Norepinephrine Synthesis & Release Flashcards
Select the true statements regarding norepinephrine synthesis and release.
(Select 2.)
I need help!!!!
—– is the primary neurotransmitter in the sympathetic nervous system
Norepinephrine
You should understand how NE is synthesized, released, removed from the synaptic cleft, and metabolized. We will cover synthesis and release here.
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Sympathetic neurons synthesize NE from
—– or —–.
Tyrosine, or
Phenylalanine
Tyrosine is an —– obtained from diet
Amino acid
Prior to being used for NE synthesis, Phenylalanine is first converted to —–.
Tyrosine
Tyrosine is transported into the nerve terminal of which type of nerves?
Adrenergic nerves
Tyrosine is transported into the adrenergic nerve terminal and converted into —–
DOPA
Tyrosine is transported into the adrenergic nerve terminal and converted into DOPA by the enzyme —–
Tyrosine hydroxylase
Tyrosine is transported into the adrenergic nerve terminal and converted into DOPA by the enzyme tyrosine hydroxylase. This occurs in the —–
Cytoplasm
Tyrosine is transported into the adrenergic nerve terminal and converted into DOPA by the enzyme tyrosine hydroxylase. This occurs in which step of norepinephrine synthesis?
Rate-limiting step
DOPA is converted to —–
Dopamine
DOPA is converted to dopamine by the enzyme —–.
DOPA decarboxylase
DOPA is converted to dopamine by the enzyme DOPA decarboxylase. This also occurs in the —–.
Cytoplasm
Dopamine is transported into a —– vesicle
synaptic vesicle
Dopamine is transported into a synaptic vesicle and is converted to —–.
Norepinephrine
Dopamine is transported into a synaptic vesicle and is converted to norepinephrine by the enzyme —–.
Dopamine beta-hydroxylase
In the adrenal medulla, most of the norepinephrine is converted to —–.
Epinephrine
In the adrenal medulla, most of the norepinephrine is converted to epinephrine by the enzyme —–.
Phenyl-ethanolamine-N-methyl-transferase
The adrenal medulla secretes about —–% epinephrine and —–% norepinephrine into the circulation
80% epinephrine (Epi), and
20% norepinephrine (NE)
How is Norepinephrine released?
The —– depolarizes the nerve terminal
Action potential
How is Norepinephrine released?
The action potential depolarizes the nerve terminal. —– channels open.
Voltage-gated calcium channels
How is Norepinephrine released?
The action potential depolarizes the nerve terminal. Voltage-gated calcium channels open, and calcium flows —– the nerve terminal.
flows into the nerve terminal.
How is Norepinephrine released?
Increased neuronal calcium causes —– to fuse with the nerve terminal
NE vesicles
How is Norepinephrine released?
Increased neuronal calcium causes NE vesicles to fuse with the nerve terminal and release NE into the —–.
Synaptic cleft
How is Norepinephrine released?
Increased neuronal calcium causes NE vesicles to fuse with the nerve terminal and release NE into the synaptic cleft via —–.
Exocytosis
NE inhibits its release by stimulating the —–receptor
pre-synaptic alpha-2 receptor
NE can augment its release by stimulating the —– receptor.
pre-synaptic beta-2 receptor
Select the true statements regarding norepinephrine synthesis and release. (Select 2.)
Correct Answer:
- Tyrosine hydroxylase catalyzes the rate-limiting step in norepinephrine synthesis.
- Norepinephrine in the synaptic cleft inhibits its own release
Norepinephrine is converted to epinephrine in the —–.
Adrenal medulla
(Not in sympathetic post-ganglionic nerves).
The adrenal medulla releases —–% epinephrine and —–% norepinephrine
80% epinephrine and 20% norepinephrine
(the answer choice was reversed)
Be aware of this trick!!!!!
References**:
- Barash. Clinical Anesthesia. 8th ed. 201* 7. p. 341.
- Hemming* s. Pharmacology and Physiology for Anesthesia: Foundations and Clinical Application. 1st ed. 2013. p. 212 & 22 1-222. Flood. Stoelting’s Pharmacology & Physiology in Anesthetic Practice. 5th ed**. 2015. p. 82-84.
