What Is The Bladder? | Understanding How It Works | TENA

We use our bladders every single day, but most people understand very little about how the bladder functions. For example, they’re pretty tough - which is probably why the first footballs were made from the bladders of pigs or sheep! Also, did you know that people make better liars when their bladders are full? New Scientist found that the control needed to maintain a full bladder helps the individual lie more convincingly1.

Wanting to learn more about this fascinating organ, we spoke to Dr John S. Young, Associate Professor in Urology, to find out about the function of the bladder and what to do if you encounter any problems.

What side is your bladder on?

Your bladder sits in the centre of the pelvis, above and behind the pubic bone. If you feel any pain in your lower left or right abdomen, it’s less likely to be a bladder problem and more to do with your kidneys instead. The bladder is about the shape and size of a pear when empty.

What does the bladder do?

Put simply - the bladder stores urine. Urine is produced by the kidneys and trickles down to the bladder via two tubes (one from each kidney) called the ureters. Dr John describes what happens next:

“As the bladder begins to fill, sensory nerves in its lining begin to tell us that it’s approaching capacity, and we feel an urge to urinate. That urge becomes stronger and more frequent with increasing volume. When it’s an appropriate time and place (i.e. we’ve stopped what we were doing and go to the bathroom), the bladder muscle will contract, squeezing the urine out through the urethra.”

How much urine can the bladder hold?

The bladder acts like a storage tank. As the bladder fills with urine, it expands to accommodate it just like a balloon. In a healthy adult, a normal bladder can comfortably hold between 400ml and 450ml of urine, which is less than a pint of liquid, although patients with obstructions (such as an enlarged prostate) have been known to hold up to 2 litres of the stuff. If you find that your bladder feels overwhelmingly full but you can't release, you may have shy bladder syndrome. Speak to your GP if you struggle to urinate regularly.

How does the bladder work?

Storing and voiding urine as well as  the transition between these states requires the coordination of several organs, including the bladder. As Dr John explains:

“When we’re storing urine, the bladder muscle is relaxed to allow the bladder to fill; while the organs responsible for maintaining continence (the neck of the bladder; the urethra; the pelvic floor muscles) must all be contracted. When we void, it’s the opposite: the bladder muscle contracts, while the neck of the bladder, the urethra and the all relax. This interplay between different organs is complex and requires considerable coordination. As well as nerves that sense pressure (associated with the filling bladder), there are nerves that stimulate or inhibit the muscles of each of the organs.”

“We also know how complicated the bladder is because of the difficulty in getting it to function properly again once a patient experiences urinary symptoms. We still have so much to learn about how the bladder works!”

For advice on increasing control over your bladder, take a look at our guide to bladder training and pelvic floor exercises.

How does bladder health change?

As you get older, your bladder health also changes. Dr John tells us: “we know that the bladder muscle can change in its flexibility and the way it generates contractions. We’re not currently clear whether these changes make bladder diseases more likely.” Some studies have shown that urinary symptoms are more common as you get older, with an increasing prevalence of diseases that cause urinary symptoms and ‘symptom complexes’ (collections of symptoms that, for many, have no known cause) such as overactive bladder2.

The bladder also goes through changes in women during pregnancy. Many pregnant women report symptoms in the first and third trimester, although the exact symptoms and their causes differ between these two periods3, as Dr John explains:

“In the first trimester, an increase in the frequency of voiding is common and is attributed to changes in hormones associated with pregnancy. In the third trimester, the weight of the baby pushing on the bladder causes a perceived reduction in bladder capacity and can even be enough to cause urine leakage. Rarely do women report the feeling of only partially voiding the contents of the bladder; when this does occur it’s because downward pressure from the baby can partially close the urethra.”

What causes bladder pain?

Severe bladder pain is different from the chronic bladder disorders that include pain as a symptom. Dr John talks about the most common cause of bladder pain in both men and women:

“In most cases, bladder pain is experienced as a symptom of a urinary tract infection to the bladder called cystitis,” says Dr John. “A large proportion of women experience this at some points in their lives and, in most cases, antibiotics are effective. It occurs in men but prevalence is much higher in women.”

“If pain is chronic and accompanied with symptoms such as blood in the urine, the pain could be associated with a recurrent UTI; interstitial cystitis/bladder pain syndrome; or even bladder cancer. Patients are advised to see their GP if they experience bladder pain and the clinician will diagnose the cause.”

How do you get a bladder infection?

If your bladder swells and feels irritated, you may have a bladder infection, the most common type of UTI. Bacteria tends to be one of the main causes because if it makes its way into your urethra, it can end up causing an infection. UTIs tend to be more prevalent in women because of pregnancy (the baby can make it harder for you to empty your bladder completely) and also because a woman’s urethra is shorter than a man’s, therefore bringing it closer to the vagina and anus where bacteria thrive.

What to do if your bladder hurts and when to see a doctor

If you have severe bladder pain or other concerns about your bladder, Dr John recommends seeking help as soon as you can:

“It’s sensible to speak to a healthcare practitioner (pharmacist or GP) if you notice any sudden changes to toileting habits including changes to the frequency of voiding or waking to void. It’s not normal to leak. It’s also not normal to feel that you’ve not completed emptied, after voiding.”

“Any pain when you’re voiding is not normal and any changes to the colour of your urine (pink, red or brown) warrant medical attention.”

Should you need any further assistance in identifying warning colours, see our article on the different discharge colours.

We hope that you have found our insights on the function of the bladder and the different types of bladder problems beneficial. In the meantime, you may want to practice pelvic floor exercises or use TENA products to help you to enjoy life without worrying about bladder issues and .

Additional sources: