Final answer:
The adrenal medulla secretes catecholamines, specifically epinephrine and norepinephrine, which are crucial for the body's immediate stress response, leading to increased heart rate, blood glucose levels, and metabolic changes to support the fight-or-flight response.
Step-by-step explanation:
The adrenal medulla secretes two main types of hormones: catecholamines, which include epinephrine and norepinephrine. These hormones are responsible for the body's quick response to stress, often referred to as the fight-or-flight response. Epinephrine, which accounts for 75 to 80 percent of the secretions from the adrenal medulla, alongside norepinephrine, increases heart rate, breathing rate, cardiac muscle contractions, blood pressure, and blood glucose levels.
They also play a role in breaking down glucose in skeletal muscles and stored fats in adipose tissue. The adrenal medulla's function contrasts with that of the adrenal cortex, which produces corticosteroids such as glucocorticoids and mineralocorticoids, and is more involved in long-term stress response.