-eyelashes are richly innervated and triggers reflex blinking
|
|
- Kerry Harvey
- 6 years ago
- Views:
Transcription
1 The Eye and Vision -vision is the dominant sense -70% of all sensory receptors in the body are in the eyes -half of the cerebral cortex is involved in some aspect of visual processing -accessory structures protect the eye or aid its function: 1) Eyebrows -short, coarse hairs that overlie the supraorbital margins of the skull -help to shade the eyes from sunlight -prevent perspiration fro reaching the eyes -contraction of the orbicularis muscle depresses the eyebrow -contraction of the corrugator muscle moves the eyebrow medially 2) Eyelids -known as the palpebrae -protect the eyes anteriorly -eyelids are separated by the palpebral fissure and meet at the medial and lateral commisures -tarsal plates support it internally and anchor the orbicularis oculi and the levator palpebrae superioris muscles that run within the eyelid -the upper eyelid is more motile because the levator palpebrae superioris raises it to open the eye -eyelashes are richly innervated and triggers reflex blinking -tarsal glands are embedded in the tarsal plates and produce an oily secretion that lubricates the eyelid and the eye and prevents the eyelids from sticking together 3) Conjuctiva -a transparent mucous membrane that lines the eyelids (palpebral conjuctiva) and folds back over the anterior surface of the eyeball (bulbar conjuctiva) -the bulbar conjunctiva covers only the white of the eye and not the cornea -functions to produce a lubricating mucous that prevents the eyes form drying out -conjuctivitis is the inflammation of the conjucta and results in reddened, irritated eyes 4) Lacrimal Apparatus -consists of the lacrimal gland and the ducts that drain excess lacrimal secretions into the nasal cavity -the lacrimal gland lies in the orbit above the lateral end of the eye
2 -it continuously releases a dilute solution called lacrimal secretion (tears) -blinking spreads the tears downward and across the eyeball to the medial commisure, where they enter the paired lacrimal canaliculi via the lacrimal puncta (the red dot in the corner of your eye) -the tears drain into the lacrimal sac and then into the nasolacrimal duct, which empties into the nasal cavity at the inferior nasal meatus -lacrimal fluid contains mucus, antibodies, and lysozyme which is an enzyme that destroys bacteria -it helps cleanse and protect the eye surface, as well as moistening and lubricating it Extrinsic Eye Muscles -six strap-like extrinsic eye muscles control the movement of the eyeball -allows the eyes to follow a moving object and help maintain the shape of the eyeball and hold it in orbit -the 4 rectus muscles originate from the common tendinous ring (annular ring) located at the back of the orbit and run straight to their insertion on the eyeball -movements are indicated by their names: superior, inferior, lateral, and medial rectus muscles -the 2 oblique muscles move the eye in the vertical plane -the superior oblique muscle depresses the eye and turns it laterally -the inferior oblique muscle elevates the eye and turns it laterally -extrinsic eye muscles are the most precisely and rapidly controlled skeletal muscles in the body -reflected by their high axon-to-muscle fibre ration Structure of the Eyeball -the eyeball is an irregular sphere with an anterior pole and a posterior pole -its wall is composed of a fibrous layer, a vascular layer, and inner layers -the internal cavity is filled with fluids known as humors that help to maintain its shape -anterior portion = aqueous humor -forms and drains continuously -supplies nutrients and oxygen to the lens and cornea and carries away metabolic wastes -posterior portion = vitreous humor -helps transmit light, support the posterior surface of the lens and hold the neural retina firmly against the pigmented layer, and contributes to intraocular pressure (helps counteract the pulling force of the extrinsic eye muslces)
3 -the lens acts as the adjustable focusing apparatus of the eye and is supported vertically within the eyeball, dividing it into anterior and posterior segments Layers Forming the Wall of the Eyeball 1) Fibrous Layer -outermost coat of the eye -made up of the sclera (white of the eye) and the cornea (lets light enter the eye and is a major part of the light bending apparatus of the eye) 2) Vascular Layer -middle coat of the eyeball -known as the uvea -made up of the choroid, ciliary body, and the iris -the choroid is blood-vessel rich and supplies nutrition to all layers of the eyeball -contains brown pigment (produced by melanocytes) that helps absorb light, preventing it from scattering and reflecting within the eye -the ciliary body has ciliary muscles that control lens shape -the iris is the visible colored part of the eye and lies between the cornea and the lens -it has a round central opening known as the pupil which allows light to enter the eye -the iris is made up of 2 smooth muscle layers that act as a reflexively activated diaphragm to vary pupil size -in close vision and bright light, the sphincter pupillae (circular muscles) contract and the pupil constricts -in distant vision and dim light, the dilator pupillae (radial muscles) contract and the pupil dilates, allowing more light to enter the eye -pupillary dilation is controlled by sympathetic fibres -pupillary constriction is controlled by parasympathetic fibres -the iris contains only brown pigment; the amount of brown pigment determines eye color 3) Inner Layer (Retina) -two-layered -contains pigmented epithelial cells which makes up the outer layer -helps absorb light and prevent it from scattering -act as phagocytes to remove dead or damaged photoreceptor cells and store vitamin A needed by photoreceptor cells -contains the neural layer which makes up the inner layer -only the neural layer plays a direct role in vision -composed of photoreceptors, bipolar cells, and ganglion cells (from posterior to anterior)
