CHAPTER 6: THE EYE

Question 1

What is sensation?

Answer 1

Involves cells in the nervous system that are specialized to detect stimuli from the environment.

Question 2

What is perception?

Answer 2

Conscious experience and interpretation of information from the senses.

Question 3

What allows the eye to detect light stimuli?

Answer 3

photoreceptors in the eye

Question 4

What wavelength of electromagnetic radiation is visible to us?

Answer 4

between 380 nm and 760 nm.

Question 4

What wavelength of electromagnetic radiation is visible to us?

Answer 4

between 380 nm and 760 nm.

Question 5

What is hue?

Answer 5

dominant wavelength

Question 6

What is brightness?

Answer 6

intensity

Question 7

What is saturation?

Answer 7

purity

Question 8

At what speed does light travel?

Answer 8

300 000km per second

Question 9

Slower oscillations= ….. wavelengths?

Answer 9

longer

Question 10

What happens if the radiation contains all visible wavelength ?

Answer 10

no sensation of hue, appears white.

Question 11

What is a sensory receptor?

Answer 11

• specialized neuron

- detects a particular category of physical events

Question 12

What is sensory transduction?

Answer 12

process by which sensory stimuli are transduced into slow, graded receptor potentials-

Question 13

What is a receptor potential?

Answer 13

-Slow- graded electrical potential produced by a receptor cell in response to a physical stimuli

Question 14

What part of the eye must the image be focused on?

Answer 14

• the retina

- focus is aided by bones and muscles surrounding the eye.

Question 15

What are the eyes suspended in ?

Answer 15

the orbits

Question 16

How is the eye help in place and moved?

Answer 16

-by extraocular muscles attached to the sclera

Question 17

What are the conjunctiva?

Answer 17

mucous membranes that line the eyelid and fold back to attach to the eye.

Question 18

What is responsible for regulating the amount of light entering the eye?

Answer 18

pupils

Question 19

What is responsible for accomodation?

Answer 19

• the lens

- control by ciliary muscles

Question 20

What are the three cellular layers of the retina?

Answer 20

From BACK to FRONT:

• photoreceptive (rods and cones)
• bipolar cells
• ganglion cells

Question 21

Are there more rods or cones in the retina?

Answer 21

more rods than cones

Question 22

What are rods responsible for?

Answer 22

-low intensity light vision

Question 23

What are cones responsible for?

Answer 23

acuity, colour vision, daytime vision

Question 24

What is the fovea?

Answer 24

• central region of the retina
• contains only cones
• most acute vision.

Question 25

What is the optic disk?

Answer 25

• back of the eye
• no receptors
• blind spot
• exit point of axons

Question 26

What is transduction?

Answer 26

• process by which energy from the environment is converted to a change in membrane potential in a neuron
• converts external stimuli into internal stimuli

Question 27

What are photopigments?

Answer 27

• responsible for transduction
• embedded in lamella (layer of membrane)
• consist of an opsin and a retinal.

Question 28

How many photopigments a rod contain?

Answer 28

10 million

Question 29

What is a receptive field?

Answer 29

place a visual stimulus must be located to produce a response in a neuron

Question 30

What does the location of the receptive field of a particular neuron depend on?

Answer 30

location of photoreceptors that provide it with visual information.

Question 31

What are vergence movements ?

Answer 31

cooperative movement that keep eyes both on the same target.

Question 32

What are saccadic movements?

Answer 32

shift of gaze abruptly from one point to another

Question 33

What are pursuit movements?

Answer 33

movement that eyes make to maintain an image of a moving object on the fovea.

Question 33

What are pursuit movements?

Answer 33

movement that eyes make to maintain an image of a moving object on the fovea.

Question 34

What are the optic nerves?

Answer 34

• back of the eye
• bundles of axons of ganglion cells
• convey info to dorsal lateral geniculate nucleus (LGN)
• join together at base of brain to form optic chiasm

Question 35

What are the main steps of the visual pathway?

Answer 35

• photoreceptors of the retina
• info sent to rest of brain via optic nerves to LGN
• neurons in LGN send axons to primary visual cortex
• info sent to visual association cortex