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Friday, March 1, 2013

Photoreceptors

Photoreceptors
Photoreceptors Photoreceptors are Light Receptors in Your Eye
Light enters the eye done the pupil. The amount of frolicsome that enters is

controlled by the muscles of the iris. Light rays are center by the lens onto the retina, which lines the inside of the eye. The retina contains photoreceptor cells these detect light. The fovea is an line of business of the retina where there are lots of photoreceptors. Nerve impulses from the photoreceptor cells are carried from the retina to the thinker by the heartal nerve, which is a bundle or neurones. Where the optic nerve leaves the eye is called the blind spot there arent any photoreceptor cells, so its not raw(a) to light. Photoreceptors commute Light into an Electrical Impulse
Light enters the eye, hits the photoreceptors and is absorbed by light



sensitive photo pigments. (Light goes straight through the neurones to the photoreceptors). Light bleaches the pigments, causing a chemical change and altering the membrane permeability to sodium. A generator potential is created and if it reaches the threshold, a nerve impulse is displace along a bipolar neurone. Bipolar neurones connect photoreceptors to the optic nerve, which takes impulses to the brain. The human eye has two types of photoreceptor rods and cones.

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Rods are mainly pitch in the peripheral parts of the retina, and cones are found jam-packed together in the fovea. Rods give information in dull and white (monochromatic vision), but cones give information in contort (trio chromatic vision). There are three types of

cones red-sensitive, green-sensitive and blue-sensitive. Theyre worked up in diverse proportions, so you can secure different colours. Rods are more sensitive but cones let you see more detail. Sensitivity · Rods are very sensitive to light (they fire action potentials in dim light.) This is because many rods relate one neurone, so many weak generator potentials intermix to reach the threshold and trigger an action...If you want to get a full essay, order it on our website: Ordercustompaper.com



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