A UTI is when bacteria gets into your urine and travels up to your bladder. As many as 8 in 100 of girls and 2 in 100 of boys will get UTIs. Young children have a greater risk of kidney damage linked to UTI than older children or adults.
The “urinary tract” is the organs in your body that make, store, and get rid of urine, one of the waste products of your body. Urine is made in the kidneys and travels down to the bladder through the ureters (the tubes that join them). The kidneys make about 1½ to 2 quarts of urine a day in an adult, and less in children, depending on their age. In children, the bladder can hold 1 to 1½ ounces of urine for each year of age. For example, a 4-year-old child’s bladder can hold 4 to 6 ounces—a little less than a cup.
The bladder stores the urine until it is emptied through the urethra, a tube that links the bladder to the skin, when you urinate. The urethra opens at the end of the penis in boys and in front of the vagina in girls.
The kidneys also balance the levels of many chemicals in the body (sodium, potassium, calcium, phosphorous and others) and check the blood’s acidity. Certain hormones are also made in the kidneys. These hormones help control blood pressure, boost red blood cell production and help make strong bones.
Normal urine has no bacteria in it, and the one-way flow helps prevent infections. Still, bacteria may get into the urine through the urethra and travel up into the bladder.