Question

Which among the following is chiefly responsible for maintaining electrochemical ionic gradient i.e. resting potential across axolemma?
O Na*/K ATPase
O Voltage gated Na* channels
O Voltage gated K channels
O Leaky channels for K​

Answer 1

Answer:

Of these various transporters, the best understood is the Na+/K+ pump. The activity of this pump is estimated to account for 20–40% of the brain's energy consumption, indicating its importance for brain function. The Na+ pump was first discovered in neurons in the 1950s, when Richard Keynes at Cambridge University used radioactive Na+ to demonstrate the energy-dependent efflux of Na+ from squid giant axons. Keynes and his collaborators found that this efflux ceased when the supply of ATP in the axon was interrupted by treatment with metabolic poisons (Figure 4.10A, point 4). Other conditions that lower intracellular ATP also prevent Na+ efflux. These experiments showed that removing intracellular Na+ requires cellular metabolism. Further studies with radioactive K+ demonstrated that Na+ efflux is associated with simultaneous, ATP-dependent influx of K+. These opposing fluxes of Na+ and K+ are operationally inseparable: Removal of external K+ greatly reduces Na+ efflux (Figure 4.10, point 2) and vice versa. These energy-dependent movements of Na+ and K+ implicated an ATP-hydrolyzing Na+/K+ pump in the generation of the transmembrane gradients of both Na+ and K+. The exact mechanism responsible for these fluxes of Na+ and K+ is still not entirely clear, but the pump is thought to alternately shuttle these ions across the membranes in a cycle fueled by the transfer of a phosphate group from ATP to the pump protein

Explanation: