What's Happening When You Suck in Air?

Okay this is a rather strange sounding title. It alludes to the actual process of breathing in and of blowing out, and to the actual mechanisms behind this.

The human body is a remarkable thing, and while we might think that we understand a lot of it, there are actual many very ‘every day’ processes that we know little about. For instance sucking in – you do it completely naturally, but how can we affect the air particles that are nowhere near us? What is the process that this actually works through? If you have a little bit of a background in science or engineering then you can skip past this one, but for anyone else who isn’t already familiar with the process this might shed light on something we often take for granted.

Pressure

Both our breathing in and our breathing out are reliant on pressure and the way it works. Put simply it relies on pneumatic energy in just the same way as a pneumatic drill, which gains its power from tightly packed air particles in a small space.

Pressure is determined by the number of particles in a given space. When you measure the PSI in your car tires this is to tell you how many air or nitric oxide particles there are in the tire. The more tightly packed the more they will push out on the outside of the tire and provide a firm base for the car. The reason that these particles push outward meanwhile is that they will always try to space themselves out evenly across the available space. In other words, if you blow some air into a box it won’t simply sit in the corner as a ‘lump’ but rather it will spread to evenly fill the entire box. The same happens when you drip water onto a plate – it will spread outwards to evenly cover the plate rather than piling up on the top.

Then, if you were to pop that tire the air would come gushing out in order to fill the area outside. This is because the pressure in the tire again wants to spread out in the available space – now the entire atmosphere – and that causes it to rush in all directions. This is called ‘equalization’ and it’s also why our eyeballs would be sucked out of our skulls if we went into space without a space suit, and why a breach in the hull of an airplane causes everything to get sucked out into the void. Again you can make a comparison to water and in this case it’s like a dam – as soon as the tire bursts it would be like the dam collapsing and all the water rushing outward.

How We Suck

When we suck then we use these principles to our advantage by simply using our muscles to expand the cavity in our mouth and lungs, and then opening our mouth to allow the particles to rush in. What you have done then is to create an area of low pressure in your body by increasing the space in your lungs and mouth without increasing the number of particles to keep the ratio constant. This then causes the particles from outside which are in a higher pressure area to ‘rush’ into your mouth and lungs to equalize the pressure. You can also then use this to drag very small and light objects – just like breaking the hull of the plane. Put a small piece of paper on the table and suck hard to pull it across to you. In this scenario the paper is in the plane and you are the atmosphere outside. This is also the exact same way that a vacuum cleaner works.

You can also then use this sucking ability of course to drink water, for as we noted the same laws of pressure apply to water, and you can use it to make ‘hickies’ on your skin because the blood in your veins is ‘rushing’ up to the surface of your skin in an attempt to fill the void in your mouth. Pretty disgusting…

Blowing

Of course blowing out is the exact opposite process. Here you use the muscles in your mouth and lungs in order to create and area of high pressure by simply shrinking the available space. Now your mouth is the airplane and all the particles will rush out through the small hole you create. The smaller the hole, the more pressure will be in the small stream coming out.

What’s incredibly is that most of us do all this without knowing anything about pressure. Cats and dogs do it to, and we whistle and talk using these principles too. Just as when we catch a ball we are actually doing incredibly advanced mathematics to predict the trajectory of the ball and put our hand in the right place in order to stop it. The human body really is an incredible thing…

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