Question

1. Running along each side of the back of a squid is a tube-like structure that can be as large as 1.5 mm in diameter in some species. Originally thought to be blood vessels, in the late 1930s the anatomist J.Z. Young discovered that the structures are connected to the nervous system, not to the heart. Although the vast majority of axons in the squid range in diameter from about 10 μm to 50 μm, as squid develop, axons from about 30,000 neurons fuse together to form the giant axons. (a) Compare the longitudinal resistance of a giant axon to that of one of the same length but a more typical diameter. (0.0011) (b) A representative value of the resistivity of a squid axon is 3100 W m. Taking the diameter of a typical axon of one of these cells to be 50 μm and the length to be 10 cm, find the longitudinal resistance of a giant squid axon by considering it as 30,000 separate axons in parallel. (5.3 MW)

Answer 1

Given that

d(giant)=1.5 mm

d(typical)=50 m

resistivity =3100 W m

N=30000

L=0.1 m