Step-by-step explanation:
The reason for the fact that the blood is usually not found in the urine of a healthy person is:
Kidneys are located in back just below the lowest rib. Each kidney is about 4.5 inches long and weighs about 5 ounces. Each kidney contains about a million functional units called nephrons.
Every nephron consists of glomerulus and tubule. Each glomerulus unit functions as tiny filter. Blood in the body passes through these glomerulus, that retains the blood cells and large biomolecules like proteins in circulation while allowing fluid and some small molecules to pass through to tubule.
As the fluid flows through tubules, much of the volume of the liquid is absorbed back in bloodstream. The tubules then join to form collecting system of each kidney. By this point, the concentrated fluid has all characteristics of the urine.
If blood occur in the urine, that means the nephrons cannot function properly which can lead to kidney damage.