What is endothelial function?

This is an excerpt from Advanced Cardiovascular Exercise Physiology-2nd Edition by Denise L. Smith & Bo Fernhall.

Properly functioning endothelium is critical to the health and function of the cardiovascular system. This section briefly describes the major functions of the endothelium. Specific functions are addressed in more depth ­later in this chapter and in subsequent chapters. As shown in figure 7.4, the vascular endothelium has multiple functions, and ­these functions are often specific to the site in the vascular tree. The primary functions of the endothelium include

1. serving as a selectively permeable barrier to regulate blood–­tissue exchange,
2. regulating vascular tone,
3. releasing anticlotting and proclotting ­factors to control hemostasis,
4. participating in inflammatory defense against pathogens, and
5. initiating new blood vessel formation (angiogenesis).