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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}} {{Alison}}
|QuestionAuthor={{Rim}}
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Biochemistry
|MainCategory=Biochemistry
Line 20: Line 20:
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|SubCategory=Neurology
|SubCategory=Neurology
|Prompt=A researcher investigating the regulatory neurotransmitters in the basal ganglia sends high frequency electrical impulses into specific areas of the brain of a rat and measures the change in the local concentration of several neurotransmitters. Upon stimulation of the caudate, the researcher observes an increase in the release of a neurotransmitter known to inhibit the globus pallidus internus. Which of the following amino acids is the released neurotransmitter derived from?
|Prompt=A researcher is investigating the regulatory neurotransmitters in the basal ganglia.  In his experiment, the researcher sends high frequency electrical impulses into specific areas of the brain of a rat and measures the change in the local concentration of several neurotransmitters. Upon stimulation of the caudate, an increase in the release of a neurotransmitter is detected.  The released neurotransmitter is known to inhibit the globus pallidus internus. Which amino acid is the released neurotransmitter derived from?
|Explanation=The [[caudate nucleus]] is involved in the direct and indirect pathways of the fine tuning of motor activity. The [[caudate nucleus]] is physiologically stimulated by [[glutamate]] released from the motor cortex.  Stimulation of the [[caudate nucleus]], physiologically or experimentally, will likely lead to the release of [[GABA|gamma-aminobutyric acid (GABA)]]. [[GABA]] is an inhibitory neurotransmitter derived from [[glutamate]].  The synthesis of [[GABA]] requires [[vitamin B6]].
|Explanation=The [[caudate]] is involved in the direct and indirect pathways of the fine tuning of motor activity. The caudate is physiologically stimulated by [[glutamate]] released from the motor cortex.  Stimulation of the caudate, physiologically or experimentally, will likely lead to the release of [[GABA]]. GABA is an inhibitory neurotransmitter derived from [[glutamate]].  The synthesis of GABA requires [[vitamin B6]].


|EducationalObjectives= [[GABA]] is synthesized from [[glutamate]] using the enzyme L-glutamic acid decarboxylase and [[pyridoxal phosphate|pyridoxal phosphate (vitamin B6)]] as a cofactor.
Education objective:
|References= First Aid 2014 page 110


[[GABA]] is derived from [[glutamate]].
|AnswerA=Tryptophan
|AnswerA=Tryptophan
|AnswerAExp=[[Tryptophan]] is not a precursor for [[GABA]].
|AnswerAExp=[[Tryptophan]] is not a precursor for GABA.
|AnswerB=Glycine
|AnswerB=Glycine
|AnswerBExp=[[Glycine]] is not a precursor for [[GABA]].
|AnswerBExp=[[Glycine]] is not a precursor for GABA.
|AnswerC=Glutamate
|AnswerC=Glutamate
|AnswerCExp=[[Glutamate]] is the precursor for [[GABA]], the synthesis of which requires vitamin B6.
|AnswerCExp=Glutamate is the precursor for GABA, the synthesis of which requires vitamin B6.
|AnswerD=Arginine
|AnswerD=Arginine
|AnswerDExp=[[Arginine]] is not a precursor for [[GABA]].
|AnswerDExp=[[Arginine]] is not a precursor for GABA.
|AnswerE=Lysine
|AnswerE=Lysine
|AnswerEExp=[[Lysine]] is not a precursor for [[GABA]].
|AnswerEExp=[[Lysine]] is not a precursor for GABA.
|RightAnswer=C
|RightAnswer=C
|WBRKeyword=Basal ganglia, [[GABA]], glycine
|WBRKeyword=Basal ganglia, GABA, glycine
|Approved=No
|Approved=No
}}
}}

Revision as of 19:22, 7 October 2014
Author [[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Biochemistry
Sub Category SubCategory::Neurology
Prompt [[Prompt::A researcher is investigating the regulatory neurotransmitters in the basal ganglia. In his experiment, the researcher sends high frequency electrical impulses into specific areas of the brain of a rat and measures the change in the local concentration of several neurotransmitters. Upon stimulation of the caudate, an increase in the release of a neurotransmitter is detected. The released neurotransmitter is known to inhibit the globus pallidus internus. Which amino acid is the released neurotransmitter derived from?]]
Answer A AnswerA::Tryptophan
Answer A Explanation [[AnswerAExp::Tryptophan is not a precursor for GABA.]]
Answer B AnswerB::Glycine
Answer B Explanation [[AnswerBExp::Glycine is not a precursor for GABA.]]
Answer C AnswerC::Glutamate
Answer C Explanation AnswerCExp::Glutamate is the precursor for GABA, the synthesis of which requires vitamin B6.
Answer D AnswerD::Arginine
Answer D Explanation [[AnswerDExp::Arginine is not a precursor for GABA.]]
Answer E AnswerE::Lysine
Answer E Explanation [[AnswerEExp::Lysine is not a precursor for GABA.]]
Right Answer RightAnswer::C
Explanation [[Explanation::The caudate is involved in the direct and indirect pathways of the fine tuning of motor activity. The caudate is physiologically stimulated by glutamate released from the motor cortex. Stimulation of the caudate, physiologically or experimentally, will likely lead to the release of GABA. GABA is an inhibitory neurotransmitter derived from glutamate. The synthesis of GABA requires vitamin B6.

Education objective:

GABA is derived from glutamate.
Educational Objective:
References: ]]

Approved Approved::No
Keyword WBRKeyword::Basal ganglia, WBRKeyword::GABA, WBRKeyword::glycine
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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