What hormone do adrenal glands primarily secrete when the body is under stress?

The primary hormone secreted by the adrenal glands in response to stress is cortisol. When the body perceives a threat or stressor, the adrenal glands produce cortisol as part of the body's "fight or flight" response, which helps to manage stress by increasing blood sugar levels, enhancing memory formation, and suppressing the immune system to prioritize energy use.

While adrenaline, also known as epinephrine, is indeed released during stressful situations and prepares the body for immediate action, cortisol plays a more significant role in the sustained response to chronic stress. It helps regulate metabolism and maintain homeostasis during prolonged disruptions. The production of insulin is not directly related to stress response but rather regulates blood sugar levels, and serotonin is a neurotransmitter important for mood regulation, not linked to the stress response from the adrenal glands. Therefore, cortisol is the most accurate answer when considering adrenal gland activity during stress.