What Is the Difference Between the Kidneys and the Bladder?

The kidneys and the bladder are both part of the urinary system, but they serve very different purposes. Understanding the difference between them helps explain how your body removes waste and stays in balance.

The kidneys are two bean-shaped organs located on either side of your spine, just below the ribcage. Their main job is to filter your blood, removing waste products, extra water, and excess salts. They produce urine as a way to carry these unwanted substances out of the body. Each day, your kidneys filter around 180 liters (48 gallons) of blood and produce about 1 to 2 liters (1 to 2 quarts) of urine.

Once the urine is formed, it flows from the kidneys through narrow tubes called ureters and enters the bladder.

The bladder is a hollow, muscular organ located in the lower abdomen. It acts as a storage tank for urine. As urine flows in, the bladder stretches and expands. It can hold about 400 to 600 milliliters (13 to 20 ounces) of urine comfortably. When the bladder is full, signals are sent to the brain, and you feel the urge to urinate.

In short, the kidneys make the urine, and the bladder stores it until it is convenient and safe to release it through the urethra.

These two organs work together in a smooth and coordinated way. The kidneys manage what leaves your body, and the bladder controls when it leaves. Both are essential for removing waste and maintaining a healthy balance of water and minerals in your system.

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