lec 10 sensation and vision

Question 1

what happens when we see light?

Answer 1

-eyes receive light energy, then transform it into neural message

-then brain processes into what we consciously see (colour, etc)

Question 2

what are the main parts of the eye? what is their main function? (6)

Answer 2

cornea- protects eye

pupil-small adjusting opening

iris (colored part)- dilates or restricts pupil in response to light intensity

lens- changes in curvature or thickness to focus on near or far objects

retina- transduction into neural impulses to send to optic nerve

optic nerve- sends neural impulses to brain

Question 3

when looking at light, what does each part of the eye do?

Answer 3

-passes thru cornea, bends light to provide focus

-passes thru pupil controlled by iris

-passes thru lens, light is focused +inverted

-light lands on retina, then sent to optic nerve

Question 4

if the image on our eye is inverted, how do we see everything right-side up?

Answer 4

-retina itself doesn’t see whole image

-rather, millions of receptor cells convert light energy into neural impulses

-neural impulses sent to brain, then reassembled into perceived upright image

Question 5

What happens when light enters the retina

Answer 5

-light enters, triggering rods and cones

-photochemical reactions –> neural impulses

-neural impulses–>bipolar cells

-bipolar cells –> ganglion cells

-ganglion cells axons intertwine to form the optic nerve

Question 6

where does optic nerve carry info to?

Answer 6

thalamus, stands ready to distribute info

Question 7

what is the area missing from our retina’s in each eye called? why does this happen?

Answer 7

blind spot

no receptor cells where optic nerve leaves eye

Question 8

how do we compensate for blindspots?

Answer 8

2 ways

• blind spot on eyes are in different spots, so they compensate for each other

-eyes constantly moving, so brain will fill in missing info with all the info our eyes take in

Question 9

what do rods do? where are they located in retina?

Answer 9

-help is see black and white actions in peripheral view

-helps us see in dark

-located in periphery

Question 10

why is our peripheral vision dull

Answer 10

several rods will share a bipolar cell, sending combined messages

Question 11

what happens with rods in respect to dim light?

Answer 11

sensitive in dim light

b/c they share their energy output onto the single bipolar cell

Question 12

true or false: cones are more common than rods

Answer 12

false, rods are abt 20x more common than cones

Question 13

what are the functions of cones? where are they located in retina?

Answer 13

-sharp, colorful details in bright light

-center of retina

Question 14

where do cones transmit their info?

Answer 14

SINGLE bipolar cell

-helps relay cone’s individual message to visual cortex

-precise info

Question 15

what is the main difference b/w rods and cones?

Answer 15

rods: mixing of multiple signals to create single message

cone: single message from start to finish

Question 16

monocular cues: what is an illusion?

Answer 16

False/misleading perceptions

Question 17

monocular cues: how does light allow us to determine depth?

Answer 17

Nearby objects reflect more light than more distant objects

Given two identical objects, dimmer one appears to be farther

Question 18

explain reflex arc

Answer 18

1. pain message sent up sensory neuron
2. reaches interneurons in spinal cord, info processed
3. signal travels down motor neuron to generate reflex

Question 19

what are the 3 things that make a sensory neuron sensory?

Answer 19

1. exposed to correct environment
2. must contain receptors capable of being activated by environment
3. must be connected centrally

Question 20

what are the five sensory receptors in humans? Include their stimulus and what senses they correspond too.

Answer 20

1. Chemo: chemicals (taste/smell)
2. Photo: light (vision)
3. Mechano: physical changes (touch, hearing, balance)
4. Thermo: temp (thermoreception)
5. Pain: pain (pain)