4 ganglion -signals are produced in response to light and spread from the photoreceptors to the bipolar cells and then to the innermost cells, where action potentials are generated -ganglion axon cells run along the inner surface of the retina and leave the eye as the optic nerve -the optic nerve exits at the optic disc which lacks photoreceptors and is known as the blind spot -the brain "fills in" the information in order to deal with the absence of information -the retina contains photoreceptors that transduce / convert light energy, other neurons involved in the processing of light stimuli, and glia -rod cells are dim-light and peripheral vision receptors -more sensitive to light than cones and best suited for night vision -more numerous than cones -used for peripheral vision -absorb all wavelengths of visible light -perceived input is in gray tones only -the sum of all visual input feeds into a single ganglion cell -produces fuzzy, indistinct images since the visual cortex does not know which rod (out of the large number that influence a ganglion cell) -cone cells operate in bright light and provide precise, color vision -found in the macula lutea -concentrated in the fovea centralis -need bright light for activation and have low sensitivity -each cone in the fovea has a straight-through pathway to a ganglion cell -this accounts for detailed, high-resolution views of very small areas of the visual field provided by cones -because rods are absent from the foveae and cones do not respond to low-intensity light, we see dimly lit objects best when we do not look directly at them, and we recognize them when they move The Lens -biconvex, transparent, flexible structure -can change shape to allow precise focusing of light on the retina -avascular -made up of the lens epithelium and the lens fibres -the lens epithelium is confined to the anterior lens surface -consists of cuboidal cells that differentiate into the lens fibres -lens fibres make up the bulk of the lens
5 -contains transparent, precisely folded proteins called crystallins that form the body of the lens -the lens enlarges throughout life, becoming denser, more convex, and less elastic; this impairs its ability to focus light properly Physiology of Vision -electromagnetic radiation includes all energy waves, from long radio waves to very short gamma waves / X-rays -our eyes respond to the visible light portion of the spectrum -red waves are the longest waves and have the lowest energy -violet waves are the shortest and have the highest energy -objects have color because they absorb some wavelengths and reflect others -different cone receptor cells in the retina respond to different wavelengths of the visible spectrum -refraction involves bending of light rays as it meets the surface of a different medium at an oblique angle rather than a right angle Focusing Light on the Retina -light sequentially passes through the cornea, aqueous humor, the lens, the vitreous humor, and then passes through the entire thickness of the neural layer to excite the photoreceptors -light is refracted 3 times: 1) as it enters the cornea 2) entering the lens 3) leaving the lens -the lens curvature and elasticity can be actively changed to allow fine focusing of the image Focusing for Distant Vision -eyes are best adapted for distant vision -the far point of vision is the distance beyond which no change in lens shape (accommodation) is needed for focusing -for a normal (emmetropic) eye, the far point is 20 feet -during distant vision, ciliary muscles are completely relaxed and the lens is stretched flat -ciliary muscles are relaxed when sympathetic input to them increases and parasympathetic input decreases Focusing for Close Vision -light from close objects diverges as it approaches the eyes and it comes to a focal point farther from the lens
6 1) Accomodation -increases refractory power of the lens -ciliary muscles contract, providing a shorter focal length needed to focus the image of a close object on the retina -the closest point we can focus clearly on is known as the near point of vision and represents maximum bulge of the lens; near point of vision in the normal eye is 10 cm -a non-accommodating lens is known as presbyopia 2) Constriction -the sphincter pupillae muscles of the iris enhance the effect of accommodation by reducing the size of the pupil -this accommodation pupillary reflex prevents divergent light rays from entering the eye 3) Convergence -when we fixate on a close object, our eyes converge -convergence is the medial rotation of the eyeballs by the medial rectus muscles so that each is directed toward the object being viewed Myopia -occurs when distant objects are focused in front of the retina, rather then on it -distant objects are blurred -near-sightedness -corrected by concave lenses Hyperopia -far-sightedness -occurs when parallel light rays from distant objects are focused behind the retina -close objects are focused beyond the retina and appear blurry -corrected by convex lenses Photoreceptors and Phototransduction -photoreception is the process by which the eye detects light energy -phototransductiontion is the process by which light energy is converted into a graded receptor potential -photoreceptors are modified neurons The Chemistry of Visual Pigments -a light-absorbing molecule called retinal combines with proteins called opsin to form 4 types of visual pigments that absorbs different wavelengths of the visible spectrum -retinal can assume a variety of distinct 3-dimensional forms -when bound to opsin, it is known as 11-cis-retinal
7 -when 11-cis-retinal is struck by light and absorbs photons, it becomes all-transretinal -retinal twists into a new configuration and causes opsin to change shape and assume its activated form -rods and cones contain visual pigments (photopigments) -arranged in a stack of dislike infoldings of the plasma membrane that change shape as they absorb light 1) Excitation of Rods -the visual pigment of rods is a purple pigment called rhodopsin (11-cis-retinal + opsin) -rhodopsin forms and accumulates in the dark sequence of reactions -vitamin A is oxidized to 11-cis-retinal form and combines with opsin to form rhodopsin -when rhodopsin absorbs light, retinal changes to all-trans retinal; eventually the retinal-opsin combination breaks down and retinal and opsin separate -when the light-struck all-trans-retinal detaches from opsin, it is reconverted by enzymes within the pigmented epithelium to 11-cis-retinal -rhodopsin is regenerated when 11-cis-retinal is rejoined to opsin 2) Excitation of Cones -the breakdown and regeneration of pigments in cones is essentially the same as for rhodopsin -cones are less sensitive than rods and it takes a higher-intensity / brighter light to activate cones -cone opsins differ from rod opsins -naming of cones reflects the colors of light that each type of cone absorbs -blue cones, green cones, red cones -the perception of intermediate hues result from differential activation of more than one type of cone at the same time -when all cones are stimulated, we see white Light Transduction Reactions -when light triggers pigment breakdown, an enzymatic cascade occurs that results in closing cation channels that are normally kept open in the dark 1) light-activated rhodopsin activates a G protein called transducin -light energy first splits rhodopsin into all-trans retinal, releasing activated opsin -the freed opsin activates the G protein transducin
8 2) transducin activates PDE (phosphodiesterase) -PDE breaks down cgmp to GMP via hydrolysis -in the dark, cgmp binds to cation channels in the outer segments of photoreceptor cells, holding them open -this allows Na+ and Ca2+ to enter, depolarizing the cell to its dark potential (-40 mv)
