What is meant by renal perfusion?

Renal perfusion refers to the process of blood flow to the kidneys. Adequate perfusion is crucial for the kidneys to perform their essential functions, including filtering blood, removing waste products, and regulating fluid and electrolyte balance. The kidneys receive a significant amount of blood flow relative to their size, typically accounting for about 20-25% of the cardiac output. This high level of blood flow ensures that the kidneys can effectively filter and excrete waste while also maintaining homeostasis in the body.

Other options relate to different processes associated with kidney function or outcomes of renal physiology but do not define renal perfusion specifically. Urine flow pertains to the output of the urinary system rather than the input in terms of blood supply. Fluid retention is a symptom or result of renal function issues, rather than a direct description of blood flow. Hormone secretion involves regulatory mechanisms by the kidneys, but again, it is not about blood flow. Understanding that renal perfusion focuses specifically on blood supply helps distinguish it from these other aspects of renal physiology.