Final answer:
Water constitutes approximately 50-70% of an adult human's body weight. This percentage varies with age and the water content differs among various organs. Water is essential for bodily functions and is distributed both inside cells (intracellular) and outside cells (extracellular).
Step-by-step explanation:
Water comprises a significant portion of the human body, constituting about 50-70% of an adult's body weight. The percentage of body water varies throughout the stages of life, with infants having about 75%, adults ranging from 50-60%, and the elderly potentially having as low as 45%. Additionally, water content differs among various organs; for instance, the brain and kidneys are made up of 80-85% water, while teeth contain only 8-10%.
In terms of body weight, it's estimated that almost 70-80% of the human body consists of fluids, majorly suspended in water. This water is essential, as it is the medium for all intracellular and extracellular reactions. The role of water extends beyond just composition—it is also vital for processes like osmosis, which maintains the balance of fluids across cell membranes.
The distribution of water in the body is both intracellular and extracellular. Intracellular fluid accounts for about 50% of the body weight in lean individuals, while extracellular fluids represent about 20% of body weight, subdivided into interstitial fluid and blood plasma.