio between neurotransmitters, rather than absolute amounts in the body, that causes symptoms. |
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Term
| where is norepinephrine synthesized? |
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Definition
| Synthesized in the locus ceruleus (literally blue place) in the brainstem, below the wall of the 4th ventricle. |
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Term
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Definition
Amounts increase during stress due to stimulation from the hypothalamus.
Affects mood, memory, hormone production, and cerebral blood flow.
NE depletion affects sustained attention in the face of distraction. |
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Term
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Definition
| all metabotropic, and are sensitive to both epinephrine and norepinephrine. They are referred to adrenergic. They include alpha1 and alpha2 , and beta1, beta2, and beta3. (The latter is found only outside the CNS in fat tissue.) The adrenergic receptors have both excitatory and inhibitory effects, but behaviorally are generally excitatory. |
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Term
| what is seratonin derived from? |
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Definition
| Derived from the amino acid tryptophan (found in turkey and pasta); synthesized in CNS (raphe nuclei in brainstem), and enteric cells (autonomic nervous system) in the GI tract. |
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Term
| seratonin associated with... |
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Definition
| Affects cardiovascular and respiratory systems (vasoconstriction = common response)correlate with violent behavior. |
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Term
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Definition
| Associated with sleep disorders (destruction of raphe nucleii leads to persistent insomnia) and depression/suicide; reduced levels correlate with violent behavior. |
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Definition
| Produced by the amino acid histidine, found in large concentrations in the hypothalamus, which projects widely throughout the brain and spinal cord |
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Definition
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Definition
Functions include:
increased arousal / wakefulness, resulting in more general activity, thought to result from histamine binding to H1 receptors.
Other functions include:
constriction of smooth muscles of lungs, uterus, and stomach,
dilation of blood vessels, which increases permeability of their walls and lowers blood pressure;
stimulation of gastric acid in the stomach;
acceleration of heart rate.
Response to allergens.
Maintaining hibernation states in animals (adding histamine to the hippocampus results in greater difficulty arousing animals from hibernation). |
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