Urinary system
Bladder
The bladder is a stretchy, muscular bag that stores urine until you pass it. It can hold around 400–600 ml and signals when it needs emptying.
What it is
The bladder is a hollow, muscular organ in the pelvis that collects urine from the kidneys.
Where it is
In the lower pelvis, behind the pubic bone.
What it does
Stores urine made by the kidneys and releases it, under conscious control, through the urethra when you go to the toilet.
How it works
Urine drains continuously from the kidneys into the bladder, which stretches to hold it. When it is comfortably full, nerves signal the urge to go; the bladder muscle then contracts and the outlet relaxes to empty it.
When things go wrong
Common conditions affecting the bladder
- Urine infections (cystitis)
- Urinary incontinence
- Overactive bladder
- Bladder cancer
Education and reference only. This explains the anatomy in plain terms and is not a diagnosis. Sudden severe symptoms — such as severe chest pain, breathlessness or collapse — are an emergency; call 999.
Looking after it
Keeping your bladder healthy
Staying hydrated, not smoking (a major bladder-cancer risk), pelvic-floor exercises, and getting blood in the urine checked promptly all protect the bladder.
Did you know?
An interesting fact
The bladder can stretch to hold around half a litre of urine, and its muscular wall is called the detrusor.
Answers
Bladder: frequently asked questions
What does the bladder do?
The bladder stores urine from the kidneys and releases it when you go to the toilet.
Is blood in the urine serious?
Visible blood in the urine should always be checked by a doctor, as it can be a sign of bladder or kidney problems, including cancer, even if there is no pain.
The urinary system
Related organs
Sources
Where this is drawn from
- NHS — Anatomy and body systems
- Gray's Anatomy for Students
- TeachMeAnatomy / TeachMePhysiology
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