<Tr> <Td> Cockroach (Periplaneta) </Td> <Td> Giant fiber </Td> <Td> − 70 </Td> <Td> 80--104 </Td> <Td> 0.4 </Td> <Td> 10 </Td> </Tr> <Tr> <Td> Frog (Rana) </Td> <Td> Sciatic nerve axon </Td> <Td> − 60 to − 80 </Td> <Td> 110--130 </Td> <Td> 1.0 </Td> <Td> 7--30 </Td> </Tr> <Tr> <Td> Cat (Felis) </Td> <Td> Spinal motor neuron </Td> <Td> − 55 to − 80 </Td> <Td> 80--110 </Td> <Td> 1--1.5 </Td> <Td> 30--120 </Td> </Tr> <P> Given its conservation throughout evolution, the action potential seems to confer evolutionary advantages . One function of action potentials is rapid, long - range signaling within the organism; the conduction velocity can exceed 110 m / s, which is one - third the speed of sound . For comparison, a hormone molecule carried in the bloodstream moves at roughly 8 m / s in large arteries . Part of this function is the tight coordination of mechanical events, such as the contraction of the heart . A second function is the computation associated with its generation . Being an all - or - none signal that does not decay with transmission distance, the action potential has similar advantages to digital electronics . The integration of various dendritic signals at the axon hillock and its thresholding to form a complex train of action potentials is another form of computation, one that has been exploited biologically to form central pattern generators and mimicked in artificial neural networks . </P>

A membrane depolarization that leads to an action potential in a sensory neuron is