EYE 2
... Bleaching causes excess Na+ channels to close (resting potential is more –ve) 120mV Less neurotransmitter is released at the bipolar synapse This stops the inhibition of the bipolar cell A generator potential is formed in the bipolar cell If threshold is reached in the bipolar cell (through a summat ...
... Bleaching causes excess Na+ channels to close (resting potential is more –ve) 120mV Less neurotransmitter is released at the bipolar synapse This stops the inhibition of the bipolar cell A generator potential is formed in the bipolar cell If threshold is reached in the bipolar cell (through a summat ...
Special Senses: Vision
... Choroid – dark internal layer of eye; keeps light from scattering in eye, keeps inside of eye dark. ...
... Choroid – dark internal layer of eye; keeps light from scattering in eye, keeps inside of eye dark. ...
Why our eyes are wir..
... the glial cells were green to red, which the eye needs most for daytime vision. The eye usually receives too much blue - and thus has fewer blue-sensitive cones. Further computer simulations showed that green and red are concentrated five to ten times more by the glial cells, and into their respecti ...
... the glial cells were green to red, which the eye needs most for daytime vision. The eye usually receives too much blue - and thus has fewer blue-sensitive cones. Further computer simulations showed that green and red are concentrated five to ten times more by the glial cells, and into their respecti ...
Short Course in the Physiology of Vision
... (interconnecting layers) transmit nerve impulses from the 120 million individual rods and cones to the ganglion cells. Each of 6 million retinal ganglion cells supplies a single axon (nerve fiber) that travels through the optic nerve to the brain. Ganglion cells transmit information regarding color, ...
... (interconnecting layers) transmit nerve impulses from the 120 million individual rods and cones to the ganglion cells. Each of 6 million retinal ganglion cells supplies a single axon (nerve fiber) that travels through the optic nerve to the brain. Ganglion cells transmit information regarding color, ...
ppt - CSUS
... ● Photoreceptors: light-sensitive cells – they send neural signals when light hits them ● photopigment: molecule that transforms when light hits it ● Rods: contain photopigment rhodopsin (sensitive to a broad range of light) - only allows black and white vision ● Cones: contain three different photo ...
... ● Photoreceptors: light-sensitive cells – they send neural signals when light hits them ● photopigment: molecule that transforms when light hits it ● Rods: contain photopigment rhodopsin (sensitive to a broad range of light) - only allows black and white vision ● Cones: contain three different photo ...
Sensory Physiology
... High level of illumination Not very sensitive to light See in color Precise detail Little convergence Mostly in center of retina, esp. fovea ...
... High level of illumination Not very sensitive to light See in color Precise detail Little convergence Mostly in center of retina, esp. fovea ...
Vision
... Biochemical cascade and light adaptation Biochemical cascade initiated by photon capture greatly amplifies signal: Estimated that 1 light activated rhodopsin molecule can activate 800 transducin molecules. Each transducin molecule activates only 1 phosphodiesterase molecule but each of these may ca ...
... Biochemical cascade and light adaptation Biochemical cascade initiated by photon capture greatly amplifies signal: Estimated that 1 light activated rhodopsin molecule can activate 800 transducin molecules. Each transducin molecule activates only 1 phosphodiesterase molecule but each of these may ca ...
The eye and color notes (1)
... eye where light enters. • Iris: a ring of muscle tissue that forms the colored portion of the eye around the pupil. • Lens: structure behind the pupil that changes shape to help focus images. • Retina: The light-sensitive inner surface of the eye, contains receptor rods and is the area where informa ...
... eye where light enters. • Iris: a ring of muscle tissue that forms the colored portion of the eye around the pupil. • Lens: structure behind the pupil that changes shape to help focus images. • Retina: The light-sensitive inner surface of the eye, contains receptor rods and is the area where informa ...
2.8 notes
... – Visual accommodation • Change in the thickness of lens • Eye focuses on objects that are far away or close ...
... – Visual accommodation • Change in the thickness of lens • Eye focuses on objects that are far away or close ...
1) It turned out that an antibiotic furosemide selectively destroys
... 9) A difference between rods and cones is: a. Rods hyperpolarize to light, while cones depolarize to light b. Cones do not use the effector enzyme phosphodiesterase c. Cones and rods use different types of opsins d. Only cones contain retinal 10) One type of bipolar cells contains a special receptor ...
