| wrinkles | — | skin | Human | |
| Widespread degeneration of glomerular blood vessels | — | renal vasculature | Human | |
| white matter volume decreases | — | white matter | Human | |
| weaker digestive tract muscle contractions | — | alimentary system, smooth muscle | Human | |
| weakening of intestinal wall | — | large intestine | Human | |
| wall increases in thickness | — | left ventricle | Human | |
| volume of perivascular space around thymus increases | — | thymus | Human | |
| volume of hematopoietic bone marrow decreases | — | bone marrow | Human | |
| Vitamin A absorption unchanged | — | plasma | Human | |
| viscoelastic modulus of brain tissue decreases | — | brain | Human | |
| ventilatory rate at maximum exertion decreases | — | lung | Human | |
| Venous blood sugar slightly increased | — | plasma | Human | |
| vasodilation induced by acetylcholine or sodium reduced | — | renal vasculature | Human | |
| Variations in fat mass | — | adipose tissue | Human | |
| Variations in body weight | — | whole body | Human | |
| variability in clearance of hepatically metabolized drugs | — | liver | Human | |
| vaccination antibody response is impaired | — | immune system | Human | |
| urine concentrating capacity decreases | — | renal tubule | Human | |
| triglyceride levels increase | — | blood | Human | |
| transport maximum for glucose declines | — | renal tubule | Human | |
| transporter activity decreases | — | blood brain barrier | Human | |
| Transmission of visible light through eye lenses decreases | — | lens | Human | |
| Total body water decreases | — | whole body | Human | |
| Total body potassium declines | — | whole body | Human | |
| thymus involution | — | thymus | Human | |