What is muscle tetany?

[sameeralord]

Hello guys,

Muscle Tetany- is a case of involuntary muscle convulsion. It is a muscular physical state at which action potentials from nerves arrive to the skeletal muscle motor end plate rapidly enough in succession to cause a steady contraction. If the frequency of charge is once per second, the hand muscles (which the ulnar nerve supplies) will flex once per second. If the frequency is increased, the muscle contractions will sum and appear as one smooth contraction. The hand will smoothly close.

So is tetany repeated involuntary contractions or just one smooth contraction? If the rate of action potential is rapid wouldn't that give repeated contractions? Also cardiac muscle doesn't have tetany for some reason? Thanks for anyone who can improve my understanding of tetany. Thanks!

 

[Moonbear]

Yes. You've pretty much restated the definition. You get a lot of really rapid action potentials that don't give enough time in between them for the muscle to relax. The means the muscle is in a continuous state of contraction during the period of tetany, but due to many action potentials that keep sending signals to keep contracting.