Vision and visual pathway

Question

Vision - choose correct

Answer 1

Electromagnetic radiation in this range of wavelengths is called visible light or simply light.

Answer 2

The optical spectrum is the portion of the electromagnetic spectrum that is visible to the animal eye.

Answer 3

The visible spectrum is approximately between 400nm to 750nm

Answer 4

8% of men are colour blind, it's a Y-linked disease

Answer 5

Both photoreceptors are found in the inner nuclear layer of the retina at the back of each eye

Answer 6

Bipolar and ganglion cells send information from photoreceptors to the brain are in front of the cones and rods

Answer 7

The human eye have 6 million cones and 120 million rods

Answer 8

Cones and rods are types neurons

Answer 9

Albinos don't have colour vision

Answer 10

Albinos have reduced pigment epithelium in sclera and choroid

Answer 11

Albinos have colour vision

Answer 12

Albinos have increased visual acuity, due to intra-ocular reflection of light

Answer 13

Retinal ganglion cells that express the photopigment melanopsin.

Answer 14

In the absence of rods and cones, mammals retain the ability to detect light for various non-image-forming visual functions.

Answer 15

Phototransduction is conducted only by cones and rods

Answer 16

Cones have rhodopsin and rods have fotopsin

Answer 17

Photosensitive ganglion cells seem to serve as photoreceptors for the photic synchronization of circadian rhythms.

Answer 18

Cones innervate the midbrain pupillary control center.

Answer 19

They project to the circadian pacemaker of the brain - the suprachiasmatic hypothalamic nucleus

Answer 20

Photosensitive ganglion cells contribute to the pupillary light reflex and other behavioral and physiological responses to environmental

Answer 21

Rods/cones - Glutamate

Answer 22

Amacrine cells - Inhibitory neurotransmitters (GABA, Glycine, Dopamine, Ach, Indolamine)

Answer 23

Horizontal cells - Excitatory neurotransmitters.

Answer 24

Horizontal cells - Inhibitory neurotransmitters.

Answer 25

Ganglion cells - the only retinal cell of the pathway transmitting signals by mean of action potential.

Answer 26

Amacrine cells - Occasionally action potential is recorded in.

Answer 27

Remaining cells of the retina - conduct their visual signals by electrotonic conduction (graded conduction).

Answer 28

Ganglion cells - conduct their visual signals by electrotonic conduction (graded conduction).

Answer 29

Rods are used to determine color, depth, and intensity.

Answer 30

Each particular photosensitive cell responds to monochromatic spectral stimuli

Answer 31

All 3 types of photoreceptors transduce light into a change in membrane potential through different signal transduction pathway.

Answer 32

All 3 types of photoreceptors differ in the nature of the opsin they contain and therefore in their function.

Answer 33

Cones are divided into red, blue and green

Answer 34

Visual imaging occurs in the visual cortex, occipital lobe

Answer 35

Fovea has the lowest visual acuity

Answer 36

Rods are trichromatic

Answer 37

Dark current - the voltage-gated sodium channels in the outer segment are opened due to cGMP bound to them.

Answer 38

Dark current - depolarising sodium channels to - 40mV, in dark conditions

Answer 39

Rods are also de-polarising in light conditions

Answer 40

Cones de-polarise in dark conditions

Answer 41

The opsin in the outer segment absorbs a photon, changing the configuration of a molecule inside the cell from the less- energetic cis-form to the more-energetic trans-form.

Answer 42

Night blindness can be caused by deficiency of vitamin E

Answer 43

The light acts as a ligand

Answer 44

Light is absorbed by rhodopsin or by one of the photopsins of cones, changing shape of the retina.

Answer 45

Each photo-activated rhodopsin triggers activation of about 100 transducins

Answer 46

PDE inhibits the hydrolysis of cGMP

Answer 47

Each transducin then activates the enzyme cGMP-specific phosphodiesterase (PDE)

Answer 48

cGMP was keeping the Na(Ca channels closed

Answer 49

A photoreceptor actually releases less neurotransmitter when stimulated by light.

