Nervous System Question!! Need help quick!!

Question

Myelination speeds up the transmission of information along vertebrate axons. Invertebrates don't have myelination, but if you have ever seen a scorpion stinging its prey, you know that they can move pretty fast... So how do they do it?

a.) What is special about invertebrate nerve fibers that are used for particularly fast transmission of information?

b.) Exactly how does this feature make the transmission faster, i.e. what is the mechanism behind it?

Answer 1

Scorpion muscles are striated (there are roughly 40 muscles in the tail), with individual nerve fibres innervated by several neurons. Multiple muscle fibres can be connected to a single neuron.There is one main nerve cord that runs down the length of the scorpion. Attached to this one cord are several other ganglia, which may also control the scorpion's movement. When a scorpion stings, the muscular contraction required to strike is related to the rate at which the impulse is delivered rather than the number of fibres contracting at a given time as in the case of vertebrates. The neuromuscular system of a scorpion is capable of producing rapid movements as it has fast (phasic) neurons and can further produce sustained contractions since it has slow (tonic) neurons.