What is one of the key functions of the substance produced by the zona glomerulosa?

The substance produced by the zona glomerulosa is primarily aldosterone, which plays a crucial role in electrolyte and fluid homeostasis. Aldosterone is a mineralocorticoid hormone that promotes the reabsorption of sodium and the excretion of potassium in the kidneys. This action helps to regulate blood pressure and maintain the balance of fluids and electrolytes in the body. By influencing the amount of sodium reabsorbed into the bloodstream, aldosterone promotes water retention, thus ensuring that the body maintains an appropriate blood volume and pressure.

While the other functions mentioned, such as managing stress responses and regulating cholesterol levels, are important physiological processes, they are not directly linked to the specific function of the zona glomerulosa. Insulin production is related to the pancreas and not the adrenal glands, making it irrelevant in this context. Therefore, the key function of the zona glomerulosa's secretion is indeed primarily focused on electrolyte and fluid balance, highlighting the importance of aldosterone in maintaining homeostasis within the body.