<P> The four mechanisms used to create and process the filtrate (the result of which is to convert blood to urine) are filtration, reabsorption, secretion and excretion . Filtration occurs in the glomerulus and is largely passive: it is dependent on the intracapillary blood pressure . About one - fifth of the plasma is filtered as the blood passes through the glomerular capillaries; four - fifths continues into the peritubular capillaries . Normally the only components of the blood that are not filtered into Bowman's capsule are blood proteins, red blood cells, white blood cells and platelets . Over 150 liters of fluid enter the glomeruli of an adult every day: 99% of the water in that filtrate is reabsorbed . Reabsorption occurs in the renal tubules and is either passive, due to diffusion, or active, due to pumping against a concentration gradient . Secretion also occurs in the tubules and is active . Substances reabsorbed include: water, sodium, chloride, glucose, amino acids, lactate, magnesium, calcium, phosphate, uric acid, and bicarbonate . Substances secreted include urea, creatinine, potassium, hydrogen, and uric acid . Some of the hormones which signal the tubules to alter the reabsorption or secretion rate, and thereby maintain homeostasis, include (along with the substance affected) antidiuretic hormone (water), aldosterone (sodium, potassium), parathyroid hormone (calcium, phosphate), atrial natriuretic peptide (sodium) and brain natriuretic peptide (sodium). A countercurrent system in the renal medulla provides the mechanism for generating a hypertonic interstitium, which allows the recovery of solute - free water from within the nephron and returning it to the venous vasculature when appropriate . </P> <P> Some diseases of the nephron predominantly affect either the glomeruli or the tubules . Glomerular diseases include diabetic nephropathy, glomerulonephritis and IgA nephropathy; renal tubular diseases include acute tubular necrosis and polycystic kidney disease . </P> <P> The nephron is the functional unit of the kidney . Each nephron is composed of a renal corpuscle, the initial filtering component; and a renal tubule that processes and carries away the filtered fluid . </P> <P> The renal corpuscle is the site of the filtration of blood plasma . The renal corpuscle consists of the glomerulus, and the glomerular capsule or Bowman's capsule . The renal corpuscle has two poles--a vascular pole and a urinary pole . </P>

Nephron is related to which of the following system of human body