... 9) A difference between rods and cones is: a. Rods hyperpolarize to light, while cones depolarize to light b. Cones do not use the effector enzyme phosphodiesterase c. Cones and rods use different types of opsins d. Only cones contain retinal 10) One type of bipolar cells contains a special receptor ...
Basic Visual Processes
... array is a very good optimized match for the eye’s optics. In other words, the organization of receptors is as good as, but no better than, the eye’s optics •There are significant differences between L and M cones and S cones. Again, though, these differences match the way that the eye’s optics resp ...
... array is a very good optimized match for the eye’s optics. In other words, the organization of receptors is as good as, but no better than, the eye’s optics •There are significant differences between L and M cones and S cones. Again, though, these differences match the way that the eye’s optics resp ...
S & P Day 1a
... 3. Behind the pupil, the lens, a transparent structure, changes its curvature in a process called accomodation, and focuses the light rays into an image on the light-sensitive back surface called the retina: where image is focused. ...
... 3. Behind the pupil, the lens, a transparent structure, changes its curvature in a process called accomodation, and focuses the light rays into an image on the light-sensitive back surface called the retina: where image is focused. ...
Vascular layer
... 2 OBLIQUE (superior and inferior oblique) muscles produce more complex movements as well as slight rotation of the eyeball -Allows us to look “out and up” (lateral/superior) or “down and in” (medial/inferior) •CN IV (trochlear nerve) = superior oblique (tendon passes through the TROCHLEA) •CN VI (a ...
... 2 OBLIQUE (superior and inferior oblique) muscles produce more complex movements as well as slight rotation of the eyeball -Allows us to look “out and up” (lateral/superior) or “down and in” (medial/inferior) •CN IV (trochlear nerve) = superior oblique (tendon passes through the TROCHLEA) •CN VI (a ...
Retinal Nuclei
... -> Has cells fire in direct proportion to the total amount of light (presumably not center-surround!). -> In animals lesioning this area causes disturbances of diurnal rhythms. -> Visual inputs entrain the natural rhythm in the SCN. -> Only other known clock in the human body is in the retina itself ...
... -> Has cells fire in direct proportion to the total amount of light (presumably not center-surround!). -> In animals lesioning this area causes disturbances of diurnal rhythms. -> Visual inputs entrain the natural rhythm in the SCN. -> Only other known clock in the human body is in the retina itself ...
2320Lecture8
... Using Light • Light is focused on the retina by the curvature of the cornea and the lens • Constriction of the pupil limits how much light gets in AND reduces the amount of focusing required of the lens ...
... Using Light • Light is focused on the retina by the curvature of the cornea and the lens • Constriction of the pupil limits how much light gets in AND reduces the amount of focusing required of the lens ...
Ch 13 – PNS continued
... a) ___________ layer – the outer layer that absorbs light and prevents its ...
... a) ___________ layer – the outer layer that absorbs light and prevents its ...
Basic Ocular Anatomy
... cones. •! Rods: night-time vision, very sensitive at dim light level, no rods in the fovea. •! Cones: daytime vision, not as sensitive as rods but work well in bright light, most densely packed in the fovea. Three cone types provide trichromatic (color) vision. ...
... cones. •! Rods: night-time vision, very sensitive at dim light level, no rods in the fovea. •! Cones: daytime vision, not as sensitive as rods but work well in bright light, most densely packed in the fovea. Three cone types provide trichromatic (color) vision. ...
Low-level Vision
... Blind spot: nasal to fovea, where optic nerve fibers leave retina: no photoreceptor Cones: detect color. 3 varieties: RGB, not very sensitive, day vision Rods: low light gray-scale receptors. 10 times as many as cones, (108) Cones: less sensitive, faster response, directionally sensitive, connected ...
... Blind spot: nasal to fovea, where optic nerve fibers leave retina: no photoreceptor Cones: detect color. 3 varieties: RGB, not very sensitive, day vision Rods: low light gray-scale receptors. 10 times as many as cones, (108) Cones: less sensitive, faster response, directionally sensitive, connected ...
(Eye socket).
... A retinal rod is cylindrical in shape, measuring about 50 microns with a diameter of 2 microns. Each retina contains about 130 million (20 times the number of Cones). ...
... A retinal rod is cylindrical in shape, measuring about 50 microns with a diameter of 2 microns. Each retina contains about 130 million (20 times the number of Cones). ...
