21. The Neuromuscular Junction II

Question 1

Describe the two types of NMJ blocking agents and there effects

Answer 1

-Cause paralysis, first with small moving muscles like eyes and fingers then limbs and last respiratory muscles

-Competitive agents like Tubocurarine, compete with ACh for binding to receptor, cause flaccid relaxed paralysis, can be reversed by AChE inhibitors

-Non-Competitive agents like Pancuronium are not reversible.

Question 2

Describe Acetylcholinesterase inhibitors

Answer 2

-Stop enzyme used in the breakdown of acetylcholine eventually leading to paralysis as the muscle becomes desensitised

-Found naturally in venoms and poisons or from weapons like nerve agents and insecticides.

-Can be used medically to treat NMJ disorders

Question 3

Describe Cholinesterase inhibitors

Answer 3

-Increase the availability of ACh partially overcome the decreased receptor availability, but in the later stages of NMJ to many receptors get degraded and can’t be overcome.

-drug example is neostigmine.

Question 4

Describe over-stimulation of the NMJ

Answer 4

-also known as Cholinergic crisis.

-Muscles stop responding to ACh

-Atropine is an antidote.