97 relations: Action potential, Anterior chamber of eyeball, Anterior segment of eyeball, Aqueous humour, Astronomer, Astronomical object, Averted vision, Binocular vision, Bipolar neuron, Bird vision, Blind spot (vision), Blinking, Blood vessel, Cell membrane, Cellular respiration, CGMP-specific phosphodiesterase type 5, Chemical substance, Choroid, Ciliary body, Circadian rhythm, Collagen, Color space, Color vision, Cone cell, Conjunctiva, Connective tissue, Cornea, Corneal endothelium, Corneal limbus, Cyclic nucleotide–gated ion channel, Depth of field, Dichromacy, Edema, Electromagnetic radiation, Encyclopædia Britannica, Eye, Eyebrow, Eyelash, Eyelid, Fibrous tunic of eyeball, Fovea centralis, Fundus (eye), Hominidae, Hyperpolarization (biology), Immune system, Intrinsically photosensitive retinal ganglion cells, Iris (anatomy), Lens (anatomy), Light, Mammal, ..., Melanopsin, Melatonin, Microorganism, Mucus, Neurotransmitter, Nictitating membrane, Ophthalmology, Opsin, Optic disc, Optic nerve, Orbit (anatomy), Osmosis, Oxygen, Pathogenic bacteria, Photopsin, Photoreceptor cell, Photosensitivity, Pineal gland, Plural, Posterior chamber of eyeball, Posterior segment of eyeball, Primary color, Protein, Pupil, Reading (process), Red-eye effect, Reflex, Retina, Retinal, Retinal ganglion cell, Retinohypothalamic tract, Rhodopsin, Rod cell, Saline (medicine), Sclera, Suprachiasmatic nucleus, Synapse, Tapetum lucidum, Tears, Transducin, Trichromacy, Uvea, Visual cortex, Visual impairment, Vitreous body, Vitreous membrane, Wavelength. Expand index (47 more) » « Shrink index
In physiology, an action potential occurs when the membrane potential of a specific axon location rapidly rises and falls: this depolarisation then causes adjacent locations to similarly depolarise.
The anterior chamber (AC) is the fluid-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium.
The anterior segment or anterior cavity is the front third of the eye that includes the structures in front of the vitreous humour: the cornea, iris, ciliary body, and lens.
The aqueous humour is a transparent, watery fluid similar to plasma, but containing low protein concentrations.
An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside the scope of Earth.
An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.
Averted vision is a technique for viewing faint objects which uses peripheral vision.
In biology, binocular vision is a type of vision in which an animal having two eyes is able to perceive a single three-dimensional image of its surroundings.
A bipolar neuron or bipolar cell, is a type of neuron which has two extensions.
Vision is the most important sense for birds, since good eyesight is essential for safe flight, and this group has a number of adaptations which give visual acuity superior to that of other vertebrate groups; a pigeon has been described as "two eyes with wings".
A blind spot, scotoma, is an obscurity of the visual field.
Blinking is a bodily function; it is a semi-autonomic rapid closing of the eyelid.
The blood vessels are the part of the circulatory system, and microcirculation, that transports blood throughout the human body.
The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates the interior of all cells from the outside environment (the extracellular space).
Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products.
cGMP-specific phosphodiesterase type 5 is an enzyme from the phosphodiesterase class.
A chemical substance, also known as a pure substance, is a form of matter that consists of molecules of the same composition and structure.
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera.
The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor.
A circadian rhythm is any biological process that displays an endogenous, entrainable oscillation of about 24 hours.
Collagen is the main structural protein in the extracellular space in the various connective tissues in animal bodies.
A color space is a specific organization of colors.
Color vision is the ability of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect, emit, or transmit.
Cone cells, or cones, are one of three types of photoreceptor cells in the retina of mammalian eyes (e.g. the human eye).
The conjunctiva lines the inside of the eyelids and covers the sclera (the white of the eye).
Connective tissue (CT) is one of the four basic types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue.
