OK, so that’s not exactly true, which may be why the children’s book of the same name didn’t do nearly as well as its predecessor. Still, peeing is of great importance — it is number one, after all — and there’s probably a lot that you do and don’t know about it.

For example, you might not know what gives urine its particular color, but you most likely know that public urination is acceptable for dogs and not for humans. I could start off this column with some humorous personal anecdotes, but I don’t want to be scolded for “unprofessionalism,” so let’s just dive right in:

My pee is yellow

This is a good thing! You probably knew that urine contains some of your body’s “waste” products, and it is one particular waste product that results in this coloration.

You see, when red blood cells become old, they must be broken down. Heme, an important component of red blood cells that carries iron, is degraded as part of this process. There are several steps in heme degradation. One of the final breakdown products is a pigment called urobilin, which ends up in the kidney and makes urine look yellow.

Interestingly, some of the other breakdown products from heme give bruises and feces their characteristic colors as well. If your urine is not yellow, there might be a good explanation for this (some medications will do this). However, if it is unexpected or if you see any actual blood (red) in your urine: that is bad, so please go see a doctor.

A place for everything

We are born with some abilities necessary to our survival (ex. urination), but controlling our natural gifts does take time and effort (and a lot of laundry). The pee has one pathway by which it must exit your body. To perhaps oversimplify, the urine is stored in a pouch (the bladder) and must past one doorway (the internal sphincter) and another doorway (the external sphincter) before it makes it into the toilet (hopefully). The path it follows from the bladder to the outside world is called the urethra. The female urethra is about 1.6 inches long, whereas that of males is around 7.1-8.7 inches long. (Can you see why women might get more urinary tract infections?)

Anyway, when your bladder fills up with 150mL of urine, you start feeling like you have to go. By 400-500mL, you really feel like you have to go. Once you’ve made it to the bathroom, you tell your external sphincter to relax, which is then followed by the internal sphincter relaxing. As the pee starts coming out, your bladder then starts contracting and voila!

I am lost in the desert and have no water.

We’ve all heard those miraculous survival stories and wondered what we would do in those situations. Would I rather die or drink my own pee? How long would I last without another source of water? Urine is mostly but not entirely sterile. Unless you have an infection, drinking your urine probably won’t hurt you. In fact, some people drink it for healing purposes or sexual activity, but I won’t recommend that you do this. The U.S. Army also does not support the drinking of urine, even though folklore suggests that it might extend your survival by a day or two. Although drinking it the first time around might not result in permanent damage, drinking it over and over instead of drinking water is most certainly harmful. Not only would the potentially toxic waste products in urine build up, but so would the salts, which might result in further dehydration.

My pee tastes …

I really couldn’t tell you. But if it tastes sweet, you might have diabetes. This is actually how physicians used to arrive at this diagnosis. In which case, go to the doctor!

Dorothy Chyung is a second year M.D. student at Weill Cornell Medical College. What’s Up, Doc?, a column featuring a rotating cast of medical students, appears alternate Fridays this semester. She may be reached at doc2011@med.cornell.edu.