The blood in the vessels normally does not clot because of the following:
High-Yield Explanation
Blood in the vessels do not clot because of two reasons : 1. Endothelial membrane is coated by highly charged polysaccharide called glycocalyx. Due to its high density glycocalyx contribute to the non thrombogenic propeies of surface of intact epithelium. 2. The luminal surface of the endothelium is smooth.