Credit: NIH.

A nephron is the microscopic unit of the kidney consisting of a glomerulus (a filtering funnel consisting of a cluster of tiny blood capillaries) cupped in a structure called a Bowman's capsule, or renal capsule, with an attached long, narrow tubule. A Bowman's capsule has special epithelial cells (podocytes) that allow fluid filtered from the blood to pass into the nephron.


Blood enters the kidney under pressure, and water and wastes are forced into the tubule by a process known as ultrafiltration. Some water, salts, and other essential molecules are reabsorbed into the bloodstream; the remaining filtrate, urine, is passed to the bladder for excretion from the body.


There are about one million nephrons in each kidney.



Nephritis is Inflammation affecting the kidneys. The term glomerulonephritis covers a variety of diseases, often involved disordered immunity, in which renal glomeruli are damage by immune complex deposition (e.g. Bright's disease; by direct autoimmune attack (Goodpasture's syndrome), or sometimes as a part of systemic disease (e.g. lupus, endocarditis, diabetes, or hypertension. Acute pyelonephritis is bacterial infection of the kidney and renal pelvis, following sepsis or lower urinary tract infection. Typically, this involves fever, loin pain, and painful, frequent urination.