Question

Which movement of ions produces EPSPs in cochlea hair cells?

A) Efflux of Ca++
B) Influx of Na+
C) Efflux of K+
D) Influx of K+ and Ca++

Answer 1

EPSPs in cochlea hair cells are produced by the influx of K+ and Ca++ ions, which leads to membrane depolarization and subsequent neurotransmitter release.

Step-by-step explanation:

The movement of ions that produces excitatory postsynaptic potentials (EPSPs) in the cochlea hair cells is specifically the influx of K+ and Ca++. When neurotransmitters bind to the receptors on hair cells, it leads to the opening of ion channels that allow these ions to enter the cell. This influx of K+ and Ca++ ions results in the depolarization of the membrane, contributing to the generation of an EPSP. The entry of Ca++ ions further plays a role in the release of neurotransmitters from the hair cells, propagating the signal.

The process is initiated by a nerve impulse opening the Na+ channel, leading to an inrush of Na+ ions, which depolarizes the membrane. This depolarization is mirrored in the cochlea hair cells with the influx of K+ and Ca++. Following depolarization, the closing of Na+ channels and the opening of K+ channels allow K+ to leave the cell, helping to repolarize the membrane and thus return to its resting potential. In auditory transduction, similar principles apply but the primary event for EPSP generation is the opening of channels allowing K+ and Ca++ to flow into the hair cells.