Urination. It is something we all do, several times a day, without even thinking about it. It is just a part of our daily routine. But what, exactly, causes the urge to urinate? How does the body know when the bladder has enough urine collected and that it is time to urinate?
The kidneys are the part of the urinary system that are responsible for filtering waste and excess water out of blood. The end product of this process is urine. According to the National Institute of Diabetes and Digestive and Kidney Diseases, the bean-shaped kidneys are fist-sized organs located in the lower back. As the kidneys collect urine, it travels down tubes and into the bladder.
The bladder is a balloon-shaped muscular organ that sits low in the abdomen. The tubes that drain urine from the kidneys exit into the bladder. The bladder is hollow and slightly elastic, so as it fills with urine it expands. According to the National Institutes of Health, a healthy bladder can hold up to 2 cups of urine comfortably for several hours. When the bladder approaches its maximum capacity, it sends signals to the brain, letting the body know that it is time to urinate.
When the brain receives notice from the nerves in the bladder that the bladder is full, it creates the urge to urinate. Urine is kept in the bladder by a ring of muscle that surrounds the urethra (the tube from which urine travels from the bladder to exit the body). When we have the urge to urinate and we are ready to urinate, the brain sends a signal to this muscle to relax and allow urine to flow out of the body. At the same time, it sends a message to the bladder muscles to tighten, squeezing urine out of the bladder and down the urethra.
Urge incontinence is a condition that causes a person to involuntarily release urine when the urge to urinate strikes. It can also cause a person to feel an extreme sudden urge to urinate, which is abnormal. In most people, the urge to urinate builds over time. According to the National Institutes of Health, the exact cause of urge incontinence is unknown in most cases. Women and elderly people are the most likely part of the population to experience urge incontinence, also known as an overactive bladder.
Diseases Affecting Urination
There are several diseases and conditions that can affect the ability to urinate. The most serious of these is bladder or kidney cancer. Kidney disease is another serious and potentially deadly disease that can affect the ability to urinate properly. Other conditions that can affect urination are urinary tract infections, kidney stones and diabetes. If you have difficulty urinating or have changes in your urinary habits, consult your doctor immediately.