Final answer:
The glomerular filtration rate (GFR) is the rate at which the volume of filtrate is formed by both kidneys per minute, an important measure of kidney function influenced by various pressures within the glomerulus.
Step-by-step explanation:
The rate at which the volume of filtrate is formed is defined as the glomerular filtration rate (GFR). GFR represents the volume of filtrate produced by both kidneys each minute and is a crucial indicator of kidney health. Under resting conditions, the heart pumps about 5 liters of blood per minute, with approximately 20% of that entering the kidneys for filtration. This activity results in an average filtration rate of about 125 mL/min in men and 105 mL/min in women. The produced filtrate amounts to approximately 180 liters per day in men and 150 liters per day in women. However, because 99% of the filtrate is reabsorbed, the actual urine output is much lower, typically 1-2 liters per day.
The GFR is influenced by factors such as hydrostatic pressure and colloid osmotic pressure, and despite fluctuations in systemic blood pressure, the kidneys can maintain a relatively constant GFR due to their autoregulatory capabilities. The filtration fraction (FF) is the ratio of the GFR to the renal plasma flow (RPF) which indicates the proportion of plasma that is filtered into Bowman's capsule.