The endothelium is a cell layer that lines the body’s blood vessels and lymphatic vessels. These cells are necessary to maintain healthy organs, tissues, and overall body function. The cells of the ...

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 ...

Plasma makes up about 55 percent of your blood. It carries out several key functions in the body, including transporting waste products. Read on to learn more about plasma, including what it’s made of ...

Blood is made up of plasma and solid components. Of these, the larger part is plasma, comprising about 55%. It appears as a straw-colored fluid and is composed mainly of water, but also carries ...

Red blood cells are important mediators of the innate immune system. Depending on the cellular environment, these cells either activate the immune system or maintain the system in a dormant state. In ...