> is the sensory organ used for vision > detect light and send signals to the brain, which then interprets these signals to create the visual experience.

> THE CLEAR, DOME-SHAPED SURFACE THAT COVERS THE FRONT OF THE EYE. IT IS RESPONSIBLE FOR REFRACTING LIGHT AND PLAYS A CRUCIAL ROLE IN FOCUSING LIGHT RAYS ONTO THE RETINA

> THE COLORED PART OF THE EYE THAT CONTROLS > THE SIZE OF THE PUPIL, THUS REGULATING THE AMOUNT OF LIGHT THAT ENTERS THE EYE

> THE OPENING IN THE CENTER OF THE IRIS, WHICH GIVES OUR EYES THEIR COLOR. > ITS PRIMARY FUNCTION IS TO ALLOW LIGHT TO ENTER THE EYE SO IT CAN BE FOCUSED ON THE RETINA TO BEGIN THE PROCESS OF SIGHT

> THE TOUGH, WHITE OUTER LAYER OF THE EYEBALL, PROVIDING IT WITH STRUCTURAL SUPPORT AND PROTECTION

> TRANSPARENT STRUCTURE SITUATED BEHIND THE PUPIL. > IT FOCUSES LIGHT ONTO THE RETINA AND PLAYS A KEY ROLE IN ADJUSTING THE EYE'S FOCUS

> LIGHT-SENSITIVE LAYER THAT LINES THE INTERIOR OF THE EYE. > IT CONTAINS PHOTORECEPTOR CELLS CALLED RODS AND CONES, WHICH CONVERT LIGHT INTO NEURAL SIGNALS

THE RETINA CONSISTS OF THREE LAYERS OF CELLS > RECEPTORS IN THIS LAYER TRANSDUCE LIGHT

> ARE SPECIALIZED CELLS THAT DETECT LIGHT AND CONVERT IT INTO ELECTRICAL SIGNALS. > THERE ARE TWO TYPES: RODS AND CONES

> ARE RESPONSIBLE FOR VISION IN LOW LIGHT CONDITIONS

> ARE RESPONSIBLE FOR COLOR VISION AND VISUAL ACUITY

> 120 MILLION > LIGHT SENSITIVE (NOT COLOR) > FOUND IN PERIPHERY OF RETINA > LOW ACTIVATION THRESHOLD

> 6 MILLION > ARE COLOR SENSITIVE > FOUND MOSTLY IN FOVEA

THE ___________ OF A ROD OR A CONE CONTAINS DIFFERENT PHOTOPIGMENTS THAT REACT TO LIGHT

> occurs when there is plenty of light > cones are responsible

> dim light > rods are responsible

> hundreds per ganglion cell > can amplify a dim light source > high sensitivity, low aquity

> as few as one per ganglion cell > low sensitivity, high aquity

> ARE LOCATED IN THE MEMBRANE OF THE OUTER SEGMENT OF RODS AND CONES

opsin

retinal

> ARE RESPONSIBLE FOR NIGHT VISION. > THEY DETECT CHANGES IN LIGHT INTENSITY AND SIGNAL THE BRAIN TO ADJUST THE PUPIL SIZE AND SENSITIVITY TO LIGHT

> ARE RESPONSIBLE FOR COLOR VISION. > THERE ARE THREE TYPES OF THESE OPSINS IN HUMANS: SHORT-WAVELENGTH, MIDDLE-WAVELENGTH, AND LONG-WAVELENGTH OPSINS * EACH RESPONSIBLE FOR DETECTING A SPECIFIC RANGE OF LIGHT WAVELENGTHS

> IS A LIGHT-SENSITIVE MOLECULE THAT BINDS TO OPSINS. > WHEN BOUND TO OPSINS, ______ UNDERGOES A SERIES OF CHEMICAL REACTIONS THAT ALLOW THE OPSINS TO DETECT LIGHT AND TRANSMIT SIGNALS TO THE BRAIN

> IN THE DARK, MEMBRANE NA+ CHANNELS ARE OPEN >GLUTAMATE IS RELEASED

> LIGHT SPLITS THE OPSIN AND RETINAL APART >ACTIVATES TRANSDUCIN (G PROTEIN)-> > ACTIVATES PHOSPHODIESTERASE-> >REDUCES CGMP -> CLOSES NA+ CHANNELS

> ARE RESPONSIBLE FOR INTEGRATING AND MODULATING THE SIGNALS RECEIVED FROM THE PHOTORECEPTORS, THUS CONTRIBUTING TO THE INITIAL PROCESSING OF VISUAL INFORMATION WITHIN THE RETINA

> RECEIVE INPUT FROM THE BIPOLAR CELLS AND TRANSMIT IT TO THE BRAIN VIA THE OPTIC NERVE. > THERE ARE TWO TYPES:ON&OFF * ON ARE EXCITED BY LIGHT * OFF ARE INHIBITED BY LIGHT

SIGNALS FROM THE GANGLION CELLS OF THE RETINA ARE SENT TO THE _______ VIA THE OPTIC NERVE/TRACT

> IS A SMALL, HIGHLY SPECIALIZED AREA OF THE RETINA THAT IS RESPONSIBLE FOR OUR CENTRAL VISION > PROVIDES THE SHARPEST VISUAL ACUITY NEEDED FOR DETAILED TASKS LIKE READING AND DISTINGUISHING BETWEEN DIFFERENT COLORS.

> DENSELY PACKED WITH PHOTORECEPTORS, PARTICULARLY CONES, WHICH ARE RESPONSIBLE FOR COLOR VISION. > IT IS OFTEN COMPARED TO THE BULLSEYE ON A DARTBOARD, EMPHASIZING ITS CRITICAL ROLE IN OUR ABILITY TO SEE FIN E DETAILS AND PERCEIVE COLOR.

THE NERVE THAT TRANSMITS VISUAL INFORMATION FROM THE RETINA TO THE BRAIN FOR FURTHER PROCESSING

> neurons have smaller cellular bodies > respond to color, fine details, still objects, slow moving objects

interprets spatial information (location/motion)

interprets object characteristics (color/shape)

> ARE SPECIALIZED NERVE CELLS THAT TRANSDUCE ENERGY INTO NEURAL SIGNALS

THE FUNCTION OF A ________ IS TO DETECT ELECTROMAGNETIC RADIATION (EMR) EMITTED BY OBJECTS

HUMANS CAN DETECT LIGHT WITH A WAVELENGTH BETWEEN

IS RELATED TO THE WAVELENGTH OF LIGHT BRIGHTNESS IS RELATED TO THE INTENSITY OF THE RADIATION

> first scientific theory of color vision > proposed by Hermann von Helmholtz > three types of cones sensitive to diff. wavelengths of light

> PROPOSES THAT ONE MEMBER OF THE COLOR PAIR SUPPRESSES THE OTHER COLOR. > PROPOSED BY GERMAN PHYSIOLOGIST EWALD HERING IN THE LATE 1800S.

> organizing and interpreting visual signals

form or whole in German

> people organize sensations into meaningful whole > perceptions are naturally organized according to certain patterns

organization of visual field into objects that stand out from their surroundings

the perpetual tendency to organize stimuli into meaningful groups

> ability to see objects in 3D > although images that strike the retina are 2D > allows people to judge distance

happens when visual stimulis are presented at different locations in a sequential manner

gaps of myelin sheath

fastening of action potential

> is responsible for transmitting visual information from the optic nerves to the occipital lobes of the brain