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The bladder

The bladder is a hollow, muscular sac that stores urine (wee or pee). It is located in the pelvis and is part of the urinary system.

As well as the bladder, the urinary system includes two kidneys, two tubes called ureters leading from the kidneys into the bladder, and another tube called the urethra leading out of the bladder. In males, the urethra is a long tube that passes through the prostate and down the penis. In females, the urethra is shorter and opens in front of the vagina (birth canal).

The kidneys produce urine, which travels to the bladder through the ureters. The bladder is like a balloon and expands as it fills with urine. When you are ready to empty your bladder, the bladder muscle contracts and urine is passed through the urethra and out of the body.

There are four main layers of tissue in the bladder.

urotheliumThe innermost layer. It is lined with cells that stop urine being absorbed into the body. These cells are called urothelial cells.
lamina propriaA layer of tissue and blood vessels surrounding the urothelium.
muscularis propriaThe thickest layer. It consists of muscle that contracts to empty the bladder.
perivesical tissueThe outermost layer. Mostly made up of fatty tissue, it separates the bladder from nearby organs.

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This information is reviewed by

This information was last reviewed in February 2020 by the following expert content reviewers: Prof Dickon Hayne, UWA Medical School, The University of Western Australia, and Head, Urology, South Metropolitan Health Service, WA; BEAT Bladder Cancer Australia; Dr Anne Capp, Senior Staff Specialist, Radiation Oncology, Calvary Mater Newcastle, NSW; Marc Diocera, Genitourinary Nurse Consultant, Peter MacCallum Cancer Centre, VIC; Dr Peter Heathcote, Senior Urologist, Princess Alexandra Hospital, and Adjunct Professor, Australian Prostate Cancer Research Centre, QLD; Melissa Le Mesurier, Consumer; Dr James Lynam, Medical Oncologist Staff Specialist, Calvary Mater Newcastle and The University of Newcastle, NSW; John McDonald, Consumer; Michael Twycross, Consumer; Rosemary Watson, 13 11 20 Consultant, Cancer Council Victoria.