Adrenal Gland | Anatomy and Physiology

The adrenal glands are two small glands located on top of each kidney. They produce hormones that help the body respond to stress, including adrenaline and cortisol. The outer layer of the gland, called the adrenal cortex, produces hormones that are important for regulating metabolism, electrolyte balance, and blood pressure. The inner layer of the gland, called the adrenal medulla, produces hormones that help the body respond to stress, such as adrenaline. Dysfunction of the adrenal glands can lead to a variety of health problems, including Addison's disease and Cushing's syndrome.
The adrenal glands are located on both sides of the body in the retroperitoneum, above and slightly medial to the kidneys. In humans, the right adrenal gland is pyramidal in shape, whereas the left is semilunar or crescent shaped and somewhat larger.[8] The adrenal glands measure approximately 5 cm in length, 3 cm in width, and up to 1 cm in thickness.Their combined weight in an adult human ranges from 7 to 10 grams.
The adrenal cortex is the outer region and also the largest part of an adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones. The adrenal cortex is the outermost layer of the adrenal gland. Within the cortex are three layers, called "zones". When viewed under a microscope each layer has a distinct appearance, and each has a different function. The adrenal cortex is devoted to production of hormones, namely aldosterone, cortisol, and androgens.
The adrenal glands are composed of two heterogenous types of tissue. In the center is the adrenal medulla, which produces adrenaline and noradrenaline and releases them into the bloodstream, as part of the sympathetic nervous system. Surrounding the medulla is the cortex, which produces a variety of steroid hormones. These tissues come from different embryological precursors and have distinct prenatal development paths.