Final answer:
The kidneys are located in the retroperitoneal space, protected by the posterior abdominal wall and receive significant blood flow for filtration. Each kidney contains nephrons to filter blood and form urine.
Step-by-step explanation:
The kidneys form a paired organ system located in the retroperitoneal space. This space is situated between the parietal peritoneum and the posterior abdominal wall, providing the kidneys with protection from the surrounding muscle, fat, and ribs. Each kidney is approximately the size of a fist, with the male kidney being typically a bit larger than the female kidney.
The kidneys are highly vascularized organs, receiving about a quarter of the cardiac output when the body is at rest, which underscores their importance in filtering blood. The kidneys' primary function is to filter metabolic wastes from the blood, concentrate them, and form urine, which is then collected in the bladder. The filtering is done through more than a million tiny units within each kidney called nephrons, with all the blood in the body being filtered approximately 60 times a day.
These organs are not only crucial for excretion but also play a vital role in regulating various physiological processes such as blood pressure and electrolyte balance. The right kidney is generally positioned slightly lower than the left due to the presence of the liver, which causes an asymmetrical layout within the abdominal cavity.