Get to know the functions of your heart, blood vessels, and blood itself and how they work together to maintain your health.

Your heart is a muscular organ that helps circulate your blood, which delivers oxygen and nutrients to your tissues. There are four chambers and four valves in your heart, and each ensures proper ...

The endocrine system comprises glands and tissues that produce hormones to regulate and coordinate vital bodily functions. This article â the last in an eight-part series â discusses the secondary ...