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
The corneal endothelium is a single layer of cells on the inner surface of the cornea.
The corneal limbus is the border of the cornea and the sclera (the white of the eye).
Cyclic nucleotide–gated ion channels or CNG channels are ion channels that function in response to the binding of cyclic nucleotides.
In optics, particularly as it relates to film and photography, the optical phenomenon known as depth of field (DOF), is the distance about the Plane of Focus (POF) where objects appear acceptably sharp in an image.
Dichromacy (di meaning "two" and chroma meaning "color") is the state of having two types of functioning color receptors, called cone cells, in the eyes.
Edema, also spelled oedema or œdema, is an abnormal accumulation of fluid in the interstitium, located beneath the skin and in the cavities of the body, which can cause severe pain.
In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.
The Encyclopædia Britannica (Latin for "British Encyclopaedia"), published by Encyclopædia Britannica, Inc., is a general knowledge English-language encyclopaedia.
Eyes are organs of the visual system.
The eyebrow is an area of thick, delicate hairs above the eye that follows the shape of the lower margin of the brow ridges of some mammals.
An eyelash or simply lash is one of the hairs that grows at the edge of the eyelid.
An eyelid is a thin fold of skin that covers and protects the human eye.
The sclera and cornea form the fibrous tunic of the bulb of the eye; the sclera is opaque, and constitutes the posterior five-sixths of the tunic; the cornea is transparent, and forms the anterior sixth.
The fovea centralis is a small, central pit composed of closely packed cones in the eye.
The fundus of the eye is the interior surface of the eye opposite the lens and includes the retina, optic disc, macula, fovea, and posterior pole.
The Hominidae, whose members are known as great apes or hominids, are a taxonomic family of primates that includes eight extant species in four genera: Pongo, the Bornean, Sumatran and Tapanuli orangutan; Gorilla, the eastern and western gorilla; Pan, the common chimpanzee and the bonobo; and Homo, which includes modern humans and its extinct relatives (e.g., the Neanderthal), and ancestors, such as Homo erectus.
Hyperpolarization is a change in a cell's membrane potential that makes it more negative.
The immune system is a host defense system comprising many biological structures and processes within an organism that protects against disease.
Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye.
In humans and most mammals and birds, the iris (plural: irides or irises) is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina.
The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina.
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.
Mammals are the vertebrates within the class Mammalia (from Latin mamma "breast"), a clade of endothermic amniotes distinguished from reptiles (including birds) by the possession of a neocortex (a region of the brain), hair, three middle ear bones, and mammary glands.
Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene Opn4.
Melatonin, also known as N-acetyl-5-methoxy tryptamine, is a hormone that is produced by the pineal gland in animals and regulates sleep and wakefulness.
A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or in a colony of cells. The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from 6th century BC India and the 1st century BC book On Agriculture by Marcus Terentius Varro. Microbiology, the scientific study of microorganisms, began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera and anthrax. Microorganisms include all unicellular organisms and so are extremely diverse. Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms. These were previously grouped together in the two domain system as Prokaryotes, the other being the eukaryotes. The third domain Eukaryota includes all multicellular organisms and many unicellular protists and protozoans. Some protists are related to animals and some to green plants. Many of the multicellular organisms are microscopic, namely micro-animals, some fungi and some algae, but these are not discussed here. They live in almost every habitat from the poles to the equator, deserts, geysers, rocks and the deep sea. Some are adapted to extremes such as very hot or very cold conditions, others to high pressure and a few such as Deinococcus radiodurans to high radiation environments. Microorganisms also make up the microbiota found in and on all multicellular organisms. A December 2017 report stated that 3.45 billion year old Australian rocks once contained microorganisms, the earliest direct evidence of life on Earth. Microbes are important in human culture and health in many ways, serving to ferment foods, treat sewage, produce fuel, enzymes and other bioactive compounds. They are essential tools in biology as model organisms and have been put to use in biological warfare and bioterrorism. They are a vital component of fertile soils. In the human body microorganisms make up the human microbiota including the essential gut flora. They are the pathogens responsible for many infectious diseases and as such are the target of hygiene measures.
