Adrenaline is secreted by the adrenal medulla. There is a cap-like structure above the human kidney, medically known as the adrenal gland. The adrenal gland is a gland with endocrine function and its anatomy can be divided into cortex and medulla, i.e. the outermost layer of the adrenal gland is the cortex and the innermost layer is the medulla. The cortex mainly secretes glucocorticoids and salt corticoids, and also secretes androgens, which are mainly derived from the adrenal cortex in women. The inner medulla mainly secretes catecholamines, which include adrenaline, norepinephrine and dopamine. Therefore, adrenaline is a hormone secreted by the adrenal medulla.