Neuroscience: Exploring the Brain - Chapter 9 Key Terms Flashcards

Chapter 9 Key Terms and Definitions

5030733827	vision	The sense of sight	0
5030733828	retina	A thin layer of cells at the back of the eye that transduces light energy into neural activity	1
5030733829	refraction	The bending of light rays that can occur when they travel from one transparent medium to another	2
5030733830	pupil	The opening that allows light to enter the eye and strike the retina	3
5030733831	iris	The circular, pigmented muscle that controls the size of the pupil in the eye	4
5030733832	cornea	The transparent external surface of the eye	5
5030733833	sclera	The tough outer wall of the eyeball; the white of the eye	6
5030733834	extraocular muscle	A muscle that moves the eye in the orbit	7
5030733835	conjunctiva	The membrane that folds back from the eyelids and attaches to the sclera of the eye	8
5030733836	optic nerve	The bundle of ganglion cell axons that passes from the eye to the optic chiasm	9
5030733837	optic disk	The location on the retina where optic nerve axons leaves the eye	10
5030733838	macula	In the eye, a yellowish spot in the middle of the retina with relatively few large blood vessels; contains the fovea	11
5030733839	fovea	The pit or depression in the retina at the center of the macula; in humans, the fovea contains only cone photoreceptors and is specialized for high-acuity vision	12
5030733840	aqueous humor	The fluid between the cornea and the lens of the eye	13
5030733841	lens	The transparent structure lying between the aqueous humor and the vitreous humor the enables the eye to adjust its focus to different viewing distances	14
5030733842	ciliary muscle	A muscle that controls the shape of the eye's lens	15
5030733843	vitreous humor	The jellylike substance filling the eye between the lens and the retina	16
5030733844	diopter	A unit of measurement for the refractive power of the eye, the reciprocal of the focal distance	17
5030733845	accommodation	The focusing of light by changing the shape of the eye's lens	18
5030733846	pupillary light reflex	An adjustment by the pupil to different levels of ambient light; the pupil's diameter becomes larger in dim light and smaller in bright light, in repsonse to retinal inputs to brain stem neurons that control the iris	19
5030733847	visual field	The total region of space viewed by both eyes when the eyes are fixated on a point	20
5030733848	visual acuity	The ability of the visual system to distinguish between two nearby points	21
5030733849	visual angle	A way to describe distance across the retina; an object that subtends and angles of 3.5° will form an image on the retina that is 1mm across	22
5030733850	photoreceptor	A specialized cell in the retina that transduces light energy into changes in membrane potential	23
5030733851	bipolar cell	In the retina, a cell that connects photoreceptors to ganglion cells	24
5030733852	ganglion cell	A cell in the retina that receives input from bipolar cells and sends an axon into the optic nerve	25
5030733853	horizontal cell	A cell in the retina of the eye that projects neurites laterally in the outer plexiform layer	26
5030733854	amacrine cell	A neuron in the retina of the eye that projects neurites laterally in the inner plexiform layer	27
5030733855	ganglion cell layer	A layer of the retina closest to the center of the eye, containing ganglion cells	28
5030733856	inner nuclear layer	A layer of the retina of the eye containing the cell bodies of bipolar, horizontal, and amacrime cells	29
5030733857	outer nuclear layer	A layer of the retina of the eye containing the cell bodies of photoreceptors	30
5030733858	layer of photoreceptor outer segments	A layer of the retina farthest from the center of the eye containing the light-sensitive elements of the photoreceptors	31
5030733859	inner plexiform layer	A layer of the retina of the eye, located between the ganglion cell layer and the inner nuclear layer; contains the neurites and synapses between bipolar cells, amacrine cells, and ganglion cells	32
5030733860	outer plaxiform layer	A layer of the retina of the eye, between the inner nuclear layer and the outer nuclear layer; contains the neurites and synapses between photoreceptors, horizontal cells, and bipolar cells	33
5030733861	rod photoreceptor	A photoreceptor in the retina containing rhodopsin and specialized for low light levels	34
5030733862	cone photoreceptor	A photoreceptor in the retina containing one of three photopigments that are maximally sensitive to different wavelengths of light. Cones are concentrated in the fovea, specialized for daytime vision, and responsible for all color vision	35
5030733863	dark current	The inward sodium current that occurs in photoreceptors in the dark	36
5030733864	cyclic guanosine monophosphate (cGMP)	A second messenger formed from guanosine triphosphate by the action of the enzyme guanylyl cyclase	37
5030733865	rhodopsin	The photopigment in rod photoreceptors	38
5030733866	transducin	The G-protein that couples rhodopsin to the enzyme phosphodiesterase in rod photoreceptors	39
5030733867	phosphodiesterase (PDE)	An enzyme that breaks down the cyclic nucleotide second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)	40
5030733868	Young-Helmholtz trichromacy theory	The theory that the brain assign colors based on a comparison of the readout of the three types of cone photoreceptors	41
5030733869	dark adaptation	The process by which the retina becomes more sensitive to light in dim light	42
5030733870	light adaptation	The process by which the retina becomes less sensitive to light in bright light conditions	43
5030733871	OFF bipolar cell	A bipolar cell of the retina that depolarizes in response to dark (light OFF) in the center of its receptive field	44
5030733872	ON bipolar cell	A bipolar cell of the retina that depolarizes in response to light (light ON) in the center of its receptive field	45
5030733873	receptive field	The region of a sensory surface (retina, skin) that, when stimulated, changes the membrane potential of a neuron	46
5030733874	center-surround receptive field	A visual receptive field with a circular center region and a surround region forming a ring around the center; stimulation of the center produces a response opposite that generated by stimulation of the surround	47
5030733875	M-type ganglion cell	A type of ganglion cell in the retina characterized by a large cell body and dendritic arbor, a transient response to light, and no sensitivity to different wavelengths of light; also called M cell	48
5030733876	P-type ganglion cell	A type of ganglion cell in the retina characterized by a small cell body and dendritic arbor, a sustained response to light, and sensitivity to different wavelengths of light; also called P cell	49
5030733877	nonM-nonP ganglion cell	A ganglion cell in the retina that is not of the M type or P type, based on cell morphology and response properties. Of the variety of cell types in this category, some are known to be sensitive to the wavelength of light	50
5030733878	color-opponent cell	A cell in the visual system with an excitatory response to wavelengths of light of one color and an inhibitory response to wavelengths of another color; the color pairs that cancel each other are red-green and blue-yellow	51
5030733879	parallel processing	The idea that different stimulus attributes are processed by the brain is parallel, using distinct pathways	52