Which two ions are primarily responsible for the active secretion of aqueous?

The active secretion of aqueous humor in the eye primarily involves the transport of sodium ions (Na+) and bicarbonate ions (HCO3-). This process occurs in the ciliary body, specifically within the non-pigmented epithelial cells that line the posterior chamber of the eye.

Sodium ions play a crucial role by being actively transported across the cell membrane into the aqueous humor. The active transport of Na+ creates an osmotic gradient that facilitates the movement of water into the aqueous humor, contributing to the volume of aqueous produced. Additionally, bicarbonate is involved in regulating the pH of the aqueous humor and, together with sodium, helps maintain the necessary ionic environment for proper eye function. The cooperative transport of these ions effectively drives the secretion process, leading to the formation of aqueous humor, which is vital for maintaining intraocular pressure and providing nutrients to avascular structures within the eye.

While other ions may participate in various roles in ocular physiology, it is the combination of sodium and bicarbonate that is specifically recognized as the primary driving force behind the active secretion of aqueous humor.