What component constitutes the majority of the adrenal gland?

The adrenal gland is comprised of two main regions: the adrenal cortex and the adrenal medulla. The adrenal cortex is the outer layer of the gland and constitutes the majority of its mass. It is responsible for producing a variety of hormones, including cortisol, aldosterone, and androgens, which are critical for metabolic processes, stress response, and maintaining electrolyte balance.

In contrast, the adrenal medulla, which is located in the center of the adrenal gland, primarily produces catecholamines such as adrenaline and noradrenaline, and it is significantly smaller in size compared to the cortex. The renal cortex is part of the kidney, and the outer capsule is the connective tissue layer that encases the adrenal gland but does not contribute to its functional mass. Therefore, recognizing the adrenal cortex's predominant role in both structure and function explains why it constitutes the majority of the adrenal gland.