Lecture notes - (canvas.brown.edu).
... Retina as brain Cross section: layers Backwards light path (passes through inner retina before hitting photoreceptors) Receptors Rods vs. Cones Membranous disks of outer segments Photopigment Hyperpolarizing light response Bipolars Connect outer to inner retina Ganglion cells Output cells; have axon ...
... Retina as brain Cross section: layers Backwards light path (passes through inner retina before hitting photoreceptors) Receptors Rods vs. Cones Membranous disks of outer segments Photopigment Hyperpolarizing light response Bipolars Connect outer to inner retina Ganglion cells Output cells; have axon ...
Ch 13 – PNS continued
... a) ___________ layer – the outer layer that absorbs light and prevents its ...
... a) ___________ layer – the outer layer that absorbs light and prevents its ...
The Physiology of Vision
... reaching the lateral genicualte body of the thalamus. • Fibers from each nasal (medial) hemiretina decussate in the optic chiasm . • Fibers from the temporal ( lateral) hemiretina do not decussate. • In the geniculate body , fibers from one nasal hemiretina synapse with the temporal fibers of the ot ...
... reaching the lateral genicualte body of the thalamus. • Fibers from each nasal (medial) hemiretina decussate in the optic chiasm . • Fibers from the temporal ( lateral) hemiretina do not decussate. • In the geniculate body , fibers from one nasal hemiretina synapse with the temporal fibers of the ot ...
Sensation question WS - Coral Gables Senior High
... 9. Which nerve fibers, small or large, block the message of pain to the brain? 10. The minimum stimulus you can detect 50% of the time is called the ___ ? 11. The process by which your brain organizes and interprets information ____ 12. Why don’t images disappear if you look at them constantly? 13. ...
... 9. Which nerve fibers, small or large, block the message of pain to the brain? 10. The minimum stimulus you can detect 50% of the time is called the ___ ? 11. The process by which your brain organizes and interprets information ____ 12. Why don’t images disappear if you look at them constantly? 13. ...
Photoreceptor cell
A photoreceptor cell is a specialized type of neuron found in the retina that is capable of phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in the cell absorb photons, triggering a change in the cell's membrane potential.The two classic photoreceptor cells are rods and cones, each contributing information used by the visual system to form a representation of the visual world, sight. The rods are narrower than the cones and distributed differently across the retina, but the chemical process in each that supports phototransduction is similar. A third class of photoreceptor cells was discovered during the 1990s: the photosensitive ganglion cells. These cells do not contribute to sight directly, but are thought to support circadian rhythms and pupillary reflex.There are major functional differences between the rods and cones. Rods are extremely sensitive, and can be triggered by a single photon. At very low light levels, visual experience is based solely on the rod signal. This explains why colors cannot be seen at low light levels: only one type of photoreceptor cell is active.Cones require significantly brighter light (i.e., a larger numbers of photons) in order to produce a signal. In humans, there are three different types of cone cell, distinguished by their pattern of response to different wavelengths of light. Color experience is calculated from these three distinct signals, perhaps via an opponent process. The three types of cone cell respond (roughly) to light of short, medium, and long wavelengths. Note that, due to the principle of univariance, the firing of the cell depends upon only the number of photons absorbed. The different responses of the three types of cone cells are determined by the likelihoods that their respective photoreceptor proteins will absorb photons of different wavelengths. So, for example, an L cone cell contains a photoreceptor protein that more readily absorbs long wavelengths of light (i.e., more ""red""). Light of a shorter wavelength can also produce the same response, but it must be much brighter to do so.The human retina contains about 120 million rod cells and 6 million cone cells. The number and ratio of rods to cones varies among species, dependent on whether an animal is primarily diurnal or nocturnal. Certain owls, such as the tawny owl, have a tremendous number of rods in their retinae. In addition, there are about 2.4 million to 3 million ganglion cells in the human visual system, the axons of these cells form the 2 optic nerves, 1 to 2% of them photosensitive.The pineal and parapineal glands are photoreceptive in non-mammalian vertebrates, but not in mammals. Birds have photoactive cerebrospinal fluid (CSF)-contacting neurons within the paraventricular organ that respond to light in the absence of input from the eyes or neurotransmitters. Invertebrate photoreceptors in organisms such as insects and molluscs are different in both their morphological organization and their underlying biochemical pathways. Described here are human photoreceptors.