Editing Sensory neuron (section)

==== Vision ====
[[Photoreceptor cell]]s are capable of [[phototransduction]], a process which converts light ([[electromagnetic radiation]]) into electrical signals. These signals are refined and controlled by the interactions with other types of neurons in the retina. The five basic classes of neurons within the retina are [[photoreceptor cell]]s, [[bipolar cells]], [[Retinal ganglion cell|ganglion cells]], [[horizontal cells]], and [[amacrine cells]]. The basic circuitry of the retina incorporates a three-neuron chain consisting of the photoreceptor (either a [[Rod cell|rod]] or [[Cone cell|cone]]), bipolar cell, and the ganglion cell. The first action potential occurs in the retinal ganglion cell. This pathway is the most direct way for transmitting visual information to the brain. There are three primary types of photoreceptors: [[Cone cell|Cones]] are photoreceptors that respond significantly to [[color]].  In humans the three different types of cones correspond with a primary response to short wavelength (blue), medium wavelength (green), and long wavelength (yellow/red).<ref name="Encyclopædia Britannica 2010">"eye, human." Encyclopædia Britannica. Encyclopædia Britannica Ultimate Reference Suite. Chicago: Encyclopædia Britannica, 2010.</ref> [[Rod cell|Rods]] are photoreceptors that are very sensitive to the intensity of light, allowing for vision in dim lighting.  The concentrations and ratio of rods to cones is strongly correlated with whether an animal is [[Diurnality|diurnal]] or [[nocturnal]].  In humans, rods outnumber cones by approximately 20:1, while in nocturnal animals, such as the [[tawny owl]], the ratio is closer to 1000:1.<ref name="Encyclopædia Britannica 2010" /> [[Retinal ganglion cell]]s are involved in the [[sympathetic response]]. Of the ~1.3 million ganglion cells present in the retina, 1-2% are believed to be photosensitive.<ref>{{cite journal |vauthors=Foster RG, Provencio I, Hudson D, Fiske S, De Grip W, Menaker M |title=Circadian photoreception in the retinally degenerate mouse (rd/rd) |journal=J Comp Physiol A |volume=169 |issue=1 |pages=39–50 |date=July 1991 |pmid=1941717 |doi=10.1007/BF00198171 }}</ref>

Issues and decay of sensory neurons associated with vision lead to disorders such as:
#  [[Macular degeneration]] – degeneration of the central visual field due to either cellular debris or blood vessels accumulating between the retina and the choroid, thereby disturbing and/or destroying the complex interplay of neurons that are present there.<ref>{{Cite journal|last=de Jong|first=Paulus T.V.M.|date=2006-10-05|title=Age-Related Macular Degeneration|journal=New England Journal of Medicine|volume=355|issue=14|pages=1474–1485|doi=10.1056/NEJMra062326|issn=0028-4793|pmid=17021323}}</ref>
#  [[Glaucoma]] – loss of retinal ganglion cells which causes some loss of vision to blindness.<ref>{{Cite book|title=Clinical methods : the history, physical, and laboratory examinations|last1=Alguire|first1=Patrick|last2=Dallas|first2=Wilbur|last3=Willis|first3=John|last4=Kenneth|first4=Henry|publisher=Butterworths|year=1990|isbn=978-0409900774|edition=3rd|chapter=Ch. 118 Tonometry|oclc=15695765}}</ref>
#  [[Diabetic retinopathy]] – poor blood sugar control due to diabetes damages the tiny blood vessels in the retina.<ref>{{Cite web|url=https://nihseniorhealth.gov/diabeticretinopathy/causesandriskfactors/01.html|title=NIHSeniorHealth: Diabetic Retinopathy - Causes and Risk Factors|website=nihseniorhealth.gov|access-date=2016-12-19|archive-url=https://web.archive.org/web/20170114062500/https://nihseniorhealth.gov/diabeticretinopathy/causesandriskfactors/01.html|archive-date=2017-01-14|url-status=dead}}</ref>