þvagblöðrum

Þvagblöðrum, known scientifically as the urinary bladder, is a hollow, muscular organ that sits in the pelvis. Its primary function is to store urine produced by the kidneys before it is eliminated from the body through the urethra. The bladder is made up of smooth muscle tissue called the detrusor muscle, which can expand to hold a significant amount of urine and contract to expel it.

The bladder has a capacity that varies among individuals but typically holds around 400 to 600 milliliters of urine. As the bladder fills, stretch receptors within its walls send signals to the brain, creating the sensation of needing to urinate. This sensation becomes more urgent as the bladder continues to fill.

When the decision to urinate is made, the brain signals the detrusor muscle to contract and the internal urethral sphincter to relax, allowing urine to flow out of the bladder and into the urethra for excretion. The external urethral sphincter is under voluntary control, allowing individuals to consciously decide when to urinate.

Disruptions in bladder function can lead to various conditions, such as urinary incontinence, where there is an involuntary loss of urine, or urinary retention, where the bladder cannot be emptied completely. These issues can be caused by a range of factors including nerve damage, infections, or structural problems.