9 -in the light, cgmp breaks down and the cation channels close -Na+ and Ca2+ stop entering the cell and it hyperpolarizes to about -70 mv; this stops inhibitory neurotransmitter from being released -no longer being inhibited, bipolar cells depolarize and release neurotransmitter onto ganglion cells, which is then converted into an action potential -the AP is transmitted to the brain along ganglion cell axons that make up the optic nerve -the hyperpolarization of photoreceptors is transmitted trough the retina and to the brain because photoreceptors / bipolar cells do not generate action potentials -photoreceptors and bipolar cells only generate graded potentials (i.e.: excitatory postsynaptic potentials and inhibitory postsynaptic potentials) -action potentials are used to carry information over long distances -retinal cells are small cells that are close together -graded potentials are adequate as signals that directly regulate neurotransmitter release at the synapse by opening or controlling voltagegated Ca2+
10 Light Adaptation -occurs when we move from darkness into bright light -rods and cones are strongly stimulated and large amounts of visual pigments are broken down instantaneously, producing a flood of signals that causes the glare -compensation occurs -all transducins move to the inner segment and this uncouples rhodopsin from the rest of the transduction cascade
11 -without transducin in the outer segment, the light hitting rhodopsin cannot produce a signal -as well, there is a switch from the rod to the cone system and other retinal neurons readily adapt, causing retinal sensitivity to decrease -the cones are now desensitized enough to take over -visual acuity and color vision improves -in general during light adaptation, retinal sensitivity (rod function) is lost and visual acuity is gained Dark Adaptation -the reverse of light adaptation -at first, we see all black because: -our cones stop functioning in low-intensity light (darkness) -our rod pigments have been bleached out by the bright light and the rods are still turned off -once we are in the dark: -rhodopsin accumulates -transducin returns to the outer segment -retinal sensitivity increases -dark adaptation is much slower than light adaptation -during light / dark adaptations, reflexive changes also occur in pupil size -bright light = pupil constriction -low light = pupil dilation -controlled by the pretectal nucleus of the midbrain and by parasympathetic fibres Visual Pathway to the Brain -axons of the retinal ganglion cells form the optic nerve -at the optic chiasma, fibres from the medial aspect of each eye cross-over (decussate) to the opposite side and continue via the optic tracts -each optic tract: -contains fibres from the lateral (temporal) aspect of the same eye and fibres from the medial (nasal) aspect of the opposite eye -carries all the information from the same half of the visual field -because the lens system of each eye reverses all images, the medial half of each retina receives light rays from the temporal part of the visual field and the lateral half of each retina receives an image of central part of the visual field
12 -paired optic tracts send most of their axons to synapse with neurons in the lateral geniculate nuclei of the thalamus -lateral geniculate nucleus maintains fibre separation and balances and combines the retinal input for delivery to the visual cortex -axons of the thalamic neurons project through the internal capsule to form the optic radiation of fibres in the cerebral white matter -these fibres project to the primary visual cortex in the occipital lobes, where conscious perception of visual images occurs -some nerve fibres in the optic tracts send branches to the midbrain -one set of fibres ends in the superior colliculi (visual reflex centers that control the extrinsic muscles of the eye and initiate visual reflexes) -another set of fibres project to the pretectal nuclei (mediates pupillary light reflexes) and to the suprachiasmatic nucleus (functions as the timer to set our daily biorhythms) -these fibres contain the visual pigment melanopsin (the circadian pigment) Depth Perception -achieved when both eyes view the same image from slightly different angles -the visual cortex fuses the slightly different images delivered by the 2 eyes -produces 3-D vision -depth perception depends on the 2 eyes working together -if only one eye is used, depth perception is lost and one must learn to judge position based on learned cues -animals have panamoric vision -eyes are placed more laterally so that visual fields overlap very little
13 Thalamic Processing -the lateral geniculate nuclei of the thalamus: -relays information on movement -segregates the retinal axons in preparation for depth perception -emphasizes visual inputs from the cones -sharpens the contrast information received from the retina Cortical Processing -there are 2 types of areas for processing retinal inputs on the visual cortex -the primary visual cortex (striate cortex) has processing neurons that respond to dark and bright edges (contrast information) and object orientation - the striate cortex provides form, color, and motion inputs to visual association areas (prestriate cortices) -anterior prestriate cortices continue the processing of visual information regarding form, color, and movement -complex visual processing extends forward into the temporal, parietal, and frontal lobes -the temporal lobe specializes in the identification of objects in the visual field -the parietal cortex and post-central gyrus uses information from the primary visual cortex to assess the spatial location of objects -this information is passed on to the frontal cortex to direct activities / guide movements
Coarse hairs that overlie the supraorbital margins Functions include: Shading the eye Preventing perspiration from reaching the eye
SPECIAL SENSES (INDERA KHUSUS) Dr.Milahayati Daulay Departemen Fisiologi FK USU Eye and Associated Structures 70% of all sensory receptors are in the eye Most of the eye is protected by a cushion of fat
More informationThe Special Senses: Vision
OLLI Lecture 5 The Special Senses: Vision Vision The eyes are the sensory organs for vision. They collect light waves through their photoreceptors (located in the retina) and transmit them as nerve impulses
More informationSpecial Senses: The Eye
Collin County Community College BIOL 2401: Week 9 Special Senses: The Eye 1 VISION As humans, we rely on Vision more than any other special sense. The eye itself is surrounded by accessory structures Eyelids
More informationPHGY Physiology. The Process of Vision. SENSORY PHYSIOLOGY Vision. Martin Paré. Visible Light. Ocular Anatomy. Ocular Anatomy.
