What is bladder cancer?
Cancer occurs when cells in the bladder start to grow out of control. Bladder cancer most often begins in the urothelial cells that line the inside of your bladder. Most tumors develop on the inner layer of the bladder. Some can grow into deeper bladder layers. As cancer grows through these layers into the muscle wall, it becomes harder to treat. Urothelial cells are also found in your kidneys and the ureters, the tubes that connect the kidneys to the bladder. Bladder cancer can happen in the kidneys and ureters, too, though much less frequently.
What does your bladder do?
Your bladder is part of your urinary system. The job of the urinary system is to filter waste products from your blood and transport the waste products or urine, out of your body. The diagram below shows the organs of the urinary system.
The urinary system
Most of the urinary tract is lined with a special layer of cells called transitional cells. The primary “machines” in the human filtering system are the two kidneys located close to the backbone and protected by the ribs. The kidneys work independently. They have the significant task of filtering approximately 20% of total blood volume each minute and removing the by-products of digestion and of other body functions.
Once produced, the urine (the filtered waste product) is stored in the central part of the kidney called the renal pelvis. At regular intervals, the renal pelvis contracts and propels the urine through the ureters. These narrow, thin-walled tubes extend from inside the renal pelvis to the bladder. The bladder is a thick-walled structure, consisting of a relatively thin inner layer with a thick muscle covering.
This inner layer or epithelium is made of several layers of cells. The epithelial layer is also called the transitional cell layer. The main function of the bladder is to store urine. For most people, the bladder can hold as much as 1 pint (16 ounces) of urine at a time. It contracts or expands depending on how much fluid is in it. When it contracts following a series of neurological “messages” to the brain and spinal cord, the urine moves through the urethra outside the body.