The Function Of The Cone

Most individuals take for granted their ability to see. Eyesight is a major connection to the outside world; around 80 percent of impressions are through sight, meaning that only 20 percent are from the other four senses. The human eye has evolved over time to turn into what it is today. Through human’s needs for survival, the eye has changed to suit humans. Two of the most common types of eyes found in nature are the camera-type eye and compound eyes; the human eye fits into camera-type eyes because just like a camera lens focuses light onto something, the eye does a similar thing. The cornea, a structure in the front of the eye, focuses light onto the retina, and behind the cornea, is a colored membrane called the iris. It has an adjustable circular opening, the pupil, which expands or contracts to determine the amount of light that enters the eye.

 A.accommodation B.the concentration of cones in the fovea C.chemical structure of the vitreous humor D.the prevalence of amacrine cells in the

The retina is what houses the eye’s rods and cones. The eye has about 6 million cones and 120 million rods. Both rods and cones get their names from their shape. Rods do not provide color vision, and are sensitive to dim light. Cones function well in the day and provide color vision.

What are rods and cones? Where are they found? What is the macula? What is the optic disk?

To understand the diverse causes of RP, a basic understanding of visual perception is required. Phototransduction (conversion of light to electrical signals) occurs first, which is initiated by two types of photoreceptors: rods and cones. These two types vary in their function as rods are primarily responsible for night vision and lack sensitivity to color while cones function in color vision. Light contacts these photoreceptors, and isomerizes a retinaldehydechromophore (retinal) which is bound to varying types of opsin proteins corresponding in their reactivity to different wavelengths of light. Upon absorption of a photon of light, the chromophore 11-cis-retinal is isomerized to the all-trans confirmation, which subsequently causes a series of molecular interactions which ultimately result in the electrical response of the photoreceptors (Vugler 2010). As 11-cis-retinal is required to absorb photons of light, this compound must be regenerated, a function that is performed with the aid of nearby cells of the retinal pigment epithelium

Color Vision Development in Infants: The Responsibility of Cone Types and Wavelength in Order of Color Development

Tapeta can be classified according to their location in vertebrates and mechanism in invertebrates. Choroidal tapeta are the most common and are classified as tapetum fibrosum and tapetum cellulosum. The simplest type is the tapetum fibrosum, which is found principally in mammals, including herbivores (elephants, horses and goats), cetaceans (whales and dolphins), certain marsupials (Tasmanian Devil), and a rodent (Cuniculus pacas). The tapetum fibrosum consists of extracellular collagen fibrils that are stacked orderly with the majority of the its fibers running horizontally. The number of layered fibrils varies between species and can be up to several hundred thick. The most studied tapetum fibrosum among mammals is found in the cow and is located posteriorly and dorsally. The thickness is variable, increasing its thickness posteriorly. In species with a choroidal tapetum, the retinal epithelium in the area is the tapetum in un-pigmented, it allowing the light to pass subsequently reflected by the tapetum. This contrasts with the pigmented retinal epithelium

The eyeball holds many parts to allow eyesight. The retina holds the key to allowing the human eye to see color. The pupil appears as the black part of the eye that people see, the pupil however does not have much to do with comprehending color. As Clarence Rainwater said in his book “The pupil is simply the hole in the iris through which light enters the eye.” (84) The light then has to pass through many parts of the eye before reaching the retina such as the transparent cornea, the aqueous humor, the lens, and the vitreous humor. Clarence Rainwater described the retina as “... the eye’s sensitive inner surface.” (86) The exciting part of the eye starts here. The retina holds the key as stated by Clarence Rainwater, “... a complex system

Secondly, pigment cells do not differentiate due to obvious deficiency in rhodopsin-expressing rod photoreceptor cells. Finally, the cornea, iris, and ciliary body do not develop, although neural crest cells migrate to the eye region like in surface fish, and sclera, although present, remains cartilaginous instead of ossified. The author went into very great detail describing the processes of development of the fish eye, but I had an extremely hard time following along with what he was saying because it was very difficult to picture all of the structures he was describing. I gained quite a bit of understanding from the pictures and figures provided, but I really would have appreciated more detailed diagrams that pointed out the specific structures discussed. This section gave me a much larger appreciation for the complexity of the eye, and its overall point was to prove that cavefish eye develops normally for a considerable amount of time before finally disappearing due to failure to keep up with overall body growth. These finding do not support the hypothesis that proposes loss of function of genes involved in early eye development. It also discounts the hypothesis that the embryonic eye was eradicated in order to conserve

The development of the human body is an exquisite process that involves numerous complicated processes for even the smallest of body parts, including the eyes. The eyes are an extraordinarily complex organ capable of gathering information through refracted light and sending it the brain to assemble a picture. They provide the ability to see and follow a moving object and the capability to tell an approximate distance of an object. When light passes through the cornea and iris pupil, at the anterior portion of the eye, it is focused by the lens onto the retina at the back of the eye. Photoreceptor cells, which are present in the retina, detect the light and send information to interneurons which begin to sort out the information. This information is then sent to ganglion cells which transmits the final information to the brain (Sowden 199). Because the eyes have such complicated and exquisite processes, the likelihood of developmental errors occurring are possible. A large number of these developmental errors lead to congenital defects and abnormalities that effect the individual’s eye sight. Some of these defects and abnormalities can cause serious diseases and syndromes that effect more than just the eyes, but also neurological processes, facial dimorphisms, growth failure, tracheal development, and genitalia anomalies.

Cone cells are used for color vision while rods are used to see in black and white. The cone cells can pick up 3 basic colors; red, green, and blue. When they pick up light, photosensitive chemicals in the outer part of a cell release a electrical charge, allowing the brain to precieve the light as color. They use different groupings of these colors

Our eyes have different parts or layers you can call it. On the very top layer, there is the lens, which just like a camera help us focus on certain images. Then there is the eyeball which helps us see and also this is the only area of the eye that is pigmented. Behind the eyeball is the retina, this layer deals with sensitivity to light and triggers nerve impulses. The retina itself has a layer that basically consists of two light-sensitive cells.

Humans have three cone cells that are extremely sensitive to Red, (620-700nm), Green (490-570nm) and Blue (450-495nm) wavelengths of light. Although these three cones are most sensitive to these wavelengths, they are still sensitive to the remaining wavelengths of visible light between 400-700nm. When a light with a wavelength of 600nm is transmitted through the retina, the Red and Green cones capture, sense and signal the brain that orange light is observed. In this case the Red and Green cones absorb light but the Green cones are less sensitive. Also, the Blue cones don’t absorb much light and are not sensitive

The optic nerve reaches from behind the eyes to the occipital lobe where this visual information can finally be interpreted into what we know as ‘seeing something’. It is at this point that it is useful as this is when colours can be perceived (Breedlove, 2010).