PHGY 212 - Physiology SENSORY PHYSIOLOGY Vision Martin Paré Assistant Professor of Physiology & Psychology pare@biomed.queensu.ca http://brain.phgy.queensu.ca/pare The Process of Vision Vision is the process
More informationPHGY Physiology. SENSORY PHYSIOLOGY Vision. Martin Paré
PHGY 212 - Physiology SENSORY PHYSIOLOGY Vision Martin Paré Assistant Professor of Physiology & Psychology pare@biomed.queensu.ca http://brain.phgy.queensu.ca/pare The Process of Vision Vision is the process
More informationVisual System I Eye and Retina
Visual System I Eye and Retina Reading: BCP Chapter 9 www.webvision.edu The Visual System The visual system is the part of the NS which enables organisms to process visual details, as well as to perform
More information10/8/ dpt. n 21 = n n' r D = The electromagnetic spectrum. A few words about light. BÓDIS Emőke 02 October Optical Imaging in the Eye
A few words about light BÓDIS Emőke 02 October 2012 Optical Imaging in the Eye Healthy eye: 25 cm, v1 v2 Let s determine the change in the refractive power between the two extremes during accommodation!
More informationNovember 14, 2017 Vision: photoreceptor cells in eye 3 grps of accessory organs 1-eyebrows, eyelids, & eyelashes 2- lacrimal apparatus:
Vision: photoreceptor cells in eye 3 grps of accessory organs 1-eyebrows, eyelids, & eyelashes eyebrows: protection from debris & sun eyelids: continuation of skin, protection & lubrication eyelashes:
More informationSpecial Senses- THE EYE. Pages
Special Senses- THE EYE Pages 548-569 Accessory Structures Eyebrows Eyelids Conjunctiva Lacrimal Apparatus Extrinsic Eye Muscles EYEBROWS Deflect debris to side of face Facial recognition Nonverbal communication
More information11/23/11. A few words about light nm The electromagnetic spectrum. BÓDIS Emőke 22 November Schematic structure of the eye
11/23/11 A few words about light 300-850nm 400-800 nm BÓDIS Emőke 22 November 2011 The electromagnetic spectrum see only 1/70 of the electromagnetic spectrum The External Structure: The Immediate Structure:
More informationSensory receptors External internal stimulus change detectable energy transduce action potential different strengths different frequencies
General aspects Sensory receptors ; respond to changes in the environment. External or internal environment. A stimulus is a change in the environmental condition which is detectable by a sensory receptor
More informationSpecial Senses. Important Concepts. Anatomy of the Eye. Anatomy of the Eye. Biol 219 Lecture 17 Vision Fall The Eye and Vision
Special Senses The Eye and Vision Important Concepts Describe the structures of the eye and the role of each structure in vision. Trace the pathway for vis ion from the retina to the visual cortex. Explain
More informationVision. By. Leanora Thompson, Karen Vega, and Abby Brainerd
Vision By. Leanora Thompson, Karen Vega, and Abby Brainerd Anatomy Outermost part of the eye is the Sclera. Cornea transparent part of outer layer Two cavities by the lens. Anterior cavity = Aqueous humor
More informationEYE ANATOMY. Multimedia Health Education. Disclaimer
Disclaimer This movie is an educational resource only and should not be used to manage your health. The information in this presentation has been intended to help consumers understand the structure and
More information1. Introduction to Anatomy of the Eye and its Adnexa
1. Introduction to Anatomy of the Eye and its Adnexa Fig 1: A Cross section of the human eye. Let us imagine we are traveling with a ray of light into the eye. The first structure we will encounter is
More informationThe Eye. Nakhleh Abu-Yaghi, M.B.B.S Ophthalmology Division
The Eye Nakhleh Abu-Yaghi, M.B.B.S Ophthalmology Division Coats of the Eyeball 1- OUTER FIBROUS COAT is made up of : Posterior opaque part 2-THE SCLERA the dense white part 1- THE CORNEA the anterior
More informationChapter Six Chapter Six
Chapter Six Chapter Six Vision Sight begins with Light The advantages of electromagnetic radiation (Light) as a stimulus are Electromagnetic energy is abundant, travels VERY quickly and in fairly straight
More information4Basic anatomy and physiology
Hene_Ch09.qxd 8/30/04 6:51 AM Page 348 348 4Basic anatomy and physiology The eye is a highly specialized organ with an average axial length of 24 mm and a volume of 6.5 ml. Except for its anterior aspect,
More informationVision. By: Karen, Jaqui, and Jen
Vision By: Karen, Jaqui, and Jen Activity: Directions: Stare at the black dot in the center of the picture don't look at anything else but the black dot. When we switch the picture you can look around
More informationIII: Vision. Objectives:
III: Vision Objectives: Describe the characteristics of visible light, and explain the process by which the eye transforms light energy into neural. Describe how the eye and the brain process visual information.
More informationiris pupil cornea ciliary muscles accommodation Retina Fovea blind spot
Chapter 6 Vision Exam 1 Anatomy of vision Primary visual cortex (striate cortex, V1) Prestriate cortex, Extrastriate cortex (Visual association coretx ) Second level association areas in the temporal and
More informationTHE EYE. People of Asian descent have an EPICANTHIC FOLD in the upper eyelid; no functional difference.
