The urinary tract (also known as the urinary or renal system) is your body’s dedicated drainage system. Its primary job is to filter your blood, remove liquid waste (urine), and keep your body’s chemicals and water in a healthy balance.
For your body to function normally, every part of the urinary tract must work in perfect synchronisation.
The urinary tract is composed of several specialised organs: two kidneys, two ureters, one bladder, and one urethra. In men, the prostate also plays a role in the lower urinary tract.
1. Kidneys: The Body’s High-Tech Filters
Your kidneys are two bean-shaped organs located on either side of your spine, just below the rib cage. Each is roughly the size of your palm—about 12 cm long and weighing 150g.
Asymmetry: Interestingly, the right kidney sits slightly lower than the left to make room for your liver.
The Power of One: While most people are born with two kidneys, approximately 1 in 1,000 people are born with only one. Most “solitary kidney” patients lead completely normal, healthy lives.
How Kidneys Produce Urine
Your kidneys are incredibly efficient. They filter your entire 5-liter blood supply roughly 35 times a day.
The Process: Blood enters the kidneys through tiny filtering units called nephrons, which contain microscopic filters called glomeruli.
Reabsorption: Although your kidneys filter about 180 litres of fluid daily, they reabsorb most of it (178 litres) back into the bloodstream.
Output: Therefore only about 2 liters of waste and extra water leave the body as urine each day.
2. Ureters: The Transport Tubes
The ureters are thin, muscular tubes that connect the kidneys to the bladder. Through constant, wave-like muscle contractions (peristalsis), they move urine away from the kidneys to prevent backup or infection.
3. Bladder: The Storage Reservoir
Located in the pelvis, the bladder is a hollow, balloon-like muscular organ. Its primary role is to store urine until you are ready to release it.
Capacity: The average adult bladder holds about 300–400 ml of urine—roughly the size of a standard soda can. Yes, the human bladder is quite small.
The Signal: When the bladder reaches its limit, nerves send a signal to your brain. While you cannot control your kidneys, you can voluntarily control the urinary sphincter to decide when to empty your bladder.
4. Urethra: The Exit Path
The urethra is the tube that carries urine from the bladder out of the body.
In Men: The urethra is longer and travels through the penis.
In Women: The urethra is much shorter and ends at the vulva.
The UTI Connection: Because the female urethra is shorter and closer to the rectum, it is easier for bacteria to reach the bladder, which is probably why women are more prone to Urinary Tract Infections (UTIs).
5. Prostate (Men Only)
The prostate is a walnut-sized gland located just below the bladder. While it is primarily part of the reproductive system—adding fluid to semen—it surrounds the urethra. If the prostate becomes enlarged, it can squeeze the urethra and cause difficulty with urination.
Kidneys filter blood and create urine.
Ureters transport urine downward.
The Bladder stores urine and expands.
The Urethra carries urine out of the body.
Maintaining a healthy urinary tract is essential for preventing kidney disease and infections. Drinking plenty of water and practicing good hygiene are the best ways to keep this complex system running smoothly.
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