A Quick Tour around your Brain

15 October 2013

Interview with 

Simon Bishop, Naked Scientist


How many brain cells does it contain? How heavy is it? How much fat? And how does it work? We take a quick fire science tour round your brain with Naked Scientist Simon Bishop.

Simon - Your brain weighs about 1.5 kg,

Hannah - That's about the same as a bag of sugar or your typical cauliflower -  it looks like one too.

Simon - Your brain makes up about 2% of your total body mass

Hannah - Even though it's not that heavy, it's a greedy hungry beast your brain, consuming about 20 % of your daily energy quota

Simon - What's using all this energy? There's almost 100 billion nerve cells up there.

Hannah - that's over 12 x the world population in terms of nerve cells in your head

Simon - These cells use electricity to send signals by pumping charged ions in and out of the cell. They then communicated with other cells by releasing neurotransmitter chemicals -- like dopamine and serotonin

Hannah - Each nerve cell is connected to between 1,000 to 10,000 other nerve cells, and it's through these connections that they send the signals through the brain network.

Simon - So, in total that's almost 1 × 10 to the 14 connections in your brain, or about 100 trillion.

Hannah - The human brain is the fattest organ in the body - over 60% of it is fat.

Simon - This fat wraps itself around the nerve cells and helps to insulate the electrical signal, making communication along nerve cells faster and stronger.

Hannah - Nerve signals can reach up to 120 metres per second, or 300 mph.

Simon - Contrary to popular belief, we don't use only 10% of our brains.

Hannah - It is true that we can only use a few specialised brain circuits at a time, but the rest of the brain is constantly ticking over, ready to be put to work.

Simon - You can find out more about how nerves work in our latest Science Scrapbook, at


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