The Respiratory System
If you spread out the surface area of an adult human’s lungs, it would cover an entire tennis court.
The Nervous System
The nerves in your body can travel at speeds of up to 270 miles per hour.
The Digestive System
Despite its name, the small intestine is the longest part of the human digestive system, measuring around 20 feet—more than…
The Cardiovascular System
The cardiovascular system comprises the heart, arteries, veins, and capillaries...