Cholinergic Pharmacology

Question 1

What does afferent mean

Answer 1

Carries signal toward the brain or spinal cord

Question 2

What does efferent mean

Answer 2

Carries signal away from the brain or spinal cord

Question 3

Adrenergic definition

Answer 3

relating to adrenaline or noradrenaline and their receptors

Question 4

Cholinergic definition

Answer 4

relating to acetylcholine and its receptors

Question 5

Somatic v Autonomic NS

Answer 5

Somatic - single neurone between CNS and skeletal muscle
Autonomic = two neuron chain, leads to excitation or inhibition

Question 6

Ganglionic chain structure in sympathetic system

Answer 6

The ganglion is within a chain adjacent to the spinal cord
(Short pre-ganglionic fibre, long post-ganglionic fibre)

Question 7

Ganglionic chain structure in parasympathetic system

Answer 7

The ganglion is within or very close to the effector organ - long pre-ganglionic fibre, short postganglionic fibre

Question 8

What receptors do both sympathetic and parasympathetic fibres act on the pre-ganglionic receptor

Answer 8

Ach acts on nicotinic receptor

Question 9

What receptors do the parasympathetic fibres act on the post ganglionic receptor

Answer 9

Ach on muscarinic receptors

Question 10

What receptors do the sympathetic fibres ac on the post ganglionic

Answer 10

Adrenaline on alpha beta-adrenergic receptor

Question 11

Exceptions to the receptor rule

Answer 11

Sometimes Ach is released at sympathetic postganglionic termini (e.g., sweat glands)
Nitric oxide - is released from parasympathetic postganglionic termini in blood vessels

Question 12

Cholinergic receptor examples

Answer 12

Nicotinic receptors - stimulates the sympathetic and parasympathetic nervous system
Muscarinic receptors - stimulates the parasympathetic nervous system. These M receptors are receptive to drug targeting

Question 13

Types of muscarinic receptors and where are they found

Answer 13

M1: Brain
M2: Heart - their activation slows the heart, so we can block these
M3: Lungs + All organs with parasympathetic innervation
M4: Mainly CNS
M5: Mainly CNS
All are found outside the cell and activate intracellular processes through G proteins

Question 14

How do M2 receptors work?

Answer 14

Activation of M2 on heart SA node - decreases heart rate
Activation of M2 on heart AV node - decreases conduction velocity, induces AV node block (increases PR interval)

Question 15

How do M3 receptors work?

Answer 15

Respiratory system - produces mucus (airways and nasopharynx) and induces smooth muscle contraction (bronchoconstriction)
GI tract - increases saliva production, increases gut motility, stimulates biliary secretion
Skin - only place where sympathetic systemic releases Ach. causes sweating
Urinary system - contracts detrusor muscle, relaxation of internal urethral sphincter
Eye - causes myosis, increases drainage of aqueous humour, secretion of tears

Question 16

Example of M3 agonist

Answer 16

Pilocarpine eye drops
- increases drainage of aqueous humour
- reduces ocular pressure
- treats acute (closed angle) glaucoma
- also used to treat dry mouth

Question 17

Example of M3 antagonist

Answer 17

Hyoscine - used in palliative care to treat respiratory secretions and symptoms of bowel obstruction

Question 18

Role of inhaled antimuscarinic and example

Answer 18

Bronchodilation
e.g., Tiotropium

Question 19

Side effects of inhaled antimuscarinics

Answer 19

Dry mouth,
Urinary retention
Can worsen existing glaucoma

Question 20

Other examples of antimuscarinics

Answer 20

Solifenacin - treatment for overreactive bladder = inhibits smooth muscle contraction
Meberevine - IBS - slows contractility in the gut

Question 21

ACh outside the ANS - CNS

Answer 21

ACh also used in CNS receptors and implicated in memory
- therefore anticholinergics (antimuscarinics) can cause memory problems
Antiemesis - hyoscine can be used for nausea

Question 22

ACh outside the ANS - Somatic nervous system

Answer 22

Botulinum prevents Ach release - causes flaccid paralysis and death from respiratory muscle involvement - treat painful muscle spasms or BoTox cosmetically

Question 23

Role of Nicotinic (N1) receptor blockers in somatic nervous system

Answer 23

Inhibit Ach activity
Rocuronium, suxamethonium , pancuronium = used as muscle relaxants in surgery

Question 24

What is myasthenia gravis

Answer 24

The blockage of normal transmission of Ach leads to skeletal muscle weakness
Most notable on related attempts at movement
Treatment includes anti-cholinesterase (pyridostigmine) to increase Ach availability at neuromuscular junction.

Question 25

Overstimulation of ACh at neuromuscular junction leads to…

Answer 25

CHOLINERGIC CRISIS (SLUDGE)
- Salivation
- Lacrimation
- Urination
- Defecation
- GI distress
- Emesis

Question 26

Parasympathetic ACh

Answer 26

Rest and digest
Pupils constricts
Decreased HR
BronchoCONSTRICTION
Increased GI motility and secretion
Bladder contraction (detrusor)
Penis Points (erect)

Question 27

Sympathetic NAd

Answer 27

FIGHT OR FLIGHT
Pupils dilate
Increased HR
BronchoDILATION
Decreased GI motility + secretion
Detrusor relaxes
Penis shoots (ejaculation)