The nervous system is a complex network of specialized tissues that regulates thoughts, emotions, actions, sensations, and body functions. It has two major divisions: the central nervous system and the peripheral nervous system.
The endocrine system comprises a number of glands that produce hormones with a varied array of vital functions. Hormones control or regulate the development or function of structures throughout the body.
If you've ever laced your fingers together, turned your palms away from you, bent your fingers back and heard a loud crack or pop, you know what knuckle-popping sounds like. So, what would happen if you popped your knuckles all the time?
When you cut yourself accidentally, do you ever wonder what makes up this thing we call blood? It's pretty amazing stuff, considering how it wards off infections while supplying nutrients to every cell in the human body.
The heart is a vital organ that basically serves as a pump. Learn about heart chambers and valves, blood flow, the heart's electrical system and blood supply. Read more about how this amazing organ works.