Definition of Adrenal Gland

The adrenal glands, located above each kidney, are endocrine glands. These two small but important glands release hormones that control components of metabolism, water and salt balance, sexual maturation, pregnancy and the body's response to stress. The adrenal glands, along with other glands of the endocrine system, regulate body processes by using hormones to send long-distance chemical messages to cells throughout the body.

Features

Each adrenal gland is composed of two main functional areas--the outer adrenal cortex and the inner adrenal medulla. The adrenal cortex and the adrenal medulla secrete entirely different types of hormones that differ in their action. Because the cortex and medulla are so distinct functionally, the adrenal glands are sometimes considered to be two endocrine glands with one gland surrounding the other. The adrenal glands produce several types of hormones including catecholamine hormones, mineralocorticoids, corticosteroids and androgens.

Cortex Function

The hormones secreted by the adrenal glands have distinct tasks that regulate functions of the body. The corticosteroid hydrocortisone secreted by the adrenal cortex regulates how the body uses fat, carbohydrates and protein and works with cortisone to control inflammatory reactions in the body. Aldosterone, also secreted by the cortex, manages salt excretion, blood pressure and volume. Hormones called androgens, which assist in the development of sex characteristics are also secreted by the cortex of the adrenal glands.

Medulla Function

The hormonal functions of the adrenal medulla are not as critical as the functions of the adrenal cortex hormones. The primary role of the medulla is to secrete hormones that assist the body in responding to stress. These hormones, mainly epinephrine (adrenaline) and norepinephrine (noradrenaline), are part of the "fight or flight" response that occurs in the body when you encounter stressful, dangerous or frightening situations. When released, these hormones prepare the body for action (fight) or escape (flight).

Disorders

Health disorders arise when the adrenal glands do not function properly, making either too little or too much of a particular hormone. Addison's disease occurs as a result of low adrenal gland function and Cushing's syndrome occurs when the adrenals overproduce corticosteroids. Disorders of the adrenal glands can arise from the dysfunction of the gland itself, as is the case with adrenal tumors, or from issues with a gland that helps to regulate the adrenal glands, which happens with some pituitary tumors.

Prevention/Solution

The specific treatment of any adrenal gland disorder depends on the underlying cause of the disease. In the case of Addison's disease, synthetic corticosteroids are given to compensate for a reduction in the level of adrenal hormones. Cushing's syndrome might be treated with surgery or radiation if a tumor is involved or might be managed with medications. The cause of many adrenal gland disorders is unknown and therefore these disorders are typically not preventable.

Resources

• More Information on the Adrenal Glands