Bladder

The aging bladder is characterized by a decrease in capacity and urinary flow, and an increase in urgency and amount of residual urine. The changes contribute to a increase in nocturia (frequent urination at night) as well as a higher rate of urinary tract infections among the elderly.

This figure shows the difference in glomerular filtration rate (GFR) for a young and an old kidney. The process is based on two stages. First, the oxygenated blood flows in the kidney (the kidney is more RED). Secondly, as the larger particles are being taken out of the blood (the cup is filling up) and the de-oxygenated blood (the kidney is more BLUE) is flowing out of the kidney. The older kidney has a lower concentration of the urine (lighter yellow with fewer particles in it).