Stress response

Stress response

When the sympathetic nervous system is activated, the brain stimulates the adrenal medulla. The cells in the medulla immediately secrete adrenaline (80%) and noradrenaline (20%).


These hormones stimulate adrenergic receptors throughout the whole body. Adrenaline mobilises glucose, fatty acids and energy, and increases heart rate and force of muscle contraction.


I. Acute stress results in higher blood pressure within seconds.

II. Chronic stress is mediated by noradrenaline.