Norepinephrine Synthesis & Release

Question 1

Select the true statements regarding norepinephrine synthesis and release.

(Select 2.)

Answer 1

I need help!!!!

Question 2

—– is the primary neurotransmitter in the sympathetic nervous system

Answer 2

Norepinephrine

Question 3

You should understand how NE is synthesized, released, removed from the synaptic cleft, and metabolized. We will cover synthesis and release here.

Answer 3

Thanks, God!

Question 4

Sympathetic neurons synthesize NE from

—– or —–.

Answer 4

Tyrosine, or

Phenylalanine

Question 5

Tyrosine is an —– obtained from diet

Answer 5

Amino acid

Question 6

Prior to being used for NE synthesis, Phenylalanine is first converted to —–.

Answer 6

Tyrosine

Question 7

Tyrosine is transported into the nerve terminal of which type of nerves?

Answer 7

Adrenergic nerves

Question 8

Tyrosine is transported into the adrenergic nerve terminal and converted into —–

Answer 8

DOPA

Question 9

Tyrosine is transported into the adrenergic nerve terminal and converted into DOPA by the enzyme —–

Answer 9

Tyrosine hydroxylase

Question 10

Tyrosine is transported into the adrenergic nerve terminal and converted into DOPA by the enzyme tyrosine hydroxylase. This occurs in the —–

Answer 10

Cytoplasm

Question 11

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?

Answer 11

Rate-limiting step

Question 12

DOPA is converted to —–

Answer 12

Dopamine

Question 13

DOPA is converted to dopamine by the enzyme —–.

Answer 13

DOPA decarboxylase

Question 14

DOPA is converted to dopamine by the enzyme DOPA decarboxylase. This also occurs in the —–.

Answer 14

Cytoplasm

Question 15

Dopamine is transported into a —– vesicle

Answer 15

synaptic vesicle

Question 16

Dopamine is transported into a synaptic vesicle and is converted to —–.

Answer 16

Norepinephrine

Question 17

Dopamine is transported into a synaptic vesicle and is converted to norepinephrine by the enzyme —–.

Answer 17

Dopamine beta-hydroxylase

Question 18

In the adrenal medulla, most of the norepinephrine is converted to —–.

Answer 18

Epinephrine

Question 19

In the adrenal medulla, most of the norepinephrine is converted to epinephrine by the enzyme —–.

Answer 19

Phenyl-ethanolamine-N-methyl-transferase

Question 20

The adrenal medulla secretes about —–% epinephrine and —–% norepinephrine into the circulation

Answer 20

80% epinephrine (Epi), and

20% norepinephrine (NE)

Question 21

How is Norepinephrine released?

The —– depolarizes the nerve terminal

Answer 21

Action potential

Question 22

How is Norepinephrine released?

The action potential depolarizes the nerve terminal. —– channels open.

Answer 22

Voltage-gated calcium channels

Question 23

How is Norepinephrine released?

The action potential depolarizes the nerve terminal. Voltage-gated calcium channels open, and calcium flows —– the nerve terminal.

Answer 23

flows into the nerve terminal.

Question 24

How is Norepinephrine released?

Increased neuronal calcium causes —– to fuse with the nerve terminal

Answer 24

NE vesicles

Question 25

How is Norepinephrine released?

Increased neuronal calcium causes NE vesicles to fuse with the nerve terminal and release NE into the —–.

Answer 25

Synaptic cleft

Question 26

How is Norepinephrine released?

Increased neuronal calcium causes NE vesicles to fuse with the nerve terminal and release NE into the synaptic cleft via —–.

Answer 26

Exocytosis

Question 27

NE inhibits its release by stimulating the —–receptor

Answer 27

pre-synaptic alpha-2 receptor

Question 28

NE can augment its release by stimulating the —– receptor.

Answer 28

pre-synaptic beta-2 receptor

Question 29

Select the true statements regarding norepinephrine synthesis and release. (Select 2.)

Answer 29

Correct Answer:

1. Tyrosine hydroxylase catalyzes the rate-limiting step in norepinephrine synthesis.
2. Norepinephrine in the synaptic cleft inhibits its own release

Question 30

Norepinephrine is converted to epinephrine in the —–.

Answer 30

Adrenal medulla

(Not in sympathetic post-ganglionic nerves).

Question 31

The adrenal medulla releases —–% epinephrine and —–% norepinephrine

Answer 31

80% epinephrine and 20% norepinephrine

(the answer choice was reversed)

Be aware of this trick!!!!!

Question 32

References**:

Answer 32

• 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.