The very top of the wire drawing represents the only part of the ocean landscape that can be seen on the surface of the water: It is Bouvet Island, one of the most isolated islands in the world.

VOA: special.2009.05.06

The one that's on the top here is called ligand-gated ion channel and an ion channel is a protein that sits in the surface of a cell.

最上面的这个叫作配体门控离子通道,离子通道是一类位于细胞表面的蛋白

耶鲁公开课 - 生物医学工程探索课程节选