The adrenal gland, as we can presume based on the name, is a glandular tissue located above the kidneys. Morphologically, the adrenal glands resemble shells in the sea, lying on the upper edge of the kidneys on each side. Don’t look at the small size of the adrenal gland, it plays a very big role in the body. It can be said that the human body can hardly survive without it. The adrenal glands are composed of two parts: the inner and outer parts. 1. The outside is the cortical part, which secretes aldosterone, cortisol and a small amount of estrogen. Aldosterone promotes the excretion of urinary potassium and the reabsorption of urinary sodium in the urine. Aldosterone, in normal quantities, is important for maintaining normal blood pressure in the body. However, if it is secreted in excess, it can lead to hypertension and hypokalemia. Cortisol is one of the essential hormones in the body. When the body is in a state of stress, such as a cold, a fever, or an unexpected event, the adrenal cortex secretes large amounts of cortisol, which mobilizes the body’s stored energy and provides adequate material preparation to respond to important internal or external events. When cortisol is deficient, the body often lacks the ability to cope adequately with major events and is easily overwhelmed by viruses or external stresses. The androgens produced by the adrenal glands are not essential for men, but for women, they are an important source of androgens. 2. Inside the adrenal glands is the medullary part, which secretes adrenaline and noradrenaline. These hormones are released more during stress and can help raise blood pressure, speed up heart rate, raise blood sugar and mobilize the body’s reserves to prepare the body to fight against the external environment. Thus, the adrenal gland is an important gland in the body. All its activities are finely regulated by both the pituitary gland and the nerve center. For example, the secretion of aldosterone is regulated by renin in the kidneys, and the secretion of cortisol and androgens is regulated by ACTH in the pituitary gland. Adrenaline and noradrenaline are regulated by the sympathetic nervous system.