Sensory Systems

Question 1

What visible light colour has the highest frequency? Lowest?

Answer 1

blue, red

Question 2

How much info about our environment comes from our eyes?

Answer 2

up to 70%

Question 3

What converts light energy to biological information?

Answer 3

photoreceptors

Question 4

Where do eyes first develop evolutionarily?

Answer 4

jellyfish

Question 5

Do microbes have eyes?

Answer 5

no, but they can sense light

Question 6

What are the different eye types?

Answer 6

simple lens eye, simple corneal eye, compound eye

Question 7

What is a simple lens eye? What are some examples of things with these eyes?

Answer 7

single chamber with retina on one side and lens on the other

vertebrates, squid/octopus, jellyfish

Question 8

What is a simple corneal eye? What is an example of things with these eyes?

Answer 8

no lens, light is focused only by cornea onto retina

arachnids

Question 9

What is a compound eye? What are some examples of things with these eyes?

Answer 9

consists of many identical visual units each with own lens and receptor (like a bunch of mini eyes looking in diff directions)

insects, crustaceans

Question 10

What is the cornea?

Answer 10

clear outer layer of eye, directs light into eyes and focuses it

Question 11

What is the lens?

Answer 11

behind iris, focuses light on retina

Question 12

What does the iris do?

Answer 12

controls the opening and closing of pupil

Question 13

What is the ciliary muslce?

Answer 13

connects to and helps control iris/lens

Question 14

What is the choroid?

Answer 14

network of blood vessels that supplys the retina, runs between retina and sclera

Question 15

What is the sclera?

Answer 15

white outer layer of eye, maintains shape and protects from injury

Question 16

What is the fovea?

Answer 16

small depression in center of retina where visual acuity is the highest

Question 17

What is the optic disc?

Answer 17

where optic nerve connects to retina, blind spot (no photoreceptors)

Question 18

When looking at the retina with an opthalmoscope how can you tell if its a vein or artery?

Answer 18

veins have wider diameters

Question 19

What is the macula lutea?

Answer 19

surrounds the fovea, looks like a yellow ring

Question 20

What are zonule fibers?

Answer 20

fibers that connect ciliary muslce to lens

Question 21

What is accomodation?

Answer 21

automatic adjustment of the eye to focus

Question 22

What does unaccommodated lens look like?

Answer 22

ciliary muslce tense and zonule fibers pull on lens to flatten it

Question 23

What does accommodated lens look like?

Answer 23

ciliary muslce relax and lens thickens

Question 24

What is emmetropia?

Answer 24

normal 20/20 eyes, the light is focused on the retina properly

Question 25

What is myopia?

Answer 25

near sighted, light is focused before it hits the retina so when it actually reaches the retina its not focused

Question 26

What causes myopia?

Answer 26

too long eye ball or corneal surface is too curved

Question 27

What is hyperopia?

Answer 27

far sighted, light is focused after it hits the retina

Question 28

What causes hyperopia?

Answer 28

too short eye ball or weak refractory system

Question 29

What are the three basic layers of the retina?

Answer 29

ganglion cell layer, bipolar cell layer, photoreceptor layer

Question 30

Where is the pigment epithelium layer located in retina?

Answer 30

outermost layer of retina (beside photoreceptor layer)

Question 31

In what layer does photoreceptors make contact with bipolar cells?

Answer 31

outer plexiform layer

Question 32

In what layer do bipolar cells and amacrine cells make contact with ganglion cells?

Answer 32

inner plexiform layer

Question 33

What are the types of interneurons found in the retina?

Answer 33

horizontal and amacrine

Question 34

What is the purpose of the discs in the outer layer of rod/cone cells?

Answer 34

photoreceptor pigments are held, makes more surface area to absorb light

Question 35

What do cilium do in photoreceptor cells?

Answer 35

convert light energy to neurological stimulus

Question 36

What are the three sections of photoreceptor cells?

Answer 36

outer segment (pigments), inner segment (nucleus), synaptic terminal (synaptic vesicles)

Question 37

What is the traits of rods?

Answer 37

low visual acuity, can see in dark, can't see colour, more of them that cones

Question 38

What is the traits of cones?

Answer 38

high visual acuity, can't see in dark, can see colour, less than rods

Question 39

What is retinitis pigmentosa?

Answer 39

hereditary disease caused by cells in the retina breaking down

Question 40

How does retinitis pigmentosa damage photoreceptors?

Answer 40

epithelial cells stop regenerating photopigments, and begin to destroy outer segments (discs) of rods/cones

Question 41

What are the steps of damage done by pigment epithelium?

Answer 41

discs start to curl, the tip becomes spherical, tip seperates from rod, tip is engulfed by pigment epithelium

Question 42

What are the first symptoms of retinitis pigmentosa?

Answer 42

vision loss starting with night vision and peripheral (rods are damaged firs)

Question 43

What is scotopic vision?

Answer 43

night vision, poor acuity, no colours, only rods

Question 44

What is mesopic vision?

Answer 44

twilight vision, transition between day and night vision, uses cones and rods

Question 45

What is photopic vision?

Answer 45

day vision, well light situations, no rods (saturated) only cones, colour vision, good acuity

Question 46

What is opsin?

Answer 46

membrane protein found in photoreceptor membrane

Question 47

What allows for phototransduction in rods?

Answer 47

rhodopsin

Question 48

What is rhodopsin made up? Where is it found?

Answer 48

opsin and 11-cis-retinal, discs of rod cells

Question 49

When 11-cis retinal absorbs a photon what happens?

Answer 49

isomerizes to All-trans-retinal

Question 50

What is IRBP? What does it do?

Answer 50

made/secreted by photoreceprtors, binds visual retinoids (cis/trans retinal)

Question 51

What happens after All-trans-retinal is made? What does this?

Answer 51

converted to All-trans retinyl ester, then to 11-cis retinol, then back to 11-cis retinal pigment epithelium

Question 52

Do photoreceptors become more positive or negative when activated?

Answer 52

negative (opposite of neuron)

Question 53

What does light activation do to sodium/calcium channels?

Answer 53

closes them (normally open so there is constant influx of Na, Ca)

Question 54

What are the steps of phototransduction in rods?

Answer 54

light enters rhodopsin and makes all-trans retinal, uses transducin to send signal to PDE, which activates the channels (closes them) uses GTP

Question 55

How does cGMP affect phototransduction?

Answer 55

high levels in outer segment keep channels open, light causes levels to drop and channels to close causing hyperpolarization

Question 56

What are rhodopsin kinase involved in?

Answer 56

deactivation pathwya of phototransduction

Question 57

What happens to the membrane potential of a photoreceptor when there is a very intense flash?

Answer 57

more intense means greater hyperpolarization (more negative)

Question 58

What is the difference between rods and cones reactions to same stimulus?

Answer 58

rods: activate fast and deactivate slowly cones: activate fast and deactivate fast

Question 59

Are rods or cones more sensitive to light?

Answer 59

rods are (only takes 1 photon to activate)

Question 60

Why are rods more sensitive to light? Why are cones less sensitive?

Answer 60

many rods connect to a single bipolar cell one cone connects to one bipolar cell

Question 61

What is protanopia?

Answer 61

red is missing (LWS)

Question 62

What is deuteronopia?

Answer 62

green is missing (MWS)