<P> The nephron is the structural and functional unit of the kidney . Each adult kidney contains around one million nephrons . The nephron utilizes four processes to alter the blood plasma which flows to it : filtration , reabsorption , secretion , and excretion . Via one or more of these mechanisms , the kidney participates in the control of the volume of various body fluid compartments , fluid osmolality , acid - base balance , various electrolyte concentrations , and removal of toxins . Filtration occurs in the glomerulus : one - fifth of the blood volume that enters the kidneys is filtered . Examples of substances reabsorbed are solute - free water , sodium , bicarbonate , glucose , and amino acids . Examples of substances secreted are hydrogen , ammonium , potassium and uric acid . Examples of substances that are excreted are urea , ammonium , and uric acid . The kidneys also carry out functions independent of the nephron . For example , they convert a precursor of vitamin D to its active form - calcitriol - and synthesize the hormones erythropoietin and renin . </P>
<P> The nephron is the structural and functional unit of the kidney . Each adult kidney contains around one million nephrons . The nephron utilizes four processes to alter the blood plasma which flows to it : filtration , reabsorption , secretion , and excretion . Via one or more of these mechanisms , the kidney participates in the control of the volume of various body fluid compartments , fluid osmolality , acid - base balance , various electrolyte concentrations , and removal of toxins . Filtration occurs in the glomerulus : one - fifth of the blood volume that enters the kidneys is filtered . Examples of substances reabsorbed are solute - free water , sodium , bicarbonate , glucose , and amino acids . Examples of substances secreted are hydrogen , ammonium , potassium and uric acid . Examples of substances that are excreted are urea , ammonium , and uric acid . The kidneys also carry out functions independent of the nephron . For example , they convert a precursor of vitamin D to its active form - calcitriol - and synthesize the hormones erythropoietin and renin . </P>
where does all filtration take place in the kidneys
where does all filtration take place in the kidneys
glomerulus
glomerulus