The bladder holds urine that is produced by the kidneys. It is located in the lower pelvic area of the human body. The bladder expands as it fills, and contracts to expel urine through the urethra.Johns Hopkins University : Anatomy and Physiology of the Bladder

1. Transitional Epithelium: Layer of cells that lines the bladder that is in contact with urineJohns Hopkins University : Anatomy and Physiology of the Bladder
2. Lamina propria: Consists of blood vessels and connective tissueJohns Hopkins University : Anatomy and Physiology of the Bladder
3. Muscularis propria; Outer wall of the bladder, consisting of muscular tissue Johns Hopkins University : Anatomy and Physiology of the Bladder

There are several factors that can impact the health of the bladder such as the amount of water consumed, diet, medication and disease.Department of Health and Aging: Healthy Bladder Habits Providence Health & Services: Tips to Keep Your Bladder Healthy

Health problems that involve the bladder include bladder cancer, cystitis, incontinence , urinary tract infection, bladder stones and bed wetting.MedlinePlus: Bladder Diseases Mayo Clinic: Bladder Stones Mayo Clinic: Bed Wetting

Approximately 55,000 cases of bladder cancer are diagnosed annually, making this cancer the ninth most common cancer in women and the fourth most common cancer among men. If detected early, it has a 90% five-year survival rate. Treatment usually involves surgery, but may also include chemotherapy and radiation.The cancer Information Network: Facts About Bladder Cancer