Final answer:
The adrenal gland is covered by a fibrous capsule, under which lies the adrenal cortex with its three layers: the zona glomerulosa, zona fasciculata, and zona reticularis. The adrenal medulla sits below the zona reticularis.
Step-by-step explanation:
The adrenal gland is a complex endocrine organ consisting of both an outer cortex and an inner medulla. Starting from the top exterior, the gland is covered by a fibrous capsule, and under it lies the adrenal cortex, which can be subdivided into three distinct layers:
- Zona glomerulosa: the outermost layer that produces mineralocorticoids, primarily aldosterone.
- Zona fasciculata, the middle and largest layer of the adrenal cortex, is responsible for producing glucocorticoids, like cortisol.
- Zona reticularis: the innermost layer before you reach the adrenal medulla, which produces androgens.
Below the zona reticularis is the adrenal medulla, which is the innermost part of the gland, producing catecholamines such as epinephrine and norepinephrine.