What is the bladder ?

How does the bladder work ?

Bladder problems

What is the bladder ?

The bladder is the organ in the body that stores urine. It is like a balloon and changes shape according to how full it is.

When you eat or drink, liquids are absorbed by the body. The role of the kidneys is to filter out waste products, creating urine. Urine drains from the kidneys moving down to the bladder through the ureters.

Urine is made up of three parts; urea, the by-product of the break down of protein, water, and other waste products from the body.

Extending from the bladder is the urethra, which is the outlet for urine. This has two valves; the internal sphincter, which automatically holds the neck of the bladder in place and the external sphincter, which is like a tap. This tap is controlled by the voluntary nervous system.

So the internal sphincter opens and shuts without you having to think about it while you decide when to open and shut the external sphincter.

The female urethra is shorter than the male urethra because of the difference in design of the urinary system between males and females. This means that women tend to get urinary infections more often than men.

How does the bladder work?

The bladder can hold upwards of 400 mls of urine. When it is half full, signals are sent via the pelvic nerves and spinal cord to tell your body that it is time to urinate. A reflex signal is fed back to your bladder and this causes the detrusor muscle in the bladder wall to contract. This steps up the pressure in your bladder producing the urge to urinate.

The detrusor muscle performs a very important function, relaxing to allow your bladder to fill. Then it contracts to squeeze out urine from the bladder.

Before you urinate, your brain makes contact with the detrusor muscle. Three things happen:

• The bladder contracts and squeezes the urine out
• The sphincter relaxes and opens
• The pelvic floor relaxes

Bladder problems

When a problem occurs with any of these mechanisms, this may result in varying degrees of urinary incontinence.

A problem with the reflex signals to the detrusor muscle may leads to overactive bladder or urge incontinence. This is where you lose some control over urinary function.

A weak pelvic floor may lead to stress incontinence or leaking.

Where there is a problem with the signals between the brain and the spinal cord, there may be a mix of overactive bladder and stress incontinence.

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