Examining artifacts you gathered on a trip, you accidentally stick your finger a

Question

Examining artifacts you gathered on a trip, you accidentally stick your finger and shortly notice that your muscles are not relaxing quickly. You go to the hospital but electrical recordings of the muscles in your arm show mornal frequencies and amplitude of action potentials. Muscles are showing a normal muscle contraction phase but a relaxation phase more like a smooth muscle.

How is the toxin affeting the skeletal muscle contraction?
Explain how this toxin would affect your ability hold a fifteen pound dumbbell out to your side with your arm extended.
What is plausible mechanism to explain your answer in the previous question?

Explanation / Answer

As per the description given, the toxin is possibly tetanus toxin, most likely Tetanospasmin. Tetanus toxin enters into the body during the deep penetrating injuries by pointed objects .This toxin is usually produced bactrrbac infection called Clostridium tetani.

The tetanus toxin will cause a characteric muscle contraction abnormality state called Tetany. Localised injury to a finger causes a type of tetanus called Localised tetanus. The toxin will enter into the axoplasm on the neurons from the injury site by a process called Retrograde transport. This toxin enters into the spinal cord and inhibits the central inhibitory neurons called Interneurons in the spinss cord. These neurons are known to regulate the flow of nerve impulses from brain to peripheral muscles. Such loss of regulation will result in sustained muscle contraction.

Holding a 15 pound dumbbell, is an act of sustained muscle contraction. This can vary from physiological to pathological processes. The pathological state being Tetany. Here the muscle amplitudes and Action potential remains normal, but greater number of motor ( muscle units) are stimulated which causes sustained contraction. Hence holding out a 15 pound dumbbell don't cause much distress or difference from voluntary muscle holding.

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