How the bladder works
Each time you eat and drink, your body absorbs liquids. The kidneys filter out waste and extra water to make urine, which is stored in your bladder. Nerves tell the brain when the bladder is full. That's when you get the feeling that you need to go to the bathroom.
A normal bladder muscle sends a strong signal when it's full
It expands like a balloon to hold a cup or two of urine. As it fills, it sends stronger and stronger signals that it's time to go. When you feel ready, you go to the bathroom.
An overactive bladder muscle sends "false alarms" before it's full
It doesn't wait until it's full to send an urgent signal. These "false alarms" can cause strong sudden urges to urinate. And may even lead to an accident. A strong sudden urge to urinate is also known as "urgency."
