First 490 words of the document:
Vein Artery Capillary
Wall thickness 1.0 m the blood is at a low pressure so the walls do not have to 1.0 mm is thick so can withstand the high pressure at which the 8.0 m very thin walls which allows diffusion of materials to
be thick blood is. be much quicker
Lumen Relatively large to ease the flow of blood Is relatively small to maintain high pressure Is very narrow with the diameter being of that of a red blood
cell (7 m). This allows the red blood cells to squeeze as
they pass thought the capillaries helping them give up their
oxygen due to the closeness to the capillary wall so the
diffusion path is reduced.
Elastic Tissue Does contain thinner layers of elastic tissue to veins. However not Contains elastic tissue and allows the wall to stretch and recoil Does not contain elastic tissue.
needed as veins do not contract or recoil and are not actively when the heart is pumped. This is felt as a pulse in areas where
constricted to reduce blood flow. the artery is close to the skin. The recoil helps to maintain the
Smooth Does contain thinner layers of smooth muscle but not needed as Has smooth muscle that can contract and constrict the artery. This Does not contain smooth muscle
Muscle veins do not contract or recoil and are not actively constricted to constriction narrows the lumen of the artery. (In arterioles like
reduce blood flow. smaller arteries the smooth muscle is used to limit the blood flow
to certain organs/tissues so it can be directed to other tissues)
Collagen Does contain thinner layer of collagen but not necessarily Collagen is located in the wall to give it strength to help withstand Does not contain collagen
Fibres needed as blood vessel does not transport high pressures of blood. high pressures of the blood.
Endothelium Has an endothelium layer of cells Endothelium can be folded and unfolded when the artery The walls are just a single layer of endothelium cells this
(single layer of stretches helps to reduce the diffusion distance for the materials being
Valves Veins have valves which help the blood flow back to the heart No valves No valves
and to prevent it flowing in the opposite direction. As the walls
are thin the vein can be flattened by the action of surrounding
skeletal muscle. Pressure is applied to the blood, forcing the
blood to move along in the direction dictated to by the valves.
Transports Transport deoxygenated blood apart from the pulmonary vein Transports oxygenated blood apart from the pulmonary artery Deoxygenated blood and oxygenated blood.
which transports oxygenated blood from the lungs to the heart. which transports deoxygenated blood from the heart to lungs.