Answer 50

Hyper-polarization means that less glutamate is released to the bipolar cell than before.

Answer 51

GTP provided by the inner segment powers the sodium- potassium pump.

Answer 52

The opening of Na+ channels hyperpolarizes the cell

Answer 53

Neurons of layer 4 of the visual cortex (Brodman’s area 17).

Answer 54

Bipolar cells, Photosensitive cells and Ganglion cells.

Answer 55

Horizontal and amacrine cells

Answer 56

Cells of the lateral geniculate body of the thalamus.

Answer 57

Old system - Suprachasmatic nucleus of hypothalamus – SCN (circadian rhythms)

Answer 58

Old System - Lateral geniculate nucleus of thalamus (LGN)

Answer 59

Old system - Visual cortex (4th neuronal of Brodman’s field 17)

Answer 60

Old system - Pretectal nuclei of the midbrain (pupillary reflexes) & Superior colliculi (rapid eye movement of both eyes)

Answer 61

Parvocellular portion of LGN - (shape, color, texture, fine detail).

Answer 62

Interlaminar path - conduct impulses from ipsilateral eye.

Answer 63

Magnocellular portion of LGN - (spatial organisation, movement, location)

Answer 64

Layers 1,4,6 - colour

Answer 65

Right retina - Left hemisphere, calcarine fissure

Answer 66

Left retina - Right hemisphere, cuneus gyrus fissure

Answer 67

Temporal vision crosses at the optic chiasm

Answer 68

Nasal vision crosses at the optic chiasm

Answer 69

V2, V3, VP – Motion, control of movement.

Answer 70

V3A , MT/V5 – Continued processing – larger visual field.

Answer 71

V1 – Primary visual cortex – receives input from the LGN – processing in terms on orientation edges, etc.

Answer 72

LO – Recognition of large objects.

Answer 73

V8 – Color vision.

Answer 74

Light, passing from one transparent medium to another, changes its speed, and bends.

Answer 75

Angle of refraction - The angle between the light ray and the normal, as it leaves a medium.

Answer 76

Each medium has its own refractive index

Answer 77

Angle of incidence - The angle between the light ray and the normal as it enters a medium

Answer 78

Strength of the light ray

Answer 79

The angle between the light ray and the line perpendicular to the surface separating both media

Answer 80

The refractive index of the media

Answer 81

Absence of other sources of light

Answer 82

Parallel light rays are bent to pass through a single point behind the lens (focal point)

Answer 83

Rays striking perpendicular lens surface pass the lens by bending

Answer 84

Convex lenses diverge light rays

Answer 85

Rays striking perpendicular lens surface pass the lens without being bent

Answer 86

In the focal length distant sources of light rays are parallell

Answer 87

In the focal length distant sources of light rays are converged

Answer 88

In the focal length the close source is parallell

Answer 89

Focal length - distance beyond midpoint of a convex lens, and the focal point

Answer 90

Reversed - Upside-down, left side-right

Answer 91

Inversed - Downside-up, left side-right

Answer 92

Each point source of light on the object comes to a separate point focus on the opposite side of the lens in line with the lens centre

Answer 93

Only one source of light on the object comes to a separate point focus on the opposite side of the lens in line with the lens centre

Answer 94

Expressed in diopters

Answer 95

Spherical Convex lenses = -1 power

Answer 96

Spherical Concave lenses = +1 power

Answer 97

Spherical Convex lenses = + 10 power

Answer 98

Interface between posterior surface of the cornea and aqueous humour is a part of the optic system

Answer 99

Interface on both sides of the lens are parts of the optic system

Answer 100

Interface between the retina and the optic nerve is a part of the optic system

Answer 101

Interface between air and the anterior surface of the cornea is a part of the optic system

Answer 102

The lens = 1.40

Answer 103

The cornea = 1.33

Answer 104

The aqueous humour = 1.38

Answer 105

The vitreous humour = 1.34

Answer 106

1/3 of all the refractive power of the eye is provided by the anterior surface of the cornea.

