What gland controls metabolic processes and secretes steroid hormones related to the fight or flight response?

The adrenal gland is responsible for controlling metabolic processes and secreting steroid hormones, particularly during the body's fight or flight response. It is located on top of each kidney and consists of two parts: the adrenal cortex and the adrenal medulla.

The adrenal cortex produces hormones such as cortisol, which helps regulate metabolism and the body's response to stress, and aldosterone, which plays a key role in sodium and water balance. The adrenal medulla, on the other hand, releases adrenaline (epinephrine) and noradrenaline (norepinephrine), which are critical for the fight or flight response, increasing heart rate, blood flow, and energy availability.

In contrast, the thyroid gland primarily regulates metabolism through the production of thyroid hormones but does not largely impact the fight or flight response. The hypothalamus and pituitary gland are also important in hormonal control; the hypothalamus acts as a regulatory center for many hormones and the pituitary gland is often referred to as the "master gland," controlling other glands, but neither directly secretes steroid hormones related to stress responses like the adrenal gland does. Thus, the adrenal gland’s unique function in metabolism and stress response is why it is the correct answer.