THE EYE The eye is in the orbit of the skull for protection. Within the orbit are 6 extrinsic eye muscles, which move the eye. There are 4 cranial nerves: Optic (II), Occulomotor (III), Trochlear (IV),
More informationEye. Eye Major structural layer of the wall of the eye is a thick layer of dense C.T.; that layer has two parts:
General aspects Sensory receptors ; External or internal environment. A stimulus is a change in the environmental condition which is detectable by a sensory receptor 1 Major structural layer of the wall
More informationObjectives. 3. Visual acuity. Layers of the. eye ball. 1. Conjunctiva : is. three quarters. posteriorly and
OCULAR PHYSIOLOGY (I) Dr.Ahmed Al Shaibani Lab.2 Oct.2013 Objectives 1. Review of ocular anatomy (Ex. after image) 2. Visual pathway & field (Ex. Crossed & uncrossed diplopia, mechanical stimulation of
More informationEYE STRUCTURE AND FUNCTION
Name: Class: Date: EYE STRUCTURE AND FUNCTION The eye is the body s organ of sight. It gathers light from the environment and forms an image on specialized nerve cells on the retina. Vision occurs when
More informationSlide 4 Now we have the same components that we find in our eye. The analogy is made clear in this slide. Slide 5 Important structures in the eye
Vision 1 Slide 2 The obvious analogy for the eye is a camera, and the simplest camera is a pinhole camera: a dark box with light-sensitive film on one side and a pinhole on the other. The image is made
More informationAP PSYCH Unit 4.2 Vision 1. How does the eye transform light energy into neural messages? 2. How does the brain process visual information? 3.
AP PSYCH Unit 4.2 Vision 1. How does the eye transform light energy into neural messages? 2. How does the brain process visual information? 3. What theories help us understand color vision? 4. Is your
More information2 The First Steps in Vision
2 The First Steps in Vision 2 The First Steps in Vision A Little Light Physics Eyes That See light Retinal Information Processing Whistling in the Dark: Dark and Light Adaptation The Man Who Could Not
More informationEarly Visual Processing: Receptive Fields & Retinal Processing (Chapter 2, part 2)
Early Visual Processing: Receptive Fields & Retinal Processing (Chapter 2, part 2) Lecture 5 Jonathan Pillow Sensation & Perception (PSY 345 / NEU 325) Princeton University, Spring 2015 1 Summary of last
More informationThe Eye. Morphology of the eye (continued) Morphology of the eye. Sensation & Perception PSYC Thomas E. Van Cantfort, Ph.D
Sensation & Perception PSYC420-01 Thomas E. Van Cantfort, Ph.D The Eye The Eye The function of the eyeball is to protect the photoreceptors The role of the eye is to capture an image of objects that we
More informationVision. The eye. Image formation. Eye defects & corrective lenses. Visual acuity. Colour vision. Lecture 3.5
Lecture 3.5 Vision The eye Image formation Eye defects & corrective lenses Visual acuity Colour vision Vision http://www.wired.com/wiredscience/2009/04/schizoillusion/ Perception of light--- eye-brain
More informationThe Eye. (We ll leave the Lord Sauron jokes to you.)
The Eye (We ll leave the Lord Sauron jokes to you.) When you look in the mirror, you only see a very small part of your eyes. In reality, they are incredibly complex organs with a pretty big job: enabling
More information25 Things To Know. Vision
25 Things To Know Vision Magnetism Electromagnetic Energy Electricity Magnetism Electromagnetic Energy Electricity Light Frequency Amplitude Light Frequency How often it comes Wave length Peak to peak
More informationBy Dr. Abdelaziz Hussein
By Dr. Abdelaziz Hussein Light is a form of radiant energy, consisting of electromagnetic waves a. Velocity of light: In air it is 300,000 km/second. b. Wave length: The wave-length of visible light to
More informationBIOPHYSICS OF VISION GEOMETRIC OPTICS OF HUMAN EYE. Refraction media of the human eye. D eye = 63 diopter, D cornea =40, D lens = 15+
BIOPHYSICS OF VISION THEORY OF COLOR VISION ELECTRORETINOGRAM Two problems: All cows are black in dark! Playing tennis in dark with illuminated lines, rackets, net, and ball! Refraction media of the human
More informationThe eye* The eye is a slightly asymmetrical globe, about an inch in diameter. The front part of the eye (the part you see in the mirror) includes:
The eye* The eye is a slightly asymmetrical globe, about an inch in diameter. The front part of the eye (the part you see in the mirror) includes: The iris (the pigmented part) The cornea (a clear dome
More informationLECTURE 2. Vision Accomodation& pupillary light reflex By Prof/Faten zakareia
LECTURE 2 Vision Accomodation& pupillary light reflex By Prof/Faten zakareia Objectives: At the end of this lecture,the student should be able to;- -Describe visual acuity & depth perception -Contrast
More informationSensation. What is Sensation, Perception, and Cognition. All sensory systems operate the same, they only use different mechanisms
Sensation All sensory systems operate the same, they only use different mechanisms 1. Have a physical stimulus (e.g., light) 2. The stimulus emits some sort of energy 3. Energy activates some sort of receptor
More informationSensation. Sensation. Perception. What is Sensation, Perception, and Cognition
All sensory systems operate the same, they only use different mechanisms Sensation 1. Have a physical stimulus (e.g., light) 2. The stimulus emits some sort of energy 3. Energy activates some sort of receptor
More informationChapter 2: The Beginnings of Perception
Chapter 2: The Beginnings of Perception We ll see the first three steps of the perceptual process for vision https:// 49.media.tumblr.co m/ 87423d97f3fbba8fa4 91f2f1bfbb6893/ tumblr_o1jdiqp4tc1 qabbyto1_500.gif
More informationTopic 4: Lenses and Vision. Lens a curved transparent material through which light passes (transmit) Ex) glass, plastic
Topic 4: Lenses and Vision Lens a curved transparent material through which light passes (transmit) Ex) glass, plastic Double Concave Lenses Are thinner and flatter in the middle than around the edges.
