Medical Research Council - London Institute of Medical Sciences

Now in our 8th year of bringing you beautiful imagery from biomedical science every day

Controlling Constriction
11 January 2013

Controlling Constriction

Our arteries and arterioles [small arteries] must keep blood flowing to the tissues at all times, ensuring a consistent oxygen supply. One way they achieve this is to control their diameters. Narrowing (vasoconstriction) or expanding (vasodilation) the vessels enables blood to flow more slowly or faster. To control constriction endothelial cells, which line the blood vessels, communicate with surrounding smooth muscle cells, telling them to either relax or tense up. The two cells types are separated by an elastic layer of cells (shown in white, with blue nuclei), but holes in the layer allow the endothelial cells to reach through with finger-like projections. Scientists now know that these projections contain particular proteins (yellow) that can detect the blood pressure inside the vessel, convey that information to the muscle cells, and ultimately keep blood flowing to where it’s needed.

Written by Ruth Williams

Search The Archive

Submit An Image

What is BPoD?

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.

Read More

BPoD is also available in Catalan at with translations by the University of Valencia.