The kidneys filter the blood and help remove waste and extra
fluid from the body. The kidneys also help control the body's
chemical balance. The kidneys are part of the urinary system,
which also includes the ureters, bladder, and urethra. Bladder
control can be affected by muscle changes and changes in the
reproductive system. Aging Changes and Their Effects on the
Kidneys and Bladder As you age, your kidneys and bladder change.
This can affect their functions. Changes in the kidneys: As the
kidneys age, these events occur: - Overall amount of kidney
tissue decreases. - Number of filtering units (nephrons)
decreases. Nephrons filter waste material from the blood. -
Blood vessels supplying the kidneys can become hardened. This
causes the kidneys to filter blood more slowly. Changes in the
bladder: - The bladder wall changes. The elastic tissue becomes
tough and the bladder becomes less stretchy. The bladder cannot
hold as much urine as before. - The bladder muscles weaken. -
Blockage of the urethra: In women