Task 8 - The visual system

Question 1

Lens

Answer 1

helps focus an image on the retina

Question 2

pupil

Answer 2

allows light to enter the eye - contracts and dilate

Question 3

iris

Answer 3

provides and opening to form the pupil

Question 4

cornea

Answer 4

outer layer of the eye - bends light rays and is primarily responsable for forming the image of the retina

Question 5

sclera

Answer 5

supports wall of the eyeball

Question 6

optic nerve

Answer 6

collection of ganglion cells axons that extend from the retina to the optic chiasm

Question 7

retina

Answer 7

receptive surface inside the eye (photoreceptors)

Question 8

macula

Answer 8

sensitive area of the retina that gives central vision

Question 9

ciliary muscle

Answer 9

controls shape of the lens - focusing image on the retina

Question 10

vitreous gel

Answer 10

transparent gel that fills two thirds of the eyeball between the lens and the retina

Question 11

choroid

Answer 11

provides blood supply

Question 12

wavelength (organization of the retina)

Answer 12

length between two peaks in a repeated stimulus such a wave, light and sound

Question 13

photon (organization of the retina)

Answer 13

electromagnetic energy - light

Question 14

refraction (organization of the retina)

Answer 14

bending of light rays by a change in density of a medium

Question 15

accommodation (organization of the retina)

Answer 15

process of focusing

Question 16

extraocular muscle (organization of the retina)

Answer 16

muscle attached to the eyeball that controls its position and movement

Question 17

photoreceptors (organization of the retina)

Answer 17

respond to light

Question 18

rods (organization of the retina)

Answer 18

light sensitive receptor - most active at low levels of light

Question 19

cones (organization of the retina)

Answer 19

photoreceptor - responsable for color vision - high levels of light

Question 20

bipolar cells (organization of the retina)

Answer 20

interneurons of the retina - receives information from rods and cones and passes it to retinal ganglion cells

Question 21

ganglion cells (organization of the retina)

Answer 21

axons form the optic nerve

Question 22

horizontal cells (organization of the retina)

Answer 22

retinal neurons that contact both bipolar cells and the ganglion cells - significant in inhibitory interactions within the retina

Question 23

fovea (organization of the retina)

Answer 23

packed with the most photoreceptors - center of our gaze

Question 24

blind spot

Answer 24

visual field form which light falls on the optic disc - no receptors in this region light striking it cant be seen

Question 25

How does light get converted into neurological signal

Answer 25

When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images

Question 26

Visual field

Answer 26

the whole area you can see without moving

Question 27

neural signals travel from the retina to brain regions (7)

Answer 27

1. ganglion cells on each eye produce action potentials that conducted along their axons to send visual information to the brain
2. axon makes up the optic nerve that bring information on each side
3. primary visual cortex passes along the info to other visual cortical regions
4. axons of each optic nerve travel to the opposite hemisphere of the brain
5. optic nerves cross the midline at the optic chiasm
6. after the optic nerves pass the optic chiasm the retinal ganglion cells are known collectively as the optic track
7. optic tract - terminate on cells in the visual position of the thalamus

Question 28

what lifestyle factor contribute to eye development

Answer 28

• socioeconomically disadvantaged families became more myopic
• myopia is triggered by changing lifestyle in childhood
• play outdoors is beneficial - decreases use of computers
• genetic factors