More informationVisual Optics. Visual Optics - Introduction
Visual Optics Jim Schwiegerling, PhD Ophthalmology & Optical Sciences University of Arizona Visual Optics - Introduction In this course, the optical principals behind the workings of the eye and visual
More informationABO Certification Training. Part I: Anatomy and Physiology
ABO Certification Training Part I: Anatomy and Physiology Major Ocular Structures Centralis Nerve Major Ocular Structures The Cornea Cornea Layers Epithelium Highly regenerative: Cells reproduce so rapidly
More informationPSY 214 Lecture # (09/14/2011) (Introduction to Vision) Dr. Achtman PSY 214. Lecture 4 Topic: Introduction to Vision Chapter 3, pages 44-54
Corrections: A correction needs to be made to NTCO3 on page 3 under excitatory transmitters. It is possible to excite a neuron without sending information to another neuron. For example, in figure 2.12
More informationBiology 70 Slides for Lecture 1 Fall 2007
Biology 70 Part II Sensory Systems www.biology.ucsc.edu 1 2 intensity vs spatial position (image formation) color 3 4 motion depth (monocular) 5 6 1 depth (binocular) 1. In the lectures on perception we
More informationRetina. Convergence. Early visual processing: retina & LGN. Visual Photoreptors: rods and cones. Visual Photoreptors: rods and cones.
Announcements 1 st exam (next Thursday): Multiple choice (about 22), short answer and short essay don t list everything you know for the essay questions Book vs. lectures know bold terms for things that
More informationChapter 6 Human Vision
Chapter 6 Notes: Human Vision Name: Block: Human Vision The Humane Eye: 8) 1) 2) 9) 10) 4) 5) 11) 12) 3) 13) 6) 7) Functions of the Eye: 1) Cornea a transparent tissue the iris and pupil; provides most
More informationEYE. The eye is an extension of the brain
I SEE YOU EYE The eye is an extension of the brain Eye brain proxomity Can you see : the optic nerve bundle? Spinal cord? The human Eye The eye is the sense organ for light. Receptors for light are found
More informationHandout G: The Eye and How We See
Handout G: The Eye and How We See Prevent Blindness America. (2003c). The eye and how we see. Retrieved July 31, 2003, from http://www.preventblindness.org/resources/howwesee.html Your eyes are wonderful
More informationBiophysics of the senses: vision
Medical Physics I. Biophysics of the senses: vision Ferenc Bari Professor & chairman Department of Medical Physics & Informatics Szeged, December 3, 2015. Basic properties of light Visible electromagnetic
More informationScience 8 Unit 2 Pack:
Science 8 Unit 2 Pack: Name Page 0 Section 4.1 : The Properties of Waves Pages By the end of section 4.1 you should be able to understand the following: Waves are disturbances that transmit energy from
More informationHW- Finish your vision book!
March 1 Table of Contents: 77. March 1 & 2 78. Vision Book Agenda: 1. Daily Sheet 2. Vision Notes and Discussion 3. Work on vision book! EQ- How does vision work? Do Now 1.Find your Vision Sensation fill-in-theblanks
More informationThe Human Eye and a Camera 12.1
The Human Eye and a Camera 12.1 The human eye is an amazing optical device that allows us to see objects near and far, in bright light and dim light. Although the details of how we see are complex, the
More informationSCIENCE 8 WORKBOOK Chapter 6 Human Vision Ms. Jamieson 2018 This workbook belongs to:
SCIENCE 8 WORKBOOK Chapter 6 Human Vision Ms. Jamieson 2018 This workbook belongs to: Eric Hamber Secondary 5025 Willow Street Vancouver, BC Table of Contents A. Chapter 6.1 Parts of the eye.. Parts of
More informationPhysiology of Vision The Eye as a Sense Organ. Rodolfo T. Rafael,M.D. Topics
Physiology of Vision The Eye as a Sense Organ Rodolfo T. Rafael,M.D. www.clinicacayanga.dailyhealthupdates.com 1 Topics Perception of Light Perception of Color Visual Fields Perception of Movements of
More informationZoology. Lesson: Physiology of Vision. Lesson Developer: Dr. Mahtab Zarin. College/Dept: Zoology, University of Delhi
Zoology Lesson: Physiology of Vision Lesson Developer: Dr. Mahtab Zarin College/Dept: Zoology, University of Delhi Institute of Life Long Learning, University of Delhi 1 Table of Contents Introduction
More informationThe Physiology of the Senses Lecture 1 - The Eye
The Physiology of the Senses Lecture 1 - The Eye www.tutis.ca/senses/ Contents Objectives... 2 Introduction... 2 Accommodation... 3 The Iris... 4 The Cells in the Retina... 5 Receptive Fields... 8 The
More informationVision Science I Exam 1 23 September ) The plot to the right shows the spectrum of a light source. Which of the following sources is this
Vision Science I Exam 1 23 September 2016 1) The plot to the right shows the spectrum of a light source. Which of the following sources is this spectrum most likely to be taken from? A) The direct sunlight
More informationSpatial Vision: Primary Visual Cortex (Chapter 3, part 1)
Spatial Vision: Primary Visual Cortex (Chapter 3, part 1) Lecture 6 Jonathan Pillow Sensation & Perception (PSY 345 / NEU 325) Princeton University, Fall 2017 Eye growth regulation KL Schmid, CF Wildsoet
More informationThe Human Brain and Senses: Memory
The Human Brain and Senses: Memory Methods of Learning Learning - There are several types of memory, and each is processed in a different part of the brain. Remembering Mirror Writing Today we will be.
