Final answer:
True, the fluid intake normally equals fluid output to maintain fluid balance and homeostasis in the body, with the kidneys and hormones like ADH regulating this equilibrium.
Step-by-step explanation:
The principle of fluid balance states that there should be equilibrium between fluid intake and fluid output in the body. This is indeed true. To achieve homeostasis, the body regulates water balance, ensuring that the amount of water consumed through drinking fluids, eating solid foods, and generated through metabolic processes is equal to the amount of water expelled through urine, sweat, feces, and other forms of excretion.
The kidneys play a crucial role in this process by adjusting urine concentration with the help of hormones like ADH (antidiuretic hormone), which increases water reabsorption to conserve water during dehydration, or by making urine more dilute to expel excess water when necessary.