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.
The ureter is the tube through which urine moves from the kidney to the bladder. A diagram of a kidney. The renal tubule is part of the filtration system in the nephrons of the kidneys. The distal convoluted tubule helps regulate the pH of the urine by secreting positively charged protons. The kidney contains 4 million nephrons, which are responsible for filtering the blood.