Doctors can often see a large hiatus hernia on a chest x-ray. Otherwise, people are given barium in a liquid before x-rays are taken (barium swallow). The barium outlines the esophagus, making abnormalities easier to see. Hernias can also be seen during an upper endoscopy.
The kidneys filter the blood to remove wastes and produce urine. The ureters, urinary bladder, and urethra together form the urinary tract, which acts as a plumbing system to drain urine from the kidneys, store it, and then release it during urination.
Urea waste. Urea is excreted by the kidneys, and is less toxic than ammonia and can be transported in the blood from the liver where it is formed from ammonia. This molecule is very small, diffuses easily across cell membranes and requires no specialized transport system.