- published: 05 Jul 2016
- views: 21562
Eye color or eye colour is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris.
In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. The appearance of blue and green, as well as hazel eyes, results from the Tyndall scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering. Neither blue nor green pigments are ever present in the human iris or ocular fluid. Eye color is thus an instance of structural color and varies depending on the lighting conditions, especially for lighter-colored eyes.
The brightly colored eyes of many bird species result from the presence of other pigments, such as pteridines, purines, and carotenoids. Humans and other animals have many phenotypic variations in eye color. The genetics of eye color are complicated, and color is determined by multiple genes. So far, as many as 15 genes have been associated with eye color inheritance. Some of the eye-color genes include OCA2 and HERC2. The earlier belief that blue eye color is a simple recessive trait has been shown to be incorrect. The genetics of eye color are so complex that almost any parent-child combination of eye colors can occur. However, OCA2 gene polymorphism, close to proximal 5′ regulatory region, explains most human eye-color variation.
Eyes are the organs of vision. They detect light and convert it into electro-chemical impulses in neurons. In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.
The simplest "eyes", such as those in microorganisms, do nothing but detect whether the surroundings are light or dark, which is sufficient for the entrainment of circadian rhythms. From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment and to the pretectal area to control the pupillary light reflex.
Color (American English) or colour (Commonwealth English) is the visual perceptual property corresponding in humans to the categories called red, blue, yellow, etc. Color derives from the spectrum of light (distribution of light power versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical specifications of color are also associated with objects or materials based on their physical properties such as light absorption, reflection, or emission spectra. By defining a color space colors can be identified numerically by their coordinates.
Because perception of color stems from the varying spectral sensitivity of different types of cone cells in the retina to different parts of the spectrum, colors may be defined and quantified by the degree to which they stimulate these cells. These physical or physiological quantifications of color, however, do not fully explain the psychophysical perception of color appearance.
The science of color is sometimes called chromatics, colorimetry, or simply color science. It includes the perception of color by the human eye and brain, the origin of color in materials, color theory in art, and the physics of electromagnetic radiation in the visible range (that is, what we commonly refer to simply as light).
"Preparing yourself to be honest
Will it happen in your grave?”.
Laugh at your cancerous ways
With no means of repression, what the fuck can you do
but live?
Discover that life has meaning when you let that
meaning go
Put a mic to those idiots in your head
Let the posers around you laugh as they listen to
themselves
Fuck the disabled body of your fears, see it is not
yours
Give it back to whom it belongs, to no one [2x]
Creativity or fear
The choice is yours
The dangerous dignity of man
Embrace it or be consumed
By imported dreams
Investing your life in distraction
It creates fear being away from home
Around that fear you built your life
Feeling alive can happen this moment, needs no
preparation
Preparing yourself to be honest, will it happen in your
grave?
Fuck the disabled body of your fears, see it is not
yours
Give it back to whom it belongs, to no one [2x]
Put a mic to those idiots in your head
Let the posers around you laugh as they listen to
themselves
Preparing yourself to live tomorrow, you might not get
another chance
Urgency enables
The possible dignity of man
The threatening dignity of man
It shall threaten you until you love yourself
Creativity or fear, the choice is yours,
The dangerous dignity of man
Embrace it or be consumed
By imported dreams
Rip through the falsehood inhabiting the body you call
yourself
Fuck those intruders so deeply they will never return
to your home
Then fuck yourself so deeply you will never return
Then let life inhabit your body
You believe something new will emerge
Reverence for the remote controlled life
Preprogrammed options, a timeframe so limited,
Nothing substantial
Fuck your drama, seeking acceptance and a fair judgment
You cannot accept yourself!
Forget all judgments and embrace what is in your
control; your choice
Fear or creativity
Fuck the disabled body of your fears, see it is not
yours
Give it back to whom it belongs, to no one [2x]
You believe something new will emerge
Reverence for the remote controlled life
Preprogrammed options, a timeframe so limited