The endocrine system is a network of glands and organs that uses chemical messengers called hormones to regulate metabolism, growth, reproduction, heart rate, blood pressure, and sleep-wake cycles.

The tongue helps with eating, tasting, swallowing, speaking, and breathing. A healthy tongue is pink, but changes in its appearance can signal health issues. Essential to the tongue’s anatomy are ...

The lens focuses light and images onto the retina to help you see clearly. As you age, your lens may lose flexibility and become cloudy, leading to presbyopia and cataracts. The lens in your eye bends ...