Why were squid giant axons important to studies of nerve impulses?

Squid giant axons were instrumental to the study of nerve impulses primarily due to their exceptionally large diameter, which is many times greater than that of most other nerve fibres. This physical characteristic allowed researchers to insert microelectrodes directly into the fibres to measure their electrical and chemical behaviour.12

By utilizing these giant axons, physiologists Alan Hodgkin and Andrew Huxley were able to demonstrate how the flow of sodium and potassium ions across nerve membranes produces an action potential. Their experiments revealed that, contrary to previous theories suggesting a membrane breakdown, the nerve membrane selectively allows sodium to penetrate the fibre only when it is excited. This foundational work provided the basis for our modern understanding of how nervous signals are propagated.324