Circulatory System
Is a transport system that carries blood and lymph to and from the tissue of the body.
Blood vessels :
Blood vessels are arranged so that blood delivered from the heart quickly by arteries reaches a network of narrow thin walled vessels, the blood capillaries.
General features of Arteries &Veins :
They are composed three layers called tunics they are from the lumen outward :
1-Tunica intima : The innermost layer that includes the endothelial lining (a single layer of simple squamous epithelial tissue ),resting on a basal lamina and the underlying connective tissue .
2-Tunica media : The muscular middle layer (consists primarily of circumferentially arranged layers of smooth muscle cells ).
3- Tunica adventitia : The outermost connective tissue layer.