How do kidneys work? Inside each kidney there are more than one
million tiny units called nephrons. Each nephron is made up of a
very small filter called a glomerulus, which is attached to a
tubule. Water and waste products are separated from the blood by
the filters and flow into the tubules. Much of this water is
reabsorbed by the tubules and the wastes are concentrated into
urine. What Kidneys Look Like An enlarged view of a nephron The
urine is collected from the tubules in a funnel-like renal
pelvis and then flows through a tube called the ureter into the
bladder. The bladder stores urine until you urinate. Urine
passes out of the body through a tube called the urethra. The
kidney normally makes one to two litres of urine every day
depending on how much you drink. The normal kidney has the
ability to greatly increase its workload. If one kidney is lost,
the other kidney can enlarge and do the work of two.