Mucus is a slippery aqueous secretion produced by, and covering, mucous membranes.
Neurotransmitters are endogenous chemicals that enable neurotransmission.
The nictitating membrane (from Latin nictare, to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus for protection and to moisten it while maintaining vision.
Ophthalmology is a branch of medicine and surgery (both methods are used) that deals with the anatomy, physiology and diseases of the eyeball and orbit.
Opsins are a group of proteins, made light-sensitive, via the chromophore retinal found in photoreceptor cells of the retina.
The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye.
The optic nerve, also known as cranial nerve II, is a paired nerve that transmits visual information from the retina to the brain.
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated.
Osmosis is the spontaneous net movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.
Oxygen is a chemical element with symbol O and atomic number 8.
Pathogenic bacteria are bacteria that can cause disease.
Photopsins (also known as Cone opsins) are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision.
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction.
Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light.
The pineal gland, also known as the conarium, kônarion or epiphysis cerebri, is a small endocrine gland in the vertebrate brain.
The plural (sometimes abbreviated), in many languages, is one of the values of the grammatical category of number.
The posterior chamber is a narrow space behind the peripheral part of the iris, and in front of the suspensory ligament of the lens and the ciliary processes.
The posterior segment or posterior cavity is the back two-thirds of the eye that includes the anterior hyaloid membrane and all of the optical structures behind it: the vitreous humor, retina, choroid, and optic nerve.
A set of primary colors is, most tangibly, a set of real colorants or colored lights that can be combined in varying amounts to produce a gamut of colors.
Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues.
The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina.
Reading is a complex "cognitive process" of decoding symbols in order to construct or derive meaning (reading comprehension).
The red-eye effect in photography is the common appearance of red pupils in color photographs of the eyes of humans and several other animals.
A reflex, or reflex action, is an involuntary and nearly instantaneous movement in response to a stimulus.
The retina is the innermost, light-sensitive "coat", or layer, of shell tissue of the eye of most vertebrates and some molluscs.
Retinal is also known as retinaldehyde.
A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye.
The retinohypothalamic tract (RHT) is a photic neural input pathway involved in the circadian rhythms of mammals.
Rhodopsin (also known as visual purple) is a light-sensitive receptor protein involved in visual phototransduction.
Rod cells are photoreceptor cells in the retina of the eye that can function in less intense light than the other type of visual photoreceptor, cone cells.
Saline, also known as saline solution, is a mixture of sodium chloride in water and has a number of uses in medicine.
The sclera, also known as the white of the eye, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some elastic fiber.
The suprachiasmatic nucleus or nuclei (SCN) is a tiny region of the brain in the hypothalamus, situated directly above the optic chiasm.
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target efferent cell.
The tapetum lucidum (Latin: "bright tapestry; coverlet", plural tapeta lucida) is a layer of tissue in the eye of many vertebrates.
Tearing, lacrimation, or lachrymation is the secretion of tears, which often serves to clean and lubricate the eyes in response to an irritation of the eyes.
Transducin (Gt) is a protein naturally expressed in vertebrate retina rods and cones and it is very important in vertebrate phototransduction.
Trichromacy or trichromatism is the possessing of three independent channels for conveying color information, derived from the three different types of cone cells in the eye.
The uvea (/ˈjuːvɪə/) (Lat. uva, grape), also called the uveal layer, uveal coat, uveal tract, vascular tunic or vascular layer is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when stripped intact from a cadaveric eye. Its use as a technical term in anatomy and ophthalmology is relatively modern.
The visual cortex of the brain is a part of the cerebral cortex that processes visual information.
Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses.
The vitreous body is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates.
The vitreous membrane (or hyaloid membrane or vitreous cortex) is a layer of collagen separating the vitreous humour from the rest of the eye.
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.