Nerve cells in the brain use vast amounts of energy, but can't store much fuel. Instead, fuel is transported to them along a vast web of blood vessels, which would stretch 400 miles long if spread out end to end. The web consists of large arteries (here white, in a mouse brain) that wind across the brain’s surface before penetrating into its depths and branching into smaller capillaries (red). These vessels constantly adapt to the changing energy demands of different brain regions. When a region is active, the nearby blood vessels will widen to allow extra blood and the fuel it carries to reach the area. However, scientists have not fully understood how the nerve cells and vessels communicate. Now research suggests that capillaries can detect the activity levels of cells. When they sense an increase, they send a signal that prompts upstream blood vessels to widen and increase blood flow.
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.