Featuring blushing, yawning, hiccups, and blue skies.
Why do we sweat when we're nervous?
Your body deals with a potential threat by going into fight-or-flight mode. This involves the part of your brain that controls basic functions, the hypothalamus, telling your adrenal gland to release a ton of hormones. One of these is epinephrine, also known as adrenaline, and is what gets your sweat glands going. The idea is that you'll need to keep cool while you're confronting the threat — even if it's just giving a presentation.
Via etudianteendesign.tumblr.com
Why do we blush?
This is another symptom of the fight-or-flight response. When you're embarrassed, your body releases adrenaline. Your blood vessels then dilate in order to get more oxygen to your muscles by letting more blood through your veins. This has the unfortunate side effect of making your face look redder. Oh, and it's an involuntary reaction, so there's absolutely nothing you can do about it.
Via canyoureleaseme.tumblr.com
Why is the sky blue?
Sunlight looks white, but it's actually made up of all the colours in the rainbow. When it hits Earth's atmosphere it is scattered by particles in the air. Different colours of light have different wavelengths, and blue is the shortest, so it gets scattered most. That's why the sky looks blue.
Why do we yawn?
You probably know that yawning is contagious. Seeing someone else yawn, or even just reading this sentence, might trigger you to yawn yourself. There are several theories about why we yawn in the first place but the latest — that we yawn to cool down our brains — seems to be sticking.
Via giphy.com