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Overactive Bladder, What Is It?

Overactive bladder, irritable bladder, detrusor over-activity what do these terms really mean to you.

What is an overactive bladder?

First let's start with a review of the bladder. The bladder is a hollow organ with strong smooth muscle walls that acts as a receptacle for the storage of urine.

Yes, there is a muscle that forms the walls of the bladder. This muscle is called the detrusor muscle. This muscle remains in a relaxed stated when the bladder is filling with urine. When the bladder fills with approximately 150-200 mL of urine you will feel the first urge to urinate. The urge is caused by a stretch to the walls of the bladder.

This stretch stimulates receptors in the wall of the bladder. A message is sent to the spinal cord which in turn sends a message to the detrusor muscle to contract. If the bladder is not full and we resist the urge to urinate our urethral sphincters and our pelvic floor contract. These contractions send a signal to the spinal cord which in turns sends a message to the detrusor to stop contracting. At this point the urge to urinate passes and we go about our daily tasks.

The bladder is capable of holding approximately 600mL of urine. When the bladder has met capacity and we are ready to urinate. The detrusor contracts while the urethral sphincters and pelvic floor relax thus allowing the urine to pass freely through the urethra.

Woah...pretty complicated.

Below is a video to help explain/demonstrate the process.