There are three types of blood vessel, Arteries , veins and capillaries. Each of them have different functions involved in carrying blood around the body . Arteries are blood vessels that transport blood away from the heart, veins are blood vessels that transport blood to the heart and Capillaries are extremely small vessels located within the tissues of the body that transport blood from the arteries to the veins. they must be constructed for carrying fluids over long distances, allowing for exchange of materials to and from the blood, and for vasoconstriction/vasodilation to alter blood flow. The walls of the blood vessels allow for all these things
Capillaries are the smallest of a body's blood vessels. ‘It’s just a single layer of simple squamous epithelial cells surrounded by a basement membrane’(URL1) this is where there is the delivery of nutrients and oxygen as well as the and removal of waste products and carbon dioxide .
The above images shows the most common blood capillaries that are seen in the skin and on the muscles. Blood flows away from the heart to arteries which follow into arterioles, and then narrow further into capillaries. then capillaries branch and widen to become venules and then widen more and connect to become veins therefore returning the blood to the heart. The exchange of carbon dioxide and Oxygen takes place in the cell walls. Capillaries have the function is to supply tissues with blood, and also to remove waste from the surrounding cells ... as opposed to simply moving the blood around the body as seen with the other types of blood vessel. (URL2)’ The flow of blood in the capillaries is controlled by structures called precapillary sphincters’(URL3). These structures are located between arterioles and capillaries and contain muscle fibres that allow them to contract.
A vein is an blood vessel that...