IF OUR BLOOD IS RED, WHY ARE OUR VEINS BLUE?

Why do veins look blue? One answer you're likely to hear is that veins look blue because the blood inside actually is blue, because it's deoxygenated. If you wonder why you've never seen blue blood before, someone might tell you that's because when you bleed, the blood is oxygenated upon contact with air, and immediately turns red.

First things first: Our blood is not blue. It is always red. 1Even when it's deoxygenated. Even in the absence of oxygen in a vacuum. (Remember, when you get blood drawn at your doctor's office, they use a vacutainer, which is essentially a vacuum in a tube. The tube is attached to the needle in your arm, exposing the inside of the vein to the vacuum and drawing the blood out.)

How red it is varies.

After your blood is pumped to your lungs by your heart, it's bright red because hemoglobin -- the iron-containing, oxygen-transporting protein in our red blood cells -- binds to the oxygen the blood just picked up. From the lungs, the blood goes back to the heart (this is called pulmonary circulation), which pumps it out to the rest of the body via the arteries and into tiny blood vessels called capillaries, where it gives its oxygen to the body's tissues (systemic circulation). On its return trip to the heart through the veins, the oxygen-depleted blood is dark red or maroon, because the hemoglobin is no longer bound to oxygen.

WHY SO BLUE?

Now, I'm no surgeon, but real doctors will tell you that when you poke around inside a human being and see a vein or artery in its naked glory, it isn't blue. If blood isn't blue, and veins and arteries aren't actually blue, why do our veins look blue through our skin?

When you look down at the veins in your arm, light of different wavelengths is hitting the skin, the veins and the blood. Some of that light is being absorbed, and some is getting scattered and reflected back to your eye. Different wavelengths of light have different properties and abilities. As it turns out, blue light, compared to red light 1) doesn't penetrate the skin as well, 2) is absorbed by the blood more, and 3) is more likely to be scattered and make it back to your eye.

So, if a vein is close to the surface of the skin, most of the blue light will be absorbed, and even though red light doesn't reflect as much, the red light:blue light ratio is high enough to make the vein appear red. With deeper veins, the blood doesn't absorb as much blue or red light. But the blue light's inability to penetrate as deeply as red light makes the veins appear blue.

1 Note the "our" in that statement. Humans and all other animals with backbones have red blood, but some animals, such as lobsters, crabs, crawfish, octopodes, squid, mussels and clams, do have blue blood.

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WHY DO PAPER CUTS HURT SO MUCH

As far as injuries go, paper cuts look pretty harmless, but there’s no denying the fact that they can feel disproportionately agonising.

And when you look at what's going on at a scientific level, paper cuts are surprisingly brutal, as Ferris Jabr explains in the episode of Scientific American’s Instant Egghead below.

For starters, the fact that we’re most likely to experience paper cuts on our nerve-coated fingertips makes the potential for pain pretty high from the start. 

Our fingers are covered with plenty of neurons, including nociceptors, which are there to detect any potential harm, such as from harsh chemicals, high temperatures and also pressure that might break the skin, as Jabr explains.

Any of these feelings will trigger electrical and chemical signals that make the brain painfully aware of an injury, and this tell us to stop doing whatever it is we’re doing.

But a paper cut doesn’t just cause the pain of a regular cut. Although it may look like a pretty clean incision, if you look at paper under a microscope it’s actually a nightmarishly jagged surface that rips apart our cells and nerve endings.

“The piece of paper cuts through skin more like a small saw than a knife,” Jabr explains. “As if that wasn’t horrible enough, paper leaves behind chemical particles, irritating the wound."

Because paper cuts are so shallow, they actually don’t bleed or clot very much, which leaves all your tissue and nerves exposed. Ouch.

Plus, there’s also the psychological pain, which comes from knowing that we can be injured so badly by something as small and innocuous as paper. We made you paper, why do you have to be so mean?





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ENGLISH 101: WHEN TO DOUBLE CONSONANT

Is it dialled or dialed?

When adding -ing and -ed to verbs, we sometimes double the consonant beforehand. People are often confused with ‘dialled/dialed’, ‘benefitted/benefited’, ‘focussed/focused’ and ‘targetted/targeted’. This tip answers some of those queries.

The official requirements are that we ‘double a single consonant letter at the end of any base where the preceding vowel is spelled with a single letter and stressed’.

What does this mean in practice?

Examples:

word	present participle	past participle
bar	barring	barred
beg	begging	begged
occur	occurring	occurred
permit	permitting	permitted
patrol	patrolling	patrolled

It is true to say that there is usually no doubling when the preceding vowel is unstressed (‘enter’ becomes ‘entering/entered’; ‘visit’ becomes ‘visiting/visited’) or when the preceding vowel is written with two letters (‘tread’ becomes ‘treading/treaded’).

Dial

With ‘dial’, even though the preceding vowel is written with two letters (so you would think that there would be no doubling), it becomes ‘dialling/dialled’ (though not in American English, as mentioned).

Some words change their spelling to cope (they add a letter ‘k’).

word	present participle	past participle
panic	panicking	panicked
traffic	trafficking	trafficked
frolic	frolicking	frolicked
bivouac	bivouacking	bivouacked

What about ‘focus’?

This word can take either double or single s, with the single option being highly preferred.

word	present participle	past participle
focus	focusing/focussing	focused/focussed

Here’s an odd one to end:

American	British English
parallel	parallel
paralleling	parallelling
paralleled	parallelled

Example:

The vetting service from Future Perfect is unparallelled.