What substance do humans excrete through sweat?

Humans excrete a combination of water, salts, and ammonia through sweat, which is primarily produced by sweat glands in the skin. This process plays a vital role in thermoregulation, helping to cool the body when it becomes too hot.

Water is the main component of sweat, constituting approximately 99% of its content, which aids in maintaining hydration while facilitating temperature control. The salts present, such as sodium chloride, are electrolytes that help regulate fluid balance and are vital for various bodily functions. Ammonia is a waste product from protein metabolism, and while it is not present in large quantities in sweat compared to water and salts, it is still a component.

This combination of substances effectively helps remove excess water and regulate electrolyte balance in the body, aligning with the body's need to maintain homeostasis.