Suprarenal Gland-

The suprarenal Gland are endorine glands which help to maintain water and electrolyte balance. These also prepare the body for any emergency. These are subjected to hyper or hypofunctioning.

Lack of secretion of the cortical part leads to Addison’s disease. Excessive secretion causes retention of salts and fluids.

Subdivisions-

The suprarenal Gland are a pair of important endocrine glands situated on the posterior abdominal wall over the upper pole of the kidney behind the peritoneum.

They are made up of two parts.

1. An outer Cortex of mesodermal origin, which secretes a number of steroid hormones.
2. An inner medulla of neural crest origin, which is made up of chormaffin cells and secretes adrenaline and nonadrenaline or catecholamines.

Location-

Each gland lies in the epigastrium, at the upper pole of the kidney, in front of the crus of the diaphragm, opposite the vertebral end of the 11th intercostal space and the 12th rib.

Size , shape and weight-

Each gland measures 50 mm in height, 30mm in breadth and 10mm in thickness. It weighs about 5g, the medulla forming one tenth of the gland. Right suprarenal is triangular or pyramidal in shape and the left is semilunar in shape.

Sheaths-

The suprarenal Glands are immediately surrounded by areolar containing considerable amount of fat.

Outside the fatty sheath, there is the perirenal fascia. Between the layers of fascia lies the suprarenal Gland. The gland is separated from the kidney by a septum.

Right suprarenal Gland-

The right suprarenal Gland is triangular to pyramidal in shape. It has:

1. An apex.
2. A base.
3. Two surfaces- anterior and posterior.
4. Three borders- anterior, medial and lateral.

Left suprarenal Gland-

The left gland is semilunar. It has:

1. Two ends- upper(narrow end) and lower (rounded end).
2. Two borders- medial convex and lateral concave.
3. Two surfaces- anterior and posterior.

Structure and function-

Naked eye examination of a cross section of the Suprarenal Gland shows an outer part, called the Cortex, which forms the main mass of the gland, and a thin inner part, called the medulla, which forms only about one tenth of the gland.

The two parts are absolutely distinct from each other structurally, functionally and developmentally.

Functions-

Cortex-

The Cortex is composed of three zones

• The outer, zona glomerulosa which produces mineralocorticoids that affect electrolyte and water balance of the body.
• The middle, zona fasciculata which produces glucocorticoids.
• The inner, zona reticularis which produces sex hormones.

Medulla-

The medulla is composed of chormaffin cells that secrete adrenaline and noradrenaline.

Arterial supply-

1. The suprarenal artery, a branch of the inferior phrenic artery.
2. The middle suprarenal artery, a branch of the abdominal aorta.
3. The inferior suprarenal artery, a branch of the renal artery.

Venous drainage-

The suprarenal vein drains into the inferior vena cava, and the left suprarenal vein into the left renal vein.

Lymphatic drainage-

Lymphatic from the suprarenal glands drain into the lateral aortic nodes.

Nerve supply-

The suprarenal medulla has a rich nerve supply through myelinated preganglionic sympathetic fibres.

The chormaffin cells in it, are considered homologous with postganglionic sympathetic neurons.