Topic: oxygen

Stephen Porder explores how living organisms have transformed Earth through their use of hydrogen, oxygen, carbon, nitrogen and phosphorus. Drawing on his book Elemental, the conversation connects these biogeochemical changes across deep time with sustainability and choices that could reduce human environmental impacts.

Like all neural tissue, the retina has a high metabolic demand, and requires a constant supply of oxygen. Second and third order neurons are supplied by the retinal circulation, whose characteristics are similar to brain circulation. However, the photoreceptor region, which occupies half of the retinal thickness, is avascular, and relies on diffusion of oxygen from the choroidal circulation, whose properties are very different, as well as the retinal circulation. By fitting diffusion models to oxygen measurements made with oxygen microelectrodes, it is possible to understand the relative roles