Astrocytes: definition, appearance and general physiology 1

Published on April 28, 2022   35 min

A selection of talks on Cell Biology

0:00
Today I'm going to talk about neuroglial cells and about a specific subtype of neuroglial cells which are called astroglia or astrocytes. Now, by means of self-introduction, my name is Alexei Verkhratsky and I am a professor of Neurophysiology at the University of Manchester. All my life, I was studying glial cells in health and disease, trying to understand how the cells are working together with others in the brain, and what happens to them in conditions of pathology.
0:33
I'm going to talk about the brain. Of course, the human brain is something really outstanding and is probably the most complicated system which has ever been known to the natural sciences, because if you think about it, the evolution of it which lasted, probably, for about half a billion years, about 200 billion cells, 100 billion neurons and another 100 billion supportive cells, which we call neuroglia, and which is going to be the topic of my today presentation. On top of that, there are endothelial cells, pericytes, smooth muscle cells of blood vessels, all in the 1.5 litres volume of the skull. All of these cells are connected with, we don't know precisely, but certainly many 10s, if not 100s of trillions of connections. All this operates at a cost of 300-400 calories per day, which gives you about 12 watts an hour. As a computing machine, the brain has an operational memory in the range of more than 2.5 petabytes and operates at a petaFLOP range. Now, just for comparison, one of the world's fastest supercomputers, in Guangzhou, has a maximum processing speed of 33 petaFLOPS, a memory of 1.3 petabytes and does it all at the support of 17.6 megawatts of power. Now, on top of this, this particular computer occupies a huge space, its surface area is 720 m^2. In a sense, our brain is very much stronger and more powerful than any supercomputer in the world. It will probably remain so for a long time to come. Now, of course, the brain is really complex, and here I do very much love this quotation from Desiderius Erasmus, who said that, "All things in life are so multifaceted, contradictory and obscure that we can never be sure about the truth." That very much applies to the brain, because our knowledge is in a constant flux. What we know today probably contradicts with what we knew yesterday, and it will be contradicted again by what we will know tomorrow.
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Astrocytes: definition, appearance and general physiology 1

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