L4- ANS

Question 1

Where are the sympathetic ganglia?

Answer 1

Near the spinal cord

-short pre-ganglionic neuron, long post-ganglionic neuron

Question 2

Where are the parasympathetic ganglia?

Answer 2

Near the effector organ

-long pre-ganglionic neuron, short post-ganglionic neuron

Question 3

Why is the adrenal medulla like a post-ganglionic sympathetic neuron?

Answer 3

The adrenal medulla makes and releases epinephrine and norepinephrine into the bloodstream directly to stimulate response

• Post-ganglionic sympathetic neurons also release NE

Question 4

What are the neurotransmitters used by the parasympathetic and sympathetic neurons, both pre- and post-ganglia?

Answer 4

Parasympathetic:

Pre-Ganglia: ACh

Post-Ganglionic: ACh

Sympathetic:

Pre-Ganglia: ACh

Post-ganglionic: NE (and FEW Ach)

All ANS pre-ganglia neurons release Acetylcholine (ACh)

Question 5

What receptors are typically found on parasympathetic end organs?

Answer 5

Muscarinic Receptors (Slow)

Question 6

What TYPE of the receptor is used by the parasympathetic end organs?

Answer 6

G protein Coupled Receptor (GPCR)
-Metabotropic

Question 7

What receptors are typically found on sympathetic end organs?

Answer 7

Adrenergic Receptors (Fast)

1. Alpha-Adrenergic

• α1: Activate phospholipase C -> produces IP3 and diacylglycerol (EXCITATORY)
• α2: Inhibit Adenylyl Cyclase -> decrease cAMP formation (INHIBITORY)

2. Beta-Adrenergic (Stimulates adenylyl cyclase: EXCITATORY)

• β1: Inc cardiac rate and force
• β2: Bronchodilation, Vasodilation, relaxation of visceral muscles, muscle tremor
• β3: lipolysis, thermogenesis

Weird exception:

Sweat glands have muscarinic receptors on sympathetic ends

Question 8

What TYPE of receptor is used by the sympathetic end organs?

Answer 8

G protein Coupled Receptor (GPCR)
-Metabotropic

Question 9

Where are the receptors that are inhibitory to neurotransmitter released?

Answer 9

ACh inhibitory receptors:

M2, M4 from presynaptic terminal

NE inhibitory receptors:

α2 from postsynaptic terminal

Question 10

What limits the rates of synthesis of ACh?

Answer 10

Access to Choline/Amount of Choline in the presynaptic terminal

• Choline is charged and most require transporter to cross membrane. Synthesis of acetylcholine depends on availability of Choline inside cell

Question 11

What limits the rate of synthesis of NE?

Answer 11

The Hydroxylation tyrosine to form Dopa by Enzyme Tyrosine hydroxylase (tetrahydrobiopterin)

• Enzyme occurs in only catecholaminergic neurons

Question 12

What process terminates the action of ACh?

Answer 12

Hydrolysis of ACh via Acetylcholinesterase

Question 13

What process terminates the action of NE?

Answer 13

Reuptake of nonrepinephrine to the presynaptic vesicle

• Is target for many first generation drugs

Question 14

What is Atropine?

Answer 14

Drug that blocks all muscarinic receptors

Question 15

What is Propranolol?

Answer 15

Drug that blocks all beta-adrenergic receptors

Question 16

*The transmitter used by postganglionic autonomic neurons and the receptor on which transmitter released from these neurons acts are

a. Norepinephrine/alpha1-adrenergic receptors
b. Norepinephrine/beta-adrenergic receptors
c. Acetylcholine/muscarinic receptors
d. Acetylcholine/nicotinic receptors
e. They are different depending on whether it is sympathetic or parasympathetic

Answer 16

e. They are different depending on whether it is sympathetic or parasympathetic

Question 17

*The transmitter used by preganglionic autonomic neurons and the receptor on which transmitter released from these neurons acts are

a. Norepinephrine/alpha1-adrenergic receptors
b. Norepinephrine/beta-adrenergic receptors
c. Acetylcholine/muscarinic receptors
d. Acetylcholine/nicotinic receptors
e. They are different depending on whether it is sympathetic or parasympathetic

Answer 17

d. Acetylcholine/nicotinic receptors

Question 18

*What is the rate-limiting step in the synthesis of acetylcholine?

a. The enzyme tyrosine hydroxylase
b. The production of acetyl-coenzyme A (acetyl-CoA)
c. The update of acetylcholine into the presynaptic neuron
d. The enzyme choline acetyltransferase
e. The uptake of choline

Answer 18

e. The uptake of choline

Question 19

*The adrenal medulla is like a

a. Preganglionic sympathetic neuron
b. Postganglionic sympathetic neuron
c. Preganglionic parasympathetic neuron
d. Postganglionic parasympathetic neuron
e. All of the above

Answer 19

b. Postganglionic sympathetic neuron

Question 20

Which receptors mediate neurotransmission in the autonomic ganglia?
A. alpha-adrenergic
B. beta-adrenergic
C. nicotinic-cholinergic
D. muscarinic-cholinergic
E. None of the above

Answer 20

C. nicotinic-cholinergic

Question 21

What is the transmitter usually found in post-ganglionic sympathetic nerves?
A. norepinephrine
B. acetylcholine
C. nitric oxide
D. epinephrine
E. none of the above

Answer 21

A. norepinephrine

Question 22

What is the limiting factor in the synthesis of acetylcholine?
A. the activity of tyrosine hydroxylase
B. the concentration of acetyl-CoA
C. the amount of choline in the presynaptic terminal
D. m2 muscarinic receptor stimulation

Answer 22

C. the amount of choline in the presynaptic terminal

Question 23

What is the rate-limiting step in the synthesis of norepinephrine?
A. The uptake of tyrosine into the neuron
B. The hydroxylation of tyrosine to form DOPA
C. the decarboxylation of DOPA to form dopamine
D. the hydroxylation of dopamine to form norepinephrine
E. none of the above

Answer 23

B. The hydroxylation of tyrosine to form DOPA

Question 24

A drug that stimulates beta 1 and beta 2-adrenoceptors can be expected to cause:

a. A decrease in heart rate
b. A decrease in total peripheral resistance
c. A constriction of airway smooth muscle resistance
d. A decrease in renin release

Answer 24

b. A decrease in total peripheral resistance

Question 25

What is the rate-limiting step in the synthesis of epinephrine?

a. Conversion of dopa to dopamine by aromatic L-amino acid decarboxylase
b. Conversion of norepinephrine to epinephrine by

phenylethanolamine-N-methyltransferase

c. Conversion of tyrosine to dopa by tyrosine hydroxylase
d. Conversion of dopamine to norepinephrine by dopamine beta-hydroxylase
e. None of the above

Answer 25

c. Conversion of tyrosine to dopa by tyrosine hydroxylase

Question 26

The primary neurotransmitter released by postganglionic neurons of the autonomic sympathetic system:

a. Epinephrine
b. Dopamine
c. Dobutamine
d. Norepinephrine
e. Phenylephrine

Answer 26

d. Norepinephrine

Question 27

In the autonomic nervous system, which receptors are considered (give examples):

1. ) Fast
2. ) Slow

Answer 27

1. FAST: Ligand Gated Ion Channels

Ex: Nicotinic (ACh)

2. SLOW: Metabotrpic Receptors

Ex: Muscarinic (ACh); Adrenergic (NE, EPI)