Capillaries are very tiny blood vessels — so small that a single red blood cell can barely fit through them. They help to connect your arteries and veins in addition to facilitating the exchange of ...

The kidneys contain millions of microscopic blood vessels known as peritubular capillaries. These vessels recapture helpful nutrients like glucose and minerals and return them to your bloodstream for ...

The respiratory system allows air to reach the lungs, from which oxygen enters the blood and circulates to all body cells. This system also removes waste gases from the body and helps prevent disease ...

The respiratory system is responsible for the exchange of carbon dioxide and oxygen in the human body. This system also helps remove metabolic waste products and keep pH levels in check. The major ...