In the Netherlands a young man named Jan was admitted to the emergency room. He and his friends had been to a rave. His friends say he started twitching and having muscle spasms which progressed until he was 'stiff as a board.' On examination, staff found a marked increase in muscle tone and hyperreflexia involving facial and limb muscles. In his pocket, he had unmarked dark yellow tablets with dark flecks. Analysis of the tablets showed them to contain a mixture of ecstasy and strychnine. Ecstasy would not cause this clinical picture, but strychnine, which blocks glycine receptors, could. Explain how.

Video transcript

Welcome back, everyone. Here's our next question. Suppose. A pill contains a combination of a stimulant and a compound that blocks glycine receptors based on its given action mechanism. Which of the following will be experienced by the patient. If the pill is taken at an excessive dosage, a muscle spasm B, headache, C, hyper acidity or D bone suppleness. Well, we're talking about a medication that would block glycine receptors and glycine is an inhibitory neurotransmitter and it binds to receptors on motor neurons. And since it's inhibitory when it is bound to those receptors, it turns down the activity of the motor neurons which reduces their activity and prevents excessive muscle contractions. So, if our medication blocks the glycine receptors that prevents that inhibition from taking place. Well, if the inhibitory effect of glycine is to prevent excessive muscle contractions, then an expected side effect. If you took an excessive amount of this medication would be choice a muscle spasm which would be essentially a excessive muscle contraction. Now, when we look at our other uh effects that you might see headache, hyper acidity, bone suppleness, we can say that those would not be expected to be effects So we'll cross them out because glycine only acts on motor neurons that control either directly or indirectly muscles and glands. So you wouldn't expect to see these effects um from something that interacts with just motor neurons. But muscle spasm would definitely be an expected um experience if there's too much of this medication taken doing due to the fact that it interferes with the inhibition of glycine. So choice a muscle spasm would be our answer here. See you in the next video.