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In the alveoli, oxygen from the air is absorbed into the blood. Carbon dioxide, a waste product of metabolism, travels from the blood to the alveoli, where it can be exhaled. Between the alveoli is a thin layer of cells called the interstitium, which contains blood vessels and cells that help support the alveoli.
Its called tunica intima The tunica media is the middle layer in a blood vessel wall and is composed predominantly of smooth muscle reinforced by organised layers of elastic tissue which form elastic laminae.onfidence votes 2. The three layers of the arterial wall are, from outside to inside, the adventia, the media and the intima. A flat layer of cells, called endothelial cells, forms a boundary between the blood in the lumen, or cavity, and the innermost layer of the arterial wall.