The nephron is an excretory unit of the kidney that regulates water concentration and soluble substances by blood filtering, re-absorption of what is required, and excretion of the rest as urine. Filtration is the movement triggered by the blood flow and pressure. Filtration commonly takes place in the Bowman’s capsule and the glomerulus where glucose, water, minerals, amino acids, nitrogenous wastes, hormones and bicarbonate ions are filtered from the blood. Re-absorption is the movement through which required substances from the glomerular filtrate are placed back into the blood. The substances are extracted from the tubular fluid, transported into the connective tissues surrounding the nephron (renal interstitium), and then back into the bloodstream. This movement occurs through active transport, diffusion, and osmosis.