More informationSCIENCE 8 WORKBOOK Chapter 6 Human Vision Ms. Jamieson 2018 This workbook belongs to:
SCIENCE 8 WORKBOOK Chapter 6 Human Vision Ms. Jamieson 2018 This workbook belongs to: Eric Hamber Secondary 5025 Willow Street Vancouver, BC Table of Contents A. Chapter 6.1 Parts of the eye.. Parts of
More informationLife Science Chapter 2 Study Guide
Key concepts and definitions Waves and the Electromagnetic Spectrum Wave Energy Medium Mechanical waves Amplitude Wavelength Frequency Speed Properties of Waves (pages 40-41) Trough Crest Hertz Electromagnetic
More informationChapter 22: Illumination and Vision
Chapter 22: Illumination and Vision Learning Outcomes After successful studying this chapter, You should be able to Explain how we see objects? Discus the anatomical structure of the eye, Describe the
More informationEYE: THE PHOTORECEPTOR SYSTEM. Prof. Dr. Huda Al Khateeb
EYE: THE PHOTORECEPTOR SYSTEM Prof. Dr. Huda Al Khateeb Lecture 1 The eye ball Objectives By the end of this lecture the student should: 1. List the layers and chambers of the eye ball 2. Describe the
More informationExam 3--PHYS 151--S15
Name: Class: Date: Exam 3--PHYS 151--S15 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Consider this diagram of the eye and answer the following questions.
More informationVISUAL SYSTEM PHYSIOLOGY. Discipline of Physiology and Neuroscience, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
VISUAL SYSTEM PHYSIOLOGY Discipline of Physiology and Neuroscience, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania Outer layer of the eye Cornea - No bood vessels - Most powerful
More informationYokohama City University lecture INTRODUCTION TO HUMAN VISION Presentation notes 7/10/14
Yokohama City University lecture INTRODUCTION TO HUMAN VISION Presentation notes 7/10/14 1. INTRODUCTION TO HUMAN VISION Self introduction Dr. Salmon Northeastern State University, Oklahoma. USA Teach
More informationSheep Eye Dissection
Sheep Eye Dissection Question: How do the various parts of the eye function together to make an image appear on the retina? Materials and Equipment: Preserved sheep eye Scissors Dissection tray Tweezers
More informationLectures on Medical Biophysics Department of Biophysics, Medical Faculty, Masaryk University, Brno. Biophysics of visual perception
Lectures on Medical Biophysics Department of Biophysics, Medical Faculty, Masaryk University, Brno 1 Lecture outline Basic properties of light Anatomy of eye Optical properties of eye Retina biological
More informationChapter Human Vision
Chapter 6 6.1 Human Vision How Light Enters the Eye Light enters the eye through the pupil. The pupil appears dark because light passes through it without reflecting back Pupil Iris = Coloured circle of
More informationVision. PSYCHOLOGY (8th Edition, in Modules) David Myers. Module 13. Vision. Vision
PSYCHOLOGY (8th Edition, in Modules) David Myers PowerPoint Slides Aneeq Ahmad Henderson State University Worth Publishers, 2007 1 Vision Module 13 2 Vision Vision The Stimulus Input: Light Energy The
More informationVision. Definition. Sensing of objects by the light reflected off the objects into our eyes
Vision Vision Definition Sensing of objects by the light reflected off the objects into our eyes Only occurs when there is the interaction of the eyes and the brain (Perception) What is light? Visible
More informationSeeing and Perception. External features of the Eye
Seeing and Perception Deceives the Eye This is Madness D R Campbell School of Computing University of Paisley 1 External features of the Eye The circular opening of the iris muscles forms the pupil, which
More informationMaterials Cow eye, dissecting pan, dissecting kit, safety glasses, lab apron, and gloves
Cow Eye Dissection Guide Introduction How do we see? The eye processes the light through photoreceptors located in the eye that send signals to the brain and tells us what we are seeing. There are two
More informationensory System III Eye Reflexes
ensory System III Eye Reflexes Quick Review from Last Week Eye Anatomy Inside of the Eye choroid Eye Reflexes Eye Reflexes A healthy person has a number of eye reflexes: Pupillary light reflex Vestibulo-ocular
More informationVision. Sensation & Perception. Functional Organization of the Eye. Functional Organization of the Eye. Functional Organization of the Eye
Vision Sensation & Perception Part 3 - Vision Visible light is the form of electromagnetic radiation our eyes are designed to detect. However, this is only a narrow band of the range of energy at different
More informationThis question addresses OPTICAL factors in image formation, not issues involving retinal or other brain structures.
