Isotopes when written out are common nouns, and should begin with the uncapitalized element name, followed by a hyphen (not an em dash or en dash) and then the mass number. Examples are carbon-14 and uranium-235.
The central region of the kidney contains the renal pelvis, which is located in the renal sinus, and is continuous with the ureter. The renal pelvis is a large cavity that collects the urine as it is produced. The periphery of the renal pelvis is interrupted by cuplike projections called calyces.
Urine is produced in microscopic structures in the kidney called nephrons. Each kidney has many millions of nephrons. The glomerulus filters blood and produces glomerular filtrate. This filtrate contains water, glucose, salts and urea. Large molecules such as protein are too large to fit through the blood capillary walls. The bowman's capsule collects the filtrate and it enters the tubules. All glucose is reabsorbed immediately into the blood capillaries.