Cardio Vascular System

Cardio Vascular System 

Blood Vessels 

There are three types of blood vessels in the body: arteries, capillaries, and veins. These are fundamental for the circulatory system. Arteries are the largest blood vessel, that are composed of a thick outer layer (tunica adventitia) made of connective tissue and smooth muscle and endothelium tissue in the inner layers (tunica media, tunica intima). The thickness of the arteries supports it's purpose, which is to deliver highly pressurized oxygenated blood from the heart to tissues in the body. Veins are have also three layers.  The main difference is the veins, the endothelium wall is thinner, this is because the pressure from the heart has less blood  pressure. The veins in their structure have valves to help grasp blood as it made be fighting gravity and so it helps to continue moving blood to the heart. The skeletal muscle in the inner layer ( tunica media) helps the blood moving by contraction. Capillaries are the smallest blood vessels. Capillaries connect arteries with veins. This smallest vessels web together to exchange oxygen, nutrients, and waste for all body cells. Capillaries can be really small that even blood cells can move single file through them. The volume of blood is distributed through this blood vessels: 30% of blood is found in the arteries, 5% of blood in the capillaries, and 65 % of blood in the veins.