Answer 107

Total refractive power of the eye is 59 dioptres

Answer 108

2/3 of all the refractive power of the eye is provided by the anterior surface of the cornea.

Answer 109

Total refractive power of the eye is 39 dioptres

Answer 110

Reduced eye - a simplified design of the ocular optical system, represented as having a single refracting surface and a uniform index of refraction

Answer 111

Reduced eye - By close object the light rays are diverged and refraction power of the eye should be increased in order to focus eye on object and produce the image exactly on the retina.

Answer 112

Accommodation - By close object the light rays are diverged and refraction power of the eye should be increased in order to focus eye on object and produce the image exactly on the retina.

Answer 113

Accommodation - a simplified design of the ocular optical system, represented as having a single refracting surface and a uniform index of refraction

Answer 114

Refraction power of the eye can be increased voluntary by approximately 14 dioptres by changing the shape of the lens from moderately convexed to more convexed.

Answer 115

In normal conditions tension of ligaments of the lens causes its to remain spherically shaped.

Answer 116

Contraction of the ciliary muscle depend on parasympathetic transmission via III CN.

Answer 117

Contraction of smooth muscle fibers in the ciliary muscle tenses the ligaments to the lens capsule and the lens assumes a more spherical shape.

Answer 118

Reduced eye – refraction power 59 D

Answer 119

With age gets farther away

Answer 120

Light rays are divergent

Answer 121

Picks up 6 m and more distant objects.

Answer 122

Parallell light rays, and the point of vision comes closer with age

Answer 123

About 20 cm in front of eyes

Answer 124

Does not require accommodation

Answer 125

The nearest point in front of eye which can be focused on retina

Answer 126

Accomodation

Answer 127

Pupillary constriction

Answer 128

Pupillary dilation

Answer 129

Divergence of the visual axes

Answer 130

Distant object - parallel light rays focuses on retina

Answer 131

Light rays focus behind the retina

Answer 132

Close object - contraction of ciliary muscle provide accommodation – diverge rays are focus on retina

Answer 133

Light rays focus in front of the retina

Answer 134

Presbypia (senile farsightedness) is caused by decreased lens elasticity

Answer 135

Presbypia (senile farsightedness) is caused by decreased power of ciliary muscle

Answer 136

Astigmatism is caused by a cornea that isn't spherical

Answer 137

Astigmatism is corrected with concave lenses

Answer 138

Fixation of eye (fovea centralis)

Answer 139

Refraction index of medium

Answer 140

Astigmatism

Answer 141

Optical factors (image-forming mechanisms of the eye)

Answer 142

Depth of vision

Answer 143

Retinal factors

Answer 144

Stimulus factors (illumination, brightness, contrast, time of exposure)

Answer 145

Distance is perceived by - sizes of known objects, moving parallax and stereopsis

Answer 146

Distance is perceived by - sizes of unknown objects and stereopsis

Answer 147

Distance is perceived by - relative distance, fast moving close objects and slow moving far objects

Answer 148

Stereopsis is dependent on mono-ocular vision - image only created on retina

Answer 149

Rhodopsin decompose in darkness

Answer 150

Rhodopsin is combined of scotopsin and retinene-1 (aldehyde of vit. A)

Answer 151

The only retinal neurons that transmit visual signal by means of action potential are the ganglia cells

Answer 152

Activated rhodopsin deactivates transducin

Answer 153

Photon activates an electron

Answer 154

Activated transducin activates rhodopsin

Answer 155

Activated transducin activates cGMP

Answer 156

Phosphodiesterase hydrolyzes cGMP (which normally causes Na-channels stay open), and Na-channels close

Answer 157

Found 15 degrees temporally to visual axis

Answer 158

It is NOT visible through the ophtalmoscope as the optic disc.

