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Autonomic Nervous System (Pharmacology) Flashcards

1
Q

Match.
Afferent vs Efferent
Away vs Toward CNS

A

Afferent - Toward CNS

Efferent - Away from CNS

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2
Q

What are the 3 components of the ANS (Motor & Sensory)?

A

Sympathetic NS
Parasympathetic NS
Enteric NS

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3
Q

Motor ANS mediates output from CNS to whole body except?

A

Voluntary skeletal muscles (Under SOMATIC efferent)

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4
Q

Which exocrine secretion(s) is under ANS control?

A

All

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5
Q

Which common disease is associated with ANS dysfunction?

A

Diabetes

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6
Q

Match.
Fight/Flight vs Rest/Digest
Sympathetic vs Parasympathetic

A

Sympathetic NS - Fight/Flight functions

Parasympathetic NS - Rest & Digest

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7
Q

Outflow tract of SNS and PNS?

A

SNS - Thoracolumbar (Spinal cord)

PNS - Craniosacral (Brain stem and spinal cord)

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8
Q

What is the preganglionic length of SNS and PNS and where do they synapse?

A

SNS - Short. Synapses in pre/para-vetebral ganglia; branches extensively to synapse with postganglionic neurons –> effectors

PNS - Long. Synapse in terminal ganglia usually at walls of effector organs.

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9
Q

What is the postganglionic length of SNS and PNS

A

SNS - Long.

PNS - Short.

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10
Q

What are the pre and postganglionic neurotransmitters of SNS and PNS?

A

SNS: Pre (ACh), Post (Noradrenaline)
PNS: Pre (ACh), Post (ACh)

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11
Q

Appearance of preganglionic fibers of SNS and PNS?

A

White. Both myelinated (Motor B-fibres)

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12
Q

Appearance of postganglionic fibers of SNS and PNS?

A

Grey. Both largely un-myelinated (Motor C-fibres)

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13
Q

How is ACh released at the preganglionic neuron?

A

Voltage-gated calcium selective channel opens due to AP from CNS –> Ca2+ influx –> ACh released via exocytosis

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14
Q

Where does ACh bind to after release from the preganglionic neuron?

A

Binds to ligand-gated ion channels (Nicotinic ACh receptors) in postganglionic neuron resulting in AP –> Ca2+ influx –> Noradrenaline release to activate GPCR adrenoceptors in effector cell

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15
Q

What does ACh released at the postganglionic neuron bind to?

A

GPCR muscarinic ACh receptors in effector cell

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16
Q

What are the non-adrenergic, non-cholinergic (NANC) transmitters co-released alongside NA or ACh at the postganglionic fibres for SNS and PNS respectively?

A

SNS: ATP > NA > Neuropeptide Y
PNS: ACh > NO > VIP

**Speed of response from rapid & short-lived to slow & sustained

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17
Q

Are the Nicotinic ACh receptors the same as Nicotinic receptors found in neuromuscular junctions or CNS?

A

No

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18
Q

What are the 2 types of cholinoceptors?

A
  1. Nicotinic ACh receptor (LGIC)

2. Muscarinic ACh receptor (GPCR)

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19
Q

What is the type of all adrenoceptors?

A

GPCR

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20
Q

Rank potency of agonists on a and B adrenoceptors.

Noradrenaline, Adrenaline, Isoprenaline

A

a-adrenoceptor: Noradrenaline > Adrenaline > Isoprenaline

B-adrenoceptor: Isoprenaline > Adrenaline > Noradrenaline

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21
Q

What is found at the sympathetic chain?

A

Paravertebral ganglia (Synapse of pre- and post-ganglions)

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22
Q

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

A

Uptake of choline via CHT transporter

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23
Q

What are the 2 enzymes involved in ACh synthesis?

A 
Choline acetyltransferase (ChAT)
Acetyl CoA
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24
Q

What causes exocytosis of vesicles containing ACh , ATP and anions?

