ANS Medications

Question 1

What are the two major neurotansmitters for the ANS?

Answer 1

Acetylcholine (ACh)

Noradrenaline (NAd)

Question 2

What are the two main types of acetylcholine receptors and the two main types of

Answer 2

Acetylcholine = Nicotinic and Muscarinic

Adrenoreceptors - Alpha and Beta

Question 3

What are the key characteristics of nicotinic acetylcholine receptors (nAChRs)?

Answer 3

nAChRs are expressed on:

• Parasympathetic and sympathetic ganglion cells
• Adrenal medullary cells
• Skeletal muscle cells
• Neurons in the CNS

nAChRs are all:

• Ligand-gated ion channels
• Composed of five subunits
• Excitatory

Question 4

What are the key characteristics of muscarinic acetycholine receptors (mAChRs)?

Answer 4

mAChRs are expressed on:

• The heart, eyes, salivary glands, gastrointestinal nerves, and respiratory smooth muscle cells when innervated by parasympathetic postganglionic nerve fibres
• Sweat glands when innervated by sympathetic postganglionic nerve fibres
• A few autonomic ganglion cells
• Neurons in the CNS

mAChRs are all:

• G-protein coupled receptors
• Excitatory and inhibitory

Question 5

What are the 5 subtypes of muscarinic acetylcholine receptors and what are their functions?

Answer 5

M1 = Stimulates salivary and gastric acid secretion
M2 = Slows heart rate and contractility
M3 = Contracts smooth muscle in GIT and respiratory tract, constricts eye pupils
M4 = Inhibits neurons in CNS
M5 = Excites neurons in CNS

Question 6

What are the nicotinic effects of ACh and AChRs?

Answer 6

Stimulation of postganglionic fibres (symp + parasymp) = increased neurotransmission
Contraction of skeletal muscle
Release of adrenaline and noredrenaline from adrenal medulla
Central nervous system excitation

Question 7

What are the muscarinic effects of ACh at AChRs?

Answer 7

Smooth muscle contraction = pupil miosis, increases GI and urinary motility, airway construction

Secretions = increased salivary and airway secretions

Smooth muscle relaxation = vasodilation (decrease in rate and force of heart)

Question 8

What are the effects of adrenaline / noradrenaline on the different subtypes of adrenoreceptors?

Answer 8

All adrenergic receptors are G-protein coupled receptors

Alpha 1 = vasoconstriction
Alpha 2 = Inhibition of transmitter release
Beta 1 = Increase rate and force of heart contractions
Beta 2 = Vasodilation, relaxation of smooth muscle
Beta 3 = Relaxation fo bladder smooth muscle

Question 9

What ar ethe 4 different types of ANS medications?

Answer 9

Cholinergic agonists
Cholinergic antagonists / anticholinergics
Adrenergic agonists
Adrenergic antagonists

Question 10

What are cholinergic and anticholinergic drugs?

Answer 10

These are drugs that resemble the molecular structure of ACh
They include ACh receptor agonists and antagonists
They target muscarinic ACh receptors and nicotinic ACh receptors OR the enzyme that breaks down ACh

Question 11

What are 2 cholinergic medications and their uses?

Answer 11

Pilocarpine = mAChR agonist, treats xerostomia

Neostigmine = Acetylcholinesterase inhibitor, reverses neuromuscular blockades in general anaesthesia

Question 12

What are two anycholinergic medications and their uses?

Answer 12

Atropine = Non-selective mAChR antagonist, used to manage bradycardia in GA

Glycopyrrolate = Non-selective mAChR antagonist, used as an anti-sialagogue

Question 13

What are 3 examples of adrenergic agonists and their uses?

Answer 13

Phenlyephrine = decongestant
Salbutameol = treats asthma and chronic obstructive pulmonary
Adrenaline = used with LA to delay absorption and increase duration but can also be used in the emergency treatment of anaphylaxis

Question 14

What are 2 examples of adrenergic antagonists?

Answer 14

Prazosin = treats benign prostatic hypertrophy

Atenolol = treats angina, reduces heart rate