Why do people have to go to the bathroom?

CEBU, Philippines – When a car engine burns fuel, waste material is left over and passes out the exhaust pipe. Human bodies, which use food for fuel, also produce waste and have an “exhaust” system to get rid of it.

Unlike cars, however, people can store up waste before releasing it. Two big advantages of this are convenience and cleanliness. Another reason is that a constant flow of urine or feces from the body would keep the skin damp all the time, eventually causing soreness and infection.

Going to the bathroom is the normal, healthy way we get rid of waste. If we couldn’t get rid of it, it would soon poison our bodies. A bowel movement discharges material left when food is processed through the stomach and intestine. The waste, or feces, consists of indigestible plant parts, partly burned foods and other chemicals. The strong odor of feces comes from gasses produced by harmless bacteria that live in our intestines.

Urination gets rid of waste left after the kidneys filter and clean our blood. Urine contains excess water, salts, and a chemical combination called urea.

The feeling of having to go to the bathroom is the body’s way of telling us that enough waste is being held. The desire to urinate occurs when our storage tank for urine, the bladder, fills up and starts stretching from the fullness. We know it’s time for a bowel movement when the muscles of the intestines start squeezing down on the bulk. This automatic squeezing, called peristaltic contractions, can be triggered by eating or drinking. That’s why we often “have to go” after a meal.

— from Why Does My Nose Run? By Joanne Settel and Nancy Baggett