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theolduvaigorge:

This is how blue eyes get their colour

Blue eyes don’t get their colour from pigment – it’s actually way more fascinating than that.

  • by Fiona MacDonald

“Your eyes aren’t blue (or green) because they contain pigmented cells. As Paul Van Slembrouck writes for Medium, their colour is actually structural, and it involves some pretty interesting physics. As he explains, the coloured part of your eye is called the iris, and it’s made up of two layers – the epithelium at the back and the stroma at the front.

The epithelium is only two cells thick and contains black-brown pigments – the dark specks that some people have in their eye is, in fact, the epithelium peaking through. The stroma, in contrast, is made up of colourless collagen fibres. Sometimes the stroma contains a dark pigment called melanin, and sometimes it contains excess collagen deposits. And, fascinatingly, it’s these two factors that control your eye colour.

Brown eyes, for example, contain a high concentration of melanin in their stroma, which absorbs most of the light entering the eye regardless of collagen deposits, giving them their dark colour.

Green eyes don’t have much melanin in them, but they also have no collagen deposits. This means that while some of the light entering them is absorbed by the pigment, the particles in the stroma also scatter light as a result of something called the Tyndall effect, which creates a blue hue (it’s similar to Rayleigh scattering which makes the sky look blue). Combined with the brown melanin, this results in the eyes appearing green” (read more).

(Source: Science Alert)

Tags:

#eyes #biology #the power of science #neat

Image ~ ~ Brin ~ Leave a comment

northeastnature:

What do you do if you’re a harmless, gentle snake and someone scares the pants off you? If you’re an eastern hog-nose (Heterodon platirhinos), you bluff. And when you bluff, you bluff like crazy. You flare your neck like a cobra (spoiler alert: there are no cobras in the Northeast). If that fails, you roll over dramatically and play dead. If someone rights you, you make sure to roll back over so you look properly dead. You also release every bodily fluid you have on hand. Nearby humans may feel compelled to say “What a clever snake!” just because they can tell you’re really trying.

Tags:

#snake #anything that makes me laugh this much deserves a reblog #(‘you make sure to roll back over so you look *properly* dead’)

Image ~ ~ Brin ~ Leave a comment

astronomy-to-zoology:

Purple-throated Carib (Eulampis jugularis)

…a brilliant species of hummingbird (Trochilidae) which is known to breed on the islands of Antigua, Dominica, Guadeloupe, Martinique, Montserrat, Saba, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and Sint Eustatius. E. jugularis typically inhabit subtropical and tropical moist lowland forest and heavily degraded former forest.

Classification

Animalia-Chordata-Aves-Apodiformes-Trochilidae-Eulampis-E. jugularis

Image: Charlesjsharp

Tags:

#bird #pretty things

Image ~ ~ Brin ~ Leave a comment

skunkbear:

skunkbear:

Back when I was a studying biology, I noticed that a lot of anatomical terms sound like they come straight from Middle Earth. So, to celebrate the release of the last Hobbit film, I’ve created this INCREDIBLY nerdy quiz.

Do these words and phrases refer to parts of the human body, or reference people and places from J. R. R. Tolkien’s work?

  1. Antrum of Highmore
  2. Crypt of Morgagni
  3. Caves of Androth
  4. Lobelia
  5. Loop of Henle
  6. Scapha
  7. Great Vein of Galen
  8. Halls of Mandos
  9. Groin
  10. Gap of Calenardhon
  11. Macewen’s Triangle
  12. Canal of Schlemm
  13. Gerontius
  14. Islets of Langerhans
  15. Meckel’s Cave
  16. Chamber of Mazarbul

You shall not pass.

ANSWERS:

Anatomy – 1,2,5,6,7,11,12,14,15

Tolkien – 3,4,8,10,13,16

Both – 9!

  1. Antrum of Highmore – a big sinus next to your nose
  2. Crypts of Morgagni – small recesses on the surface of the urethra’s mucus membrane
  3. Caves of Androth – sheltered the Sindarin elves
  4. Lobelia – Lobelia Sackville-Baggins was Bilbo’s relative who wanted to own Bag End
  5. Loop of Henle – a long duct in the nephron of a kidney
  6. Scapha – the furrow in the upper part of your ear
  7. Great Vein of Galen – the vein that drains the brain
  8. Halls of Mandos – dwellings on the northern shores of Valinor
  9. Groin – in addition to being the junction between our legs, Groin was the father of Gloin and the grandfather of Gimli
  10. Gap of Calenardhon – AKA the Gap of Rohan, the land between the Misty Mountains and the White Mountains
  11. Macewen’s Triangle – part of your skull
  12. Canal of Schlemm – a channel that collects aqueous humor (that jelly in front or your iris) and delivers it to the blood stream
  13. Gerontius – AKA Old Took
  14. Islets of Langerhans – they produce hormones like insulin in the pancreas
  15. Meckel’s Cave – a little pouch of spinal fluid inside the skull.
  16. Chamber of Mazarbul – the room in Moria where Balin is enshrined, and where the Fellowship first fought the Moria orcs

Tags:

#Lord of the Rings #biology #now with detailed answer sheet #the more you know