Final answer:
The statement is true; the kidneys are retroperitoneal organs located just below the diaphragm and the posterior body wall. They are well protected and receive a significant portion of the body's cardiac output for blood filtration.
Step-by-step explanation:
The statement that the kidneys lie in the retroperitoneal cavity near the posterior body wall, just below the diaphragm is true. Each kidney is found on either side of the spine, between the parietal peritoneum and the posterior abdominal wall. Protected by several layers, including muscle, fat, ribs, and a tough renal fascia, the kidneys are well guarded within this space. In terms of size, they are roughly comparable to a person's fist, with slight variations between individuals and between males and females.
The kidneys are highly vascularized, receiving about 25 percent of the cardiac output when the body is at rest. This allows them to efficiently filter blood and produce urine. Anatomically, the right kidney is typically slightly lower and smaller due to the presence of the liver, while the left kidney is positioned slightly higher and is a bit larger.