Muscle relaxants

Question 1

The motor neurone:
>Function?
>Origins
>Speed?

Answer 1

Nerves that control skeletal muscle
Anterior horn of spinal cord
Fast

Question 2

The neuromuscular junction is comprised of:

Answer 2

The motor neurone and motor end plate (divided by the synaptic cleft)

Question 3

Acetylcholine (ach)
>Where is it made?
>Where is it stored?
>When in it released?

Answer 3

Made in the neuromuscular junction
Stored in vesicles
On depolarization - can also be spontaneous

Question 4

Where (other than the NMJ) would you find acetylcholine?

Answer 4

Parasympathetic nervous system

Question 5

Where does Ach work in the heart

Answer 5

Muscarinic receptors to cause vagal stimulation

Question 6

Muscarinic stimulation by Ach leads to

Answer 6

Bradycardia

Pupils constrict

Question 7

Acetylcholine 
T/F
>Is synthesized by alpha-motor neurones
> Contains a tertiary amine group
> Choline is an essential amino acid
> Requires oxidative phosphorylation for its precursor acetyl-coa
> Contains a single ester linkage

Answer 7

> True
False - it contains a quaternary ammonium ion
False - essential nutrient NOT essential amino acid
False - Acetyl-CoA is formed from oxidative decarboxylation of pyruvate
True

Question 8

What is an amine?

Answer 8

A nitrogen bound
to 4 - quaternary - anion
to 3 - tertiary - not an ion - more lipid soluble

Question 9

Why are tertiary amines relevant?

Answer 9

Not ions
More lipid soluble
Cross blood brain barrier

Question 10

Can acetylcholine cross the blood brain barrier ?

Can acetlycholine cross the placenta?

Answer 10

NO
NO
not lipid soluble

Question 11

Draw the cross section of an acetylcholine receptor

Answer 11

5 subunits
From 12oclock clockwise
alpha, beta, alpha, delta, epsilon

Question 12

Where does ach bind on the receptor?

Answer 12

On the alpha sub-unit

Question 13

Atracurium

Description

Elimination

Duration

Usefulness in which comorbidities

Cautions

Side effects

Dose

Answer 13

Benzylisoquinolinium
Non-depolarising muscle relaxant

Temperature and PH dependent Hofmann elimination + non specific enzymatic water hydrolysis

20-30mins

Severe renal or hepatic disease

Neuromuscular blockade potentiated by

Induction- 0.3-0.5mg/kg
Maintenance- 0.1-0.2mg/kg

Question 14

How do you present drugs

Answer 14

C class
A action 
M mechanism of action 

K pharmacokinetics (absorption/ distribution/ elimination)
A adverse effects
T toxicity
E elimination

Question 15

What’s the difference between pharmacokinetics and pharmacodynamics

Answer 15

Dynamics - how the drug acts on the body

Kinetics - how the body acts on the drug