Answer 159

The optic nerve leaves the eye at the point 3 mm medial to and slightly above the posterior pole of the globe

Answer 160

There are some photoreceptors in this area

Answer 161

Optic N. (CN2) - Mediates vision

Answer 162

Oculomotor N. (CN3) - innervates superior oblique muscle

Answer 163

Trochlear N. (CN4) - innervates superior oblique muscle

Answer 164

Trigeminal N. (CN5) - sensory portion of corneal reflex

Answer 165

Abducens N. (CN6) - Innervates orbicularis oculi and lacrimal glands

Answer 166

Light adaptation (photopic vision) - regeneration of photopigment, that in turn increases visual sensitivity

Answer 167

Dark adaptation (scotopic vision) - a reduction in the amount of rhodopsin, which in turn reduces visual sensitivity

Answer 168

Light adaptation time is 5min

Answer 169

Dark adaptation time is 20min

Answer 170

Laterally = 90 degrees

Answer 171

Downward = 50 degrees

Answer 172

Upward = 50 degrees

Answer 173

Medially 65-70 degrees

Answer 174

1, 3, 2, 4, 5

Answer 175

4, 2, 5, 1, 3

Answer 176

2, 4, 5, 1, 3

Answer 177

4, 5, 2, 1, 3

Answer 178

Axons of ganglia cells converge and leave eye as the optic nerve through optic disc.

Answer 179

The temporal optic fibers cross at the optic chiasm

Answer 180

Each optic tract fibres synapse in ventral lateral geniculate nucleus of lateral geniculate body (LGB) of the thalamus.

Answer 181

Geniculocalcarine fibres pass as optic radiation to the primary visual cortex in the calcarine fissure area of the medial occipital lobe (striate cortex)

Answer 182

Geniculate body has 6 layers, 2 main parts parvocellular and magnocellular

Answer 183

Parvocellular -carries signals for colour vision, texture, shape, fine detail

Answer 184

Parvocellular - carries signals for detection of movement, depth and flicker

Answer 185

Major input comes form the retina

Answer 186

Primary cortex; Brodmann’s area 18 (V2),19

Answer 187

Secondary cortex; Brodmann’s area 17 ( also known as V1)

Answer 188

Area V8 concern with colour vision

Answer 189

Dorsal and parietal pathway – motion

Answer 190

Ventral and temporal pathway – shape and recognition of forms and faces

Answer 191

Optic chiasm – right or left homonymus hemianopia (half-blindness in same side half of the visual field

Answer 192

Interruption of optic nerve – blindness in the eye

Answer 193

Occipital lesion – macular sparing (loss of peripheral vision with intact macular vision)

Answer 194

Optic tract - bitemporal heteronymous hemianopia (half-blindness in opposite sides of the visual field)

Answer 195

Afferent pathway: photoreceptors, bipolar cells, ganglion cells, optic nerve, optic tract, nuleus pretectalis and farther to Edinger-Westphal nucleus bilaterally.

Answer 196

Efferent pathway: from Edinger-Westphal nucleus through oculomotor nerve to ciliary ganglion and n.n. ciliares breves to papillary sphincter.

Answer 197

Efferent pathway: photoreceptors, bipolar cells, ganglion cells, optic nerve, optic tract, nuleus pretectalis and farther to Edinger-Westphal nucleus bilaterally.

Answer 198

Afferent pathway: from Edinger-Westphal nucleus through oculomotor nerve to ciliary ganglion and n.n. ciliares breves to papillary sphincter.

Answer 199

Slit lamp - facilitates examination of the eyelid, sclera, conjunctiva, iris, natural crystalline lens, and cornea

Answer 200

Ophtalmoscopy - Used to determine the health of retina and the vitreous humour

Answer 201

Ophtalmoscopy - facilitates examination of the eyelid, sclera, conjunctiva, iris, natural crystalline lens, and cornea

Answer 202

Perimetry - maps and quantifies the visual field

Answer 203

Slit lamp - maps and quantifies the visual field

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Vision and visual pathway

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