Red blood cell being dissolved in body fluid) was an important step in the evolution of vertebrates as it allows for less viscous blood, higher concentrations of oxygen, and better diffusion of oxygen from the blood to the tissues. The size of red blood cells varies widely among vertebrate species; red blood cell width is on average about 25% larger than capillary diameter, and it has been hypothesized that this improves the oxygen transfer from red blood cells to tissues. The red blood cells of mammals are typically shaped as biconcave disks: flattened and depressed in the center, with a dumbbell-shaped cross section,
Under a Blood Red Sky Under a Blood Red Sky Under a Blood Red Sky is a live album by Irish rock band U2, produced by Jimmy Iovine and released on 21 November 1983. Along with its companion concert film, "", the release helped establish U2's reputation globally as a live act. The album consists of live recordings from three shows on the band's War Tour, from Colorado and Boston in the US and from Germany. An accompanying concert video entitled "U2 Live at Red Rocks: Under a Blood Red Sky" was released the following year. The film was recorded entirely at the outdoor Red