Among the following elements, which one is essential for the transmission of impulses in the nerve fibre?

The transmission of impulses in a nerve fibre, known as an action potential, is primarily driven by the movement of sodium (Na+) and potassium (K+) ions across the neuronal membrane [t4]. When a stimulus reaches the excitation threshold, voltage-gated sodium channels open rapidly, allowing an influx of sodium ions into the cell [t2][t3]. This influx causes depolarization, shifting the membrane potential from negative to positive, which is the fundamental mechanism for generating and propagating the electrical impulse along the axon [t4][t5]. While calcium is essential for triggering neurotransmitter release at the synapse (the gap between neurons), the actual conduction of the impulse within the nerve fibre itself is critically dependent on sodium [t1][t2]. Iron and zinc do not play direct roles in the ionic flux required for action potential propagation [t7].

Sources

1. [1] https://www.sciencedirect.com/topics/neuroscience/neuronal-excitability
2. [2] https://www.ncbi.nlm.nih.gov/books/NBK538143/
3. [3] https://www.science.gov/topicpages/c/calcium+action+potentials
4. [4] https://www.sciencedirect.com/topics/neuroscience/ion-homeostasis