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Questions and Answers
What role does dopamine play in the limbic system?
What role does dopamine play in the limbic system?
Which condition is associated with excessive dopamine levels?
Which condition is associated with excessive dopamine levels?
What is a consequence of removing the hippocampus?
What is a consequence of removing the hippocampus?
What are NMDA receptors primarily known for?
What are NMDA receptors primarily known for?
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How does dopamine affect blood flow in the periphery?
How does dopamine affect blood flow in the periphery?
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What is a possible effect of excess extracellular glutamate?
What is a possible effect of excess extracellular glutamate?
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What is the primary function of glutamate in the central nervous system?
What is the primary function of glutamate in the central nervous system?
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What initiates apoptosis in neurons following NMDA receptor activation?
What initiates apoptosis in neurons following NMDA receptor activation?
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Which of the following neurotransmitters is primarily involved in the sympathetic nervous system as a postganglionic transmitter?
Which of the following neurotransmitters is primarily involved in the sympathetic nervous system as a postganglionic transmitter?
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What is the primary effect of norepinephrine stimulation in the body?
What is the primary effect of norepinephrine stimulation in the body?
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Which group of molecules do norepinephrine, epinephrine, and dopamine belong to?
Which group of molecules do norepinephrine, epinephrine, and dopamine belong to?
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What is the primary enzyme responsible for the conversion of glutamate into glutamine?
What is the primary enzyme responsible for the conversion of glutamate into glutamine?
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What physiological response is attributed to epinephrine during stress?
What physiological response is attributed to epinephrine during stress?
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What percentage of all released glutamate comes from glutamine?
What percentage of all released glutamate comes from glutamine?
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From which part of the brain do norepinephrine-containing neurons primarily arise?
From which part of the brain do norepinephrine-containing neurons primarily arise?
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Which of the following substances serves as a primary source for glutamate formation in neuron cells?
Which of the following substances serves as a primary source for glutamate formation in neuron cells?
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Which neurotransmitter is synthesized from glutamate by glutamate decarboxylase?
Which neurotransmitter is synthesized from glutamate by glutamate decarboxylase?
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What effect does norepinephrine have on alertness and attention?
What effect does norepinephrine have on alertness and attention?
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Which condition may be treated with drugs that influence catecholamine levels?
Which condition may be treated with drugs that influence catecholamine levels?
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What type of receptor is GABAA considered?
What type of receptor is GABAA considered?
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What role does epinephrine play in glycogen metabolism?
What role does epinephrine play in glycogen metabolism?
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What effect do psychoactive drugs have on GABA?
What effect do psychoactive drugs have on GABA?
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Which of the following enzymes is responsible for the conversion of DOPA to dopamine?
Which of the following enzymes is responsible for the conversion of DOPA to dopamine?
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What is the primary role of β-blockers like atenolol in medical treatments?
What is the primary role of β-blockers like atenolol in medical treatments?
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How is glutamate primarily taken up into neurons and glial cells?
How is glutamate primarily taken up into neurons and glial cells?
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What is a common side effect of drugs developed to inhibit NMDA activation?
What is a common side effect of drugs developed to inhibit NMDA activation?
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What percentage of noradrenaline is typically reabsorbed via the uptake 1 mechanism?
What percentage of noradrenaline is typically reabsorbed via the uptake 1 mechanism?
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Which receptor type does norepinephrine primarily act on?
Which receptor type does norepinephrine primarily act on?
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What is noradrenaline also commonly known as?
What is noradrenaline also commonly known as?
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What is the consequence of combining sympathomimetics with MAO inhibitors?
What is the consequence of combining sympathomimetics with MAO inhibitors?
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Where is phenylethanolamine N-methyltransferase primarily located?
Where is phenylethanolamine N-methyltransferase primarily located?
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What is the main function of noradrenaline in the nervous system?
What is the main function of noradrenaline in the nervous system?
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What effect does the binding of benzodiazepine have on the GABAA receptor?
What effect does the binding of benzodiazepine have on the GABAA receptor?
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Which amino acid is serotonin derived from?
Which amino acid is serotonin derived from?
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What role does serotonin primarily play in the spinal cord?
What role does serotonin primarily play in the spinal cord?
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What is the primary mechanism for reducing excess serotonin activity in the body?
What is the primary mechanism for reducing excess serotonin activity in the body?
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Which enzyme is responsible for the catabolism of serotonin?
Which enzyme is responsible for the catabolism of serotonin?
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What characterizes 5-HT1A receptors in the nervous system?
What characterizes 5-HT1A receptors in the nervous system?
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What is a consequence of increased serotonin levels in the body?
What is a consequence of increased serotonin levels in the body?
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What is the significance of HIAA in urine testing?
What is the significance of HIAA in urine testing?
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What role does catechol-O-methyl-transferase (COMT) play in catecholamine dynamics?
What role does catechol-O-methyl-transferase (COMT) play in catecholamine dynamics?
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What effect does cocaine have on catecholamines?
What effect does cocaine have on catecholamines?
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What condition can elevated levels of metanephrines and vanillylmandelic acid (VMA) indicate?
What condition can elevated levels of metanephrines and vanillylmandelic acid (VMA) indicate?
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What neurotransmitter is primarily responsible for the control of voluntary movement?
What neurotransmitter is primarily responsible for the control of voluntary movement?
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Damage to which dopamine-rich tract is associated with Parkinson’s disease?
Damage to which dopamine-rich tract is associated with Parkinson’s disease?
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Which enzymatic pathway is primarily responsible for the degradation of catecholamines?
