The adrenal glands are pyramid-shaped glands which, despite their small size, are very important for the body's functions.

One adrenal gland sits on top of each kidney. They are, however, not involved in any way in the function of the kidneys.

Each adrenal gland is composed of two distinct parts: the outer part called the adrenal cortex and the inner part adrenal medulla. The hormones they release have quite different functions.

The adrenal medulla produces adrenaline and noradrenaline. These hormones are responsible for all the physiological characteristics of the stress response, also known as the 'fight or flight' response. These hormones increase the heart rate, direct blood into the muscles, improve oxygen intake and raise blood sugar levels. The muscles, the brain and the heart will then function rapidly. If the levels of these hormones are constantly high due to mental strain, the result can be a permanent state of stress, which is harmful to the body.

The adrenal cortex produces a variety of hormones that regulate the correct levels of sugars, salts and calcium in the body.

One such hormone is cortisol, which stimulates glucose production. It is also an important stress hormone, because it regulates the sleep-wake rhythm.

adrenal gland hormones

Endocrine gland	Hormone	Effect
adrenal cortex	mineralocoricoids	Affect the metabolism of minerals. For example, aldosterone increases the function of the cellular sodium pump in the kidney.
adrenal cortex	glucocoricoids	Affect glucose metabolism. For example, cortisol affects hepatic glucose production → blood glucose increase.
adrenal medulla	adrenaline and noradrenaline	Increase physical performance. For example, adrenaline raises blood pressure.