Caption

Kidney. Gross specimen of a normal human kidney in section. Blood vessels and the ureter (which carries urine to the bladder) have been removed. The white areas are the renal calices. These collect urine as it leaves the kidneys and enters the urethra. The dark red tissue is the renal cortex. This contains millions of "nephrons", which act as microscopic blood-filtering units. The nephrons remove harmful waste products, toxins and excess water from the bloodstream, all of which then drain to the bladder as urine. There are two kidneys in the human body, both in the lower abdomen. Each is about 10cm long and shaped like a bean.