A

AP via calcium influx from Voltage gated calcium channels

25
What happens to ACh as it binds to ACh receptors and invoke a cellular response? (2)
At the same time, it is 1. Degraded by acetylcholinesterase (AChE) to choline and acetate 2. Re-uptake and reuse of choline
26
How many preganglionic neurones can synapse with a postganglionic neuron?
Several
27
What does graded depolarisation or excitatory post-synaptic potential (epsp) depend on?
Number of nicotinic ACh receptors activated to reach threshold for AP to be initiated (opens voltage-gated Na+ channel)
28
What are the 3 sites that are predominantly sympathetic?
Arterioles, veins, sweat glands
29
What is mydriasis? Does the blockage of SNS or PNS cause this?
Pupil dilation | PNS (Predominant tone of Iris)
30
What does blocking of PNS (Predominant tone) to the ciliary muscles of the eye result in?
Cycloplegia (Unable to contract thus cannot accommodate vision to view nearby objects)
31
Why does atropine inhibit sweating?
Blocks M3 ACh receptor
32
Does blocking cholinergic transmission at the ganglia block SNS or PNS?
Both
33
What is an example of a non-depolarising competitive and non-competitive antagonist for cholinergic transmission at the ganglia?
Competitive - Trimethaphan | Non-competitive - Hexamethonium (Open channel blocker by reversibly plugging the channel)
34
What can high concentration of agonist (E.g. Nicotine) result in at the cholinergic ganglia?
Depolarisation block due to desensitisation from prolonged depolarisation
35
How many neuroeffector junctions are there along an axon at the parasympathetic division?
Several
36
What happens after ACh is degraded or reuptaken?
Transmission stops
37
What are the 4 receptors with Gq a-subunit?
a1: smooth muscle contraction, ejaculation M1: Acid secretion M3: Airway contraction, NO release (relaxes vascular smooth muscles ONLY in penis (erection), pancreas and salivary glands), Stimulates mucus production, Increases intestinal motility and secretion, contracts detrusor muscle of bladder M5
38
What are the 3 receptors with Gi a-subunit?
a2 - inhibits noradrenaline release M2: Opens K+ channels, decreases HR and ATRIA force M4
39
What are the 2 receptors with Gs a-subunit?
B1: Increases HR and cardiac force B2: Relaxes bronchi and skeletal smooth muscles, decreases mucus production **1 heart, 2 lungs
40
What happens to the mouth if the PNS is blocked?
Xerostomia as salivary glands are predominantly modulated by PNS
41
What happens to the urinary bladder if the PNS is stimulated?
Micturition as PNS is the predominant tone
42
What is the precursor for synthesizing noradrenaline?
Dopamine (from L-tyrosine)
43
Which VGIC has to be activated by depolarising AP for vesicles containing noradrenaline to be exocytosed?
Calcium
44
What happens to noradrenaline after it binds to adrenoceptors? (2)
Re-uptake - by U1 in post-ganglionic neurone - by U2 in neighboring neurons or effector cells Metabolised - by monoamine oxidase (MAO) in post-ganglionic neurone - by catechol-O-methyltransferase (CoMT) in effector cells
45
What regulates the release of transmitter by presynaptic neurons to prevent overstimulation?
Pre-synaptic autoreceptors via negative feedback | - agonist activate autoreceptors which inhibits calcium channel activation thus no exocytosis of ACh or NA
46
What is the drug that blocks U1, allowing NA to accumulate in the synaptic cleft to increase stimulation? What does this result in? (2)
Cocaine a1- vasoconstriction, B1- arrhythmias
47
What is the mechanism of action of amphetamine?
Substrate of U1 Enters noradrenergic terminal and inhibits MAO Enters synaptic vesicle to displace NA into cytoplasm NA exits into the synaptic cleft via U1 (reverse)
48
What is a selective, competitive antagonist of a1?
Prazosin
49
What is a selective, competitive antagonist of B1?
Atenolol
50
What is a selective agonist of B2?
Salbutamol
51
What is a non-selective, competitive antagonist for all muscarinic ACh receptors? What is it used for? (2)
Atropine. | For bradycardia after MI and anti-cholinesterase poisoning
52
Does atropine block nicotinic ACh receptors?
No
53
What are the receptors involved in SNS and PNS of the heart?
SNS: B1 PNS: M3
54
What are the receptors involved in SNS and PNS of the lung?
SNS: B2 PNS: M3
55
What are the receptors (3) involved in GI sphincter constriction and reducing GI motility? What receptor is involved in the reverse?
SNS: a1, a2, B2 PNS: M3
56
What effect does PNS have on the vasculature?
Very minimal, only causes relaxation in some areas
57
What are the receptors involved in SNS and PNS of the adrenal medulla?
SNS: Nicotinic AChR due to pre-ganglionic innervation --> release of adrenaline and NA PNS: No effect
58
What are the receptors (3) involved in detrusor muscle relaxation of bladder and internal urinary sphincter constriction? What receptor is involved in the reverse?
Detrusor muscle - SNS (B2, B3) - PNS (M3) Internal urinary sphincter - SNS (a1) - PNS (NO)

Principles (14 decks)

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