The kidneys are located next to the vertebral column at the end of the rib cage behind the abdominal cavity; one could say that they are located in the region that constitutes the middle of the back.
The kidneys are a pair of reddish brown bean shaped organs about the size of the person's fist with the left kidney occurring at a slightly higher position than the right kidney; the left kidney is situated next to the spleen, while the right kidney is situated near the lower part of the liver.
The kidneys act as the body's purifiers by filtering the blood and removing waste products that are then excreted as urine via the bladder; the filtering units of the kidney are known as nephrons. The things that could go wrong with the kidneys are related to its filtration system often caused due to other complications like diabetes; stones are sometimes formed in the kidneys which may obstruct the flow of urine.
The adrenal glands are located on top of the kidneys which secrete hormones like adrenaline and cortisol dealing with the body's fight or flight reaction during times of stress.