Which of the following is not involved in chemical digestion?

A. Diuretics increase urine output by inhibiting the reabsorption of water and sodium in the kidneys, which leads to increased water loss. This action is opposite to water conservation, making this the correct answer.

B. The counter current exchange system in the kidneys helps conserve water by maintaining a high osmolarity in the medulla, which facilitates the reabsorption of water in the collecting ducts. This system contributes to water conservation.

C. The collecting duct plays a crucial role in water reabsorption. Antidiuretic hormone (ADH) increases the permeability of the collecting duct to water, allowing more water to be reabsorbed back into the bloodstream, contributing to water conservation.

D. The counter current multiplier is a mechanism in the loop of Henle that creates a concentration gradient in the kidney medulla, which is essential for water reabsorption in the collecting ducts. It contributes to water conservation.

A. Metabolic water; cutaneous transpiration: Metabolic water refers to the water produced during metabolic processes within the body. However, most body water intake comes from drinking fluids, not metabolic water.

B. Drinking; cutaneous transpiration and expired air: While drinking is indeed the main source of water intake, the greatest loss of water from the body is through urine, not cutaneous transpiration and expired air.

C. Drinking; radiation: While drinking is the primary source of water intake, radiation is not a significant way the body loses water.

D. Drinking; urine: Drinking fluids is the main source of water intake, and urine excretion is the primary way the body loses water.