There are two kidneys, each about the size of a fist
The kidneys located on either side of the spine at the lowest level of the rib cage.
Due to the asymmetry caused by the liver, the right kidney is generally slightly smaller and lower than the left.
Each kidney weighs 125 to 170 grams (g) in males and 115 to 155 g in females.
The kidneys are relatively small organs, but they receive up to 25 percent of the heart's output
Each kidney contains up to a million functioning units called nephrons.
A nephron consists of a filtering unit of tiny blood vessels called a glomerulus attached to a tubule.
About 80% of blood plasma escape from the blood vessels to the glomerulus.
Around 180 litter per day enter the glomerulus.
Only about 2 litters of 180 litters eliminated as urine, the rest is reabsorbed / return back to blood stream