Red blood cell synthesised by the kidney. Just before and after leaving the bone marrow, the developing cells are known as reticulocytes; these constitute about 1% of circulating red blood cells. The functional lifetime of a red blood cell is about 100–120 days, during which time the red blood cells are continually moved by the blood flow push (in arteries), pull (in veins) and a combination of the two as they squeeze through microvessels such as capillaries. They are also recycled in the bone marrow. The aging red blood cell undergoes changes in its plasma membrane, making it susceptible to selective recognition by
U2 Live at Red Rocks: Under a Blood Red Sky in October 1983 to promote U2's companion live mini-LP "Under a Blood Red Sky", which was released the following month. The mini-LP, whose name was later used as a subtitle for the concert film, features eight live songs from the War Tour, two of which ("Gloria" and "Party Girl") were taken from the Red Rocks concert; the other tracks were taken from performances in Boston and West Germany, as U2 thought they were "more developed performances". "U2 Live at Red Rocks: Under a Blood Red Sky" was U2's first home video release, initially released on VHS and Betamax by MCA