Structure of Kidney:

The kidneys are bean-shaped organs located in the abdominal cavity, one on each side of the spine.

They are about the size of a fist and are essential for maintaining proper fluid and electrolyte balance in the body.

Each kidney has an outer cortex and an inner medulla.

The renal hilum is a concave area on the medial side of the kidney where blood vessels, nerves, and the ureter connect.

The renal pelvis is a funnel-shaped structure that collects urine from the nephrons and funnels it into the ureter.

The renal artery brings oxygenated blood to the kidney, and the renal vein carries filtered, deoxygenated blood away from the kidney.

Structure of Nephron:

Nephrons are the functional units of the kidney responsible for filtering blood and producing urine.

Each kidney contains about 1 million nephrons.

Each nephron consists of a renal corpuscle (glomerulus and Bowman’s capsule) and a renal tubule.

The glomerulus is a network of tiny blood vessels where blood filtration occurs.

Bowman’s capsule surrounds the glomerulus and collects the filtered fluid (filtrate).

The renal tubule consists of the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and the collecting duct.

Structure of Glomerulus:

The glomerulus is a knot of capillaries located within the Bowman’s capsule of the nephron.

It is highly specialized for filtration and is involved in the initial step of urine formation.

The glomerular capillaries have a high pressure that forces small molecules and water out of the bloodstream into Bowman’s capsule.

The fenestrated (porous) capillary walls and the presence of podocytes (cells in Bowman’s capsule) with foot-like extensions contribute to the filtration process.

Function of Adrenal Gland in Excretion:

The adrenal glands are situated on top of each kidney and consist of two parts: the adrenal cortex and the adrenal medulla.

The adrenal cortex produces hormones called corticosteroids, including aldosterone.

Aldosterone plays a crucial role in the regulation of electrolytes, particularly sodium and potassium, which are essential for maintaining proper fluid balance in the body.

Aldosterone acts on the distal convoluted tubules and collecting ducts of the nephrons in the kidney.

It increases the reabsorption of sodium ions and the excretion of potassium ions, helping to regulate blood pressure, blood volume, and electrolyte levels.

By influencing the reabsorption of sodium, aldosterone indirectly affects water reabsorption, further contributing to fluid balance.