How The Bladder Works

To understand how therapy will help you control your symptoms, it is important to first understand how the bladder works.

Bladder

Your bladder is the hollow muscular organ that stores your urine. It's a bit like a floppy balloon - as your bladder fills, it expands to store the urine. On average, your bladder can hold 400-600ml of urine for up to about five hours.

The muscle in your bladder wall is called the detrusor muscle. The detrusor muscle relaxes to allow your bladder to fill. When you go to the toilet, it contracts to squeeze out urine.

Urethra

At the bottom of your bladder is the urethra.The urethra is the canal that carries urine from the bladder out of the body. This is a tube about 4cm long that runs from the neck of your bladder to the outside of your body, just in front of your vagina or through the length of your penis. The urethra has two outlet valves called sphincters.

Sphincters

There are two sphincter mechanisms. The internal sphincter is a ring of muscle that holds the neck of the bladder in place. Your body opens and shuts it automatically without you thinking about it.

The external sphincter acts like a tap and keeps urine in the bladder. It is controlled by the pudendal nerve, which is controlled by the voluntary nervous system. This means it's under your control - you decide when to let it open. The external sphincter is also called the distal sphincter.

Your Pelvic Floor

The bladder is a part of the “pelvic floor.” The pelvic floor is the group of muscles located between your hips and below your belly button.

The pelvic floor also keeps your urethra closed until you're ready to pass water.squeezes when you cough or sneeze, to help stop urine leaking.controls the expulsion of wind.increases your sexual awareness during intercourse.

Just like other muscles, the pelvic floor can become weak or damaged.

How do you know when to empty your bladder?

The micturition reflex tells you when you need to empty your bladder. This happens on average four to eight times a day. The reflex is controlled by your central nervous system.

When your bladder is about half full, the stretch receptors in the walls of your bladder become active and send signals along your pelvic nerves to your spinal cord.

A reflex signal is sent back to your bladder, which makes the detrusor muscle in the bladder wall contract. The contraction increases the pressure in your bladder, and this is what makes you want to pass urine.

Because the external sphincter is under voluntary control, you don't urinate until you decide to relax this muscle.

What happens when you urinate

Signals from the brain tell muscles around the opening of the bladder when to relax and the bladder itself when to contract in order to let urine flow out of the body.

• to your detrusor muscle in the bladder wall, telling it to contract and squeeze the urine out into the urethra
• to your sphincter, telling it to relax and open
• to your pelvic floor, telling it to relax and allow the sphincter to open.

When your bladder is empty, your sphincter closes, your pelvic floor tightens and your detrusor muscles relax, allowing your bladder to fill and expand again.

If any of these muscles or systems become damaged or weak, a bladder control problem can occur.