What is the function of the tunica interna?

Question

Quizplus · Accepted Answer

Tunica externa is the outermost layer of the vessel wall. It is composed of loose connective tissue, which serves to anchor the vessel to surrounding tissue, and provide passage for nerves and small vessels supplying blood to the external wall. Tunica media is the middle layer of the vessel wall. It is the thickest layer, composed mostly of smooth muscle. This tunic is more muscular in arteries than veins of comparable size. Tunica interna is the lining of the vessel wall. It is composed of endothelium (simple squamous epithelial tissue and fibrous tissue). It is vital that this layer is very smooth and secretes a chemical to repel platelets so blood can easily flow through the vessel.

What Is the Function of the Tunica Interna