Which enzymatic pathway is primarily responsible for the degradation of catecholamines?
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What is a common effect of excess catecholamines produced by pheochromocytoma?
What is a common effect of excess catecholamines produced by pheochromocytoma?
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What distinguishes the soluble form of COMT from the membrane-bound form?
What distinguishes the soluble form of COMT from the membrane-bound form?
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Study Notes
Neurotransmitters
- Neurotransmitters are chemicals that transmit signals across a synapse from one neuron to another 'target' cell.
- Catecholamines are neurotransmitters derived from the amino acid tyrosine.
- Norepinephrine (NE), epinephrine (E), and dopamine are catecholamines.
- Norepinephrine (NE) is the major neurotransmitter in the sympathetic nervous system.
- Epinephrine is more active than norepinephrine on the heart and lungs, and redirects blood flow from skin to skeletal muscles.
- In response to epinephrine, extra glucose is delivered to muscles; the heart and lungs work harder to pump oxygen, and the body prepares to run or defend itself.
Catecholamines
- Catecholamines are derivatives of catechol with an amino group as a side chain.
- Catechol is a dihydroxyphenol with two adjacent hydroxyl groups.
- Norepinephrine, epinephrine, and dopamine are all derived from the amino acid tyrosine.
- These compounds are also known as biogenic amines.
Norepinephrine
- Major transmitter in the sympathetic nervous system, transmitting signals from the spinal cord to ganglia.
- Norepinephrine is released at the postganglionic nerves.
- Stimulation of these nerves is responsible for the "flight or fight" response, including heart rate increase, sweating, and skin and bronchodilation.
- Norepinephrine-containing neurons arise from the locus ceruleus in the brainstem and are distributed across the cortex.
Epinephrine
- Epinephrine is more active than norepinephrine in the sympathetic nervous system, particularly influencing the heart and lungs.
- Redirecting blood flow from skin to skeletal muscle is another significant function.
- Epinephrine stimulates glycogen metabolism in the liver to release glucose.
Dopamine
- Dopamine is a neurotransmitter that plays a key role in voluntary movement control and is also involved in emotional responses and memory.
- Dopamine-containing nerves run in well-defined tracts, one of the most important being the nigrostriatal system, which connects the substantia nigra with basal ganglia.
- Damage to the dopamine-producing pathways can lead to Parkinson's disease.
- Dopamine causes vasodilation.
- Catabolism of dopamine produces homovanillic acid (HVA).
Glutamate
- The most important excitatory neurotransmitter in the central nervous system (CNS).
- Glutamate acts on both ionotropic and metabotropic receptors.
- An example of an ionotropic glutamate receptor is the N-methyl-D-aspartate (NMDA) glutamate receptor.
GABA
- GABA (gamma-aminobutyric acid) is a major inhibitory neurotransmitter in the brain.
- It's synthesized from glutamate.
- GABA acts on two known receptors, GABAA (ionotropic) and GABAB (metabotropic).
- GABAA receptors consist of five subunits from several gene families, resulting in diverse binding properties.
- Psychoactive drugs, like benzodiazepines, enhance GABA's effects by binding to GABAA receptors, increasing the frequency of chloride ion channel opening and hyperpolarizing the membrane.
Serotonin
- Serotonin (5-hydroxytryptamine) is an important neurotransmitter derived from tryptophan.
- Serotoninergic neurons are concentrated in the raphe nuclei of the upper brain stem and project to the cerebral cortex and spinal cord.
- Serotonin is involved in mood regulation, memory processing, sleep control, and is responsive to sensory input.
- Serotonin also affects the peripheral nervous system, controlling gastrointestinal function among other roles.
- Excessive serotonin may cause panic attacks.
Histamine
- Histamine plays roles in pain threshold, sexual arousal, pituitary hormone secretion, and blood pressure control.
- Catabolized to N-methylimidazoleacetic acid or imidazoleacetic acid, via diamine oxidase (DAO), histamine N-methyltransferase (HNMT), and aldehyde dehydrogenase.
- This process requires vitamin B6.
Glycine
- Glycine is an inhibitory neurotransmitter in the spinal cord, with an action comparable to GABA in the brain, resulting in hyperpolarization.
- It is packed in vesicles and released via exocytosis.
- Glycine receptor structure resembles the GABAA receptor, and its primary effect involves opening chloride channels.
Nitric Oxide Gas
- Produced by synaptic terminals that innervate smooth muscle in blood vessels and at the synapses in regions of the brain.
- Also called endothelium-derived relaxing factor (EDRF).
- Causes vasodilation.
Neuropeptides
- Synthesized in neuron bodies like other proteins.
- Undergoes modifications after synthesis, affected by prohormone action, convertases, and carboxypeptidases.
- The processed products (neuropeptides) are transported to the presynaptic region.
- Neuropeptides play diverse roles in regulating pain, pituitary function, digestive reflexes, appetite, and behavioral effects.
Neuromodulators
- Neuromodulators alter the rate of neurotransmitter release from presynaptic neurons or alter the postsynaptic response to neurotransmitters.
- Neuropeptides can be classified as neuromodulators.
- Neuromodulators act by binding to receptors on pre- and postsynaptic membranes and activating cytoplasmic enzymes.
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Description
This quiz explores the role of neurotransmitters in the limbic system, particularly focusing on dopamine and glutamate. It includes questions about their functions, connections to various physiological conditions, and implications for neurodegenerative processes. Test your knowledge on these critical components of the brain's chemistry.
