Final answer:
The statement is false as not all water in the human body comes from dietary sources; a portion is produced during cellular metabolism. Water balance is maintained through intake, loss, and regulation by the kidneys.
Step-by-step explanation:
The statement 'All water in the human body comes from dietary sources' is false. While most water intake comes through the digestive tract via liquids and food, a significant proportion, approximately 10 percent of water available to the body, is generated internally at the end of aerobic respiration during cellular metabolism. Furthermore, water is an indispensable component for maintaining homeostasis in the body, playing several roles in human functioning such as in the regulation of body temperature, as a solvent for biochemical reactions, and as a transport medium for nutrients and waste materials.
Water is constantly lost through various routes such as urine, sweat, and insensible water loss through skin and respiration. The kidneys play a crucial role in regulating water balance, conserving water when the body is dehydrated and expelling excess water if necessary. Therefore, not all water in the body originates from what we eat and drink; it is also a byproduct of metabolic processes.