MEDICAL PHYSIOLOGY

Detailed explanation-1: -Renal blood flow (RBF) of about 1200 ml/min is well maintained (autoregulated) at blood pressures of 80 to 180 mm Hg. The cortex requires about 80% of blood flow to achieve its excretory and regulatory functions, and the outer medulla receives 15%.

Detailed explanation-2: -Renal blood flow (RBF) is about 1 L/min. This constitutes 20% of the resting cardiac output through tissue that constitutes less than 0.5% of the body mass! Considering that the volume of each kidney is less than 150 mL, this means that each kidney is perfused with over 3 times its total volume every minute.

Detailed explanation-3: -In total, about 20-25% of the total cardiac output ends up flowing through the kidneys. That ends up being about 400ml/100g tissue/min, or about 1000ml per minute; i.e. approximately eight times more than the brain.

Detailed explanation-4: -The amount of the filtrate formed by the kidneys per minute is called glomerular filtration rate (GFR). GFR in a healthy individual is approximately 125 ml/minute, i.e., 180 litres per day.