Bonds 1. Cite three practical challenges in forming a clear image on the retina and describe briefly how each is met by the biological structure of the eye. Note that by challenges I do not refer to optical
More informationSense Organs (Eye) The eye is the sense organ of sight. The eye is shaped like a ball and is located in bony
Sense Organs (Eye) The eye is the sense organ of sight. The eye is shaped like a ball and is located in bony sockets in the skull. It is held in place by six muscles which are joined to the outside of
More informationHSC Biology. Published Feb 9, 2017 HSC BIOLOGY OPTION: COMMUNICATION. By Sahar (99.1 ATAR)
HSC Biology Year 2014 Mark 92.00 Pages 11 Published Feb 9, 2017 HSC BIOLOGY OPTION: COMMUNICATION By Sahar (99.1 ATAR) Your notes author, Sahar. Sahar achieved an ATAR of 99.1 in 2014 while attending Carlingford
More informationIntroduction. Chapter Aim of the Thesis
Chapter 1 Introduction 1.1 Aim of the Thesis The main aim of this investigation was to develop a new instrument for measurement of light reflected from the retina in a living human eye. At the start of
More informationOcular Jeopardy. The major refractive portion of the eye 5/12/2015. Presented by Jill J Luebbert, CPOT, ABOC. Watch This Refractive optios
Ocular Jeopardy Presented by Jill J Luebbert, CPOT, ABOC In the beginning anterior Way back Visual Pathway Say What? terminolog y Watch This Refractive optios Posterior Segment 10 10 10 10 10 20 20 20
More informationAS Psychology Activity 4
AS Psychology Activity 4 Anatomy of The Eye Light enters the eye and is brought into focus by the cornea and the lens. The fovea is the focal point it is a small depression in the retina, at the back of
More informationThe Hyman Eye and the Colourful World
The Hyman Eye and the Colourful World In this chapter we will study Human eye that uses the light and enable us to see the objects. We will also use the idea of refraction of light in some optical phenomena
More informationChapter 25: Applied Optics. PHY2054: Chapter 25
Chapter 25: Applied Optics PHY2054: Chapter 25 1 Operation of the Eye 24 mm PHY2054: Chapter 25 2 Essential parts of the eye Cornea transparent outer structure Pupil opening for light Lens partially focuses
More informationClass 10 Science NCERT Exemplar Solutions Human Eye and Colourful World
Class 10 Science NCERT Exemplar Solutions Human Eye and Colourful World Short Answer Questions Question 1. A student sitting at the back of the classroom cannot read clearly the letters written on the
More informationFurther reading. 1. Visual perception. Restricting the light. Forming an image. Angel, section 1.4
Further reading Angel, section 1.4 Glassner, Principles of Digital mage Synthesis, sections 1.1-1.6. 1. Visual perception Spencer, Shirley, Zimmerman, and Greenberg. Physically-based glare effects for
More informationCHAPTER 11 The Hyman Eye and the Colourful World In this chapter we will study Human eye that uses the light and enable us to see the objects. We will also use the idea of refraction of light in some optical
More informationLecture Outline. Basic Definitions
Lecture Outline Sensation & Perception The Basics of Sensory Processing Eight Senses Bottom-Up and Top-Down Processing 1 Basic Definitions Sensation: stimulation of sense organs by sensory input Transduction:
More informationPhotography (cont d)
Lecture 13 Ch. 4 Photography continued Ch. 5 The Eye Feb. 23, 2010 Exams will be back on Feb. 25 Homework 5 is due Feb. 25 Read all of Ch. 5. on The Eye. 1 Photography (cont d) Polarizing and haze filters
More informationVisual Perception of Images
Visual Perception of Images A processed image is usually intended to be viewed by a human observer. An understanding of how humans perceive visual stimuli the human visual system (HVS) is crucial to the
More information1. What are the components of your nervous system? 2. How do telescopes and human eyes work?
Chapter 18 Vision and Hearing Although small, your eyes and ears are amazingly important and complex organs. Do you know how your eyes and ears work? Scientists have learned enough about these organs to
More informationA&P 1 Eye & Vision Lab Vision Concepts
A&P 1 Eye & Vision Lab Vision Concepts In this "Lab Exercise Guide", we will be looking at the basics of vision. NOTE: these notes do not follow the order of the videos. You should be able to read this
More informationPsych 333, Winter 2008, Instructor Boynton, Exam 1
Name: Class: Date: Psych 333, Winter 2008, Instructor Boynton, Exam 1 Multiple Choice There are 35 multiple choice questions worth one point each. Identify the letter of the choice that best completes
More information12.1. Human Perception of Light. Perceiving Light
12.1 Human Perception of Light Here is a summary of what you will learn in this section: Focussing of light in your eye is accomplished by the cornea, the lens, and the fluids contained in your eye. Light
More informationbetter make it a triple (3 x)
Crown 85: Visual Perception: : Structure of and Information Processing in the Retina 1 lectures 5 better make it a triple (3 x) 1 blind spot demonstration (close left eye) blind spot 2 temporal right eye
More informationLab #8: The Special Senses: Hearing, Vision, and Orientation
Lab #8: The Special Senses: Hearing, Vision, and Orientation Background The special senses (vision, hearing, equilibrium, gustation, and olfaction) differ from the somatesthetic senses in two fundamental
More informationWhat determines data speed?
PHY385-H1F Introductory Optics Class 12 Outline: Section 5.7, Sub-sections 5.7.1 5.7.6 Fibre-Optics The Human Eye Corrective Lenses Pinhole Camera Camera Depth of Field What determines data speed? Broadband
More informationPHYSICS. Chapter 35 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT
PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 35 Lecture RANDALL D. KNIGHT Chapter 35 Optical Instruments IN THIS CHAPTER, you will learn about some common optical instruments and
More information11 Human Eye & colourful world IMPORTANT NOTES ANIL TUTORIALS
11 Human Eye & colourful world IMPORTANT NOTES 1. Parts of the Human Eye : (i) Sclerotic is the outermost white fibrous covering of the eye. (ii) Cornea is the transparent front bulging portion of the
More informationSensation. Our sensory and perceptual processes work together to help us sort out complext processes
Sensation Our sensory and perceptual processes work together to help us sort out complext processes Sensation Bottom-Up Processing analysis that begins with the sense receptors and works up to the brain
More information