Chapter 2

Question 1

What is the plot of the amount of light absorbed versus the wavelength of the light?

Answer 1

Absorption spectrum

Question 2

A process of adjusting the shape and thickness of the lens. Done in order to produce sharp images even at different distances from the stimulus.

Answer 2

Accommodation

Question 3

This denotes the signal which lasts about 1 millisecond w/c happens from resting potential at (-70 mV) –> (+40 mV) –> negative again –> resting potential again.

Answer 3

Action potential

Question 4

Other than bipolar and ganglion cells, and receptors, what are the two types of neurons that connect neurons across the retina? (2)
Signals traveling between bipolar and ganglion cells use this.

Answer 4

Amacrine cells

Question 5

Eyeball is too long; images of faraway objects are not focused sharply.

Answer 5

Axial myopia

Question 6

_____ is filled with fluid that conducts electrical signals.

Answer 6

Axon

Question 7

Where do signals generated in the receptors travel to first?

Answer 7

Bipolar cells

Question 8

This is a spot where there are no receptors (receptors are missing).

Answer 8

Blind spot

Question 9

This is the key component of neuron. This contains mechanisms to keep the cell alive.

Answer 9

Cell body

Question 10

What do you call a curve that is produced when an observer looks directly at a test light so that it stimulates only the cones in the fovea?

Answer 10

Cone spectral sensitivity curve

Question 11

This occurs when a number of neurons synapse onto a single neuron.

Answer 11

(Neural) Convergence

Question 12

The process of increasing sensitivity to light in the dark

Answer 12

Dark adaptation

Question 13

A function which relates sensitivity to light to time in the dark, beginning when the lights are extinguished.

Answer 13

Dark adaptation Curve

Question 14

“This threshold, the minimum amount
of energy necessary to just barely see the light, is converted to sensitivity; it is measured while the eyes are adapted to the light; 100,000 times greater than the light-adapted sensitivity mea- sured before dark adaptation began”

Answer 14

Dark-adapted sensitivity

Question 15

These parts of the neuron branch out from the cell body to receive electrical signals from other neurons

Answer 15

Dendrites

Question 16

