Final answer:
The cochlea's endolymph is high in potassium ions, which contrasts with the sodium and chloride ions prevalent in extracellular fluids. The sodium-potassium pumps help maintain this ion balance, which is vital for the function of the ear in hearing.
Step-by-step explanation:
The endolymph in the cochlea, when uncoiled, is high in potassium ions (K+). This is in contrast with most extracellular fluids (ECF) in the body, where sodium (Na+) and chloride (Cl-) ions are more concentrated. Within the cells, a higher concentration of potassium ions is maintained by the sodium-potassium pumps. These pumps actively transport potassium ions into the cell while pumping sodium ions out, using ATP as an energy source.
In the inner ear, specifically in the cochlea, the movement of the endolymph and perilymph stimulates the hair cells in the organ of Corti. The bending of cilia on the hair cells generates nerve impulses that are sent to the brain, allowing us to process sound. The balance of ions across cell membranes is crucial for maintaining the electric potential necessary for this signal transduction in auditory processing.