3.3 Blood Vessels

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TASK 3.1
Write a report comparing and contrasting the structure and function of the three types of blood vessels.
The Structure and Functions of Blood Vessels
ARTERIES
The walls of arteries contain smooth muscle fibre that contract and relax under the instructions of the sympathetic nervous system. The functions of the arteries are: transport blood away from the heart and transport oxygenated blood only. Arteries have four different parts, which are; lumen, endothelium, smooth muscle and connective tissue.
LUMEN=the lumen of arteries is relatively narrow to maintain high blood pressure.
ENDOTHELIUM=forms the inner layer of an artery wall, also known as the tunica interna. It consists mainly of endothelial cells.
SMOOTH MUSCLE= smooth muscle and elastic tissues
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Veins transport blood to the heart and lungs at low pressure after receiving it from the capillaries. Valves inside the veins keep blood moving in one direction.
The human body's arterial system branches out from one main artery, the dorsal aorta. Like veins, arteries have three layers: an outer layer of tissue, an inner layer of epithelial cells and a layer of muscle in between. Arteries deliver oxygenated blood to the capillaries, where the exchange of oxygen and carbon dioxide takes place. An artery's muscle helps it expand and contract in rhythm with the heart beating to keep blood moving through the system.
Capillaries connect veins and arteries to exchange oxygen and carbon dioxide. Thin and weak, capillaries are only as thick as one epithelial cell. Blood passes through capillaries one cell at a time, single file. The blood cells release oxygen, which passes through the capillary walls into nearby tissue. Tissue then releases carbon dioxide through the capillary walls into the red blood

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