þvagblöðru

The þvagblöðra, or urinary bladder, is a hollow, muscular organ in humans and other animals that stores urine. It is part of the urinary system and is located in the pelvis, behind the pubic bone. The bladder is connected to the kidneys by two tubes called ureters, which transport urine from the kidneys to the bladder. Urine leaves the bladder through a single tube called the urethra, which empties to the outside of the body.

The bladder is capable of expanding to hold a significant amount of urine. The walls of the bladder are made up of layers of smooth muscle, which contract to expel urine during urination. The inner lining of the bladder is a specialized type of epithelium called transitional epithelium, which can stretch and recoil as the bladder fills and empties.

The process of urination, also known as micturition, is controlled by a complex interplay of voluntary and involuntary nerve signals. When the bladder fills with urine, stretch receptors in its walls send signals to the brain. The brain then signals the bladder muscles to contract and the sphincter muscles surrounding the urethra to relax, allowing urine to be expelled.

Disorders of the urinary bladder can include infections, inflammation, incontinence (inability to control urination), and bladder cancer. These conditions can significantly impact a person's quality of life and may require medical intervention.