Mad About Science: Urine

By Brenden Bobby
Reader Columnist

I love writing about gross stuff, and there are few things that gross people out more than things that come out of the human body. However, it’s important to know what comes out of us. In fact, keeping an eye on color and consistency is one of the best ways to make sure you’re staying healthy, otherwise… urine trouble!

Whizzing by to the facts, the urinary tract starts at your kidneys, which are nestled just below your ribcage. Your kidneys are absolutely vital to keeping you alive, as they are natural filters that pull toxins from your bloodstream and convert them into urine. They do this by pushing your blood through a number of tiny vessels called the glomerulus, which has openings small enough for waste molecules and water to pass through while deflecting larger molecules like protein and blood cells. Over time, your kidneys can collect calcium deposits to form kidney stones. Sometimes, one of these kidney stones can become dislodged and enter the next stage of the urinary tract, the ureter, which is a thin tube of muscle that acts like the drain of a roof gutter.

Having suffered from a kidney stone (thanks, Celiac disease), I can tell you that this is just about the worst pain you can possibly imagine. The kidney stone will block the ureter and cause a backup of urine between the blockage and the kidney. Your kidneys won’t stop the filtration process just because there’s a blockage down the line, which increases pressure on the ureter. Depending on how much water you drink in a day, your kidneys can create up to half a gallon of urine in a 24-hour period. The ureter, meanwhile, is about 0.14 inches in diameter. I’ll let you do the painful math on that one.

In some cases, small kidney stones will simply continue on the magical journey of human waste by exiting the ureter and entering the bladder, which is a hollow organ that expands as it fills with urine and contracts when it’s empty. As the bladder reaches capacity, a specialized set of nerves will send a signal to the brain, telling you to find a bathroom immediately. The urine exits through the urethra, and where it goes from there depends entirely on you.

You would think that something that comes racing out of your body and smells funny would be a bacterial conduit, but urine actually has less bacteria in it than tap water. Now, I’m not advocating for the Bear Grylls diet unless survival demands it — that’s just insane — but urine is sterile because the bacteria are filtered out at your kidneys and processed as solid waste later. If there is bacteria in your urine, then it’s likely that you’re suffering from a urinary tract infection, a kidney stone or some kind of kidney disease. If you think you have one of these, stop reading this article and call a doctor.

Being a human and having lived long enough to know how to read, you’ve probably noticed that your urine has changed colors throughout your life. The color of your urine can tell you a lot about your health. If it’s fairly clear, it’s probably because you’ve been drinking a lot of water, which is good. If it’s darker, you could probably use some more water. If it’s pink, it could mean a few different things: beets can cause pink or red urine, but so can certain antibiotics and blood, which requires a doctor’s visit. If it’s blue or green, it’s most likely from ingesting lots of drinks with blue dye. Orange or brown urine happens when you have an excess of vitamin B2 in your bloodstream or if there’s a problem with your liver — in either case, it’s good to ask a doctor.

All sorts of stuff can cause quirky things to happen with our urinary tract. In men, an enlarged prostate can pinch the urethra and cause discomfort or incontinence. In women, pregnancy will often cause increased trips to the loo — after all, you’re peeing for two. Vastly increased need to hit the head can be indicative of diabetes, as glucose builds up in your bloodstream and your kidneys kick into overdrive to filter it out.

In the event of renal failure and some cancers, people need to have their kidneys removed or disconnected. While it might sound awesome to save all that time never having to use the latrine again, it’s imperative that you go onto dialysis at this point. Dialysis does what your kidneys did by filtering waste out of your blood with a machine, then pumping the clean blood back into your bloodstream. This takes about four hours a day, three times a week for as long as you are without kidneys. It’s hugely expensive and not a long-term solution, as the life expectancy is between five to 10 years.

Got more questions? Hit the health section at your local library or give your doctor a ring.