Capacitance vessels have in their wall ?

Ans. is 'd' i.e., Less elastic tissue and less muscleVeins are capacitance vessels. They have less smooth muscle and less elastic tissue in their wall.Structure of vessels A) Structure of aeryIt is made up three layers -1.Tunica IntimaThe inner most layer (towards lumen) of aery is intima.It consists of endothelial cells which rest on basment membrane.There is some subendothelial connective tissue.Intima is separated from media by internal elastic lamina.2.Tunica MediaIt is mainly contains smooth muscles and laminae of elastic tissue Media is separated from adventitia by external elastic lamina.3.Tunica AdventitiaIt is the outer most layer.Contains collegen and elastic fibers.B) Structure of capillariesCapillaries are thin walled vessels made up of single layer of endothelial cells with its basement membrane. o Capillaries are of three types -1.Continous capillaries -These capillaries has continuous lining of endothelial cells with no fenestration.Basement membrane is also continuous.2.Fenesterated capillariesThere are fenestration between the endothelial cells.Basment membrane is continuous.3.Sinusoidal capillariesBoth endothelial cells and basement membrane have fenestration.In resting tissues, most of the capillaries are collapsed and blood flows through the throughfare vessels from the aerioles to the venules.C) Structure of veinsStructure of vein is smiliar to aery except that -1.Wall is thinner2.Three tunicae are less well demarcated.3.Elastic tissue is scanty and not clearly organized into distinct internal and external elastic lamina.4.Have valves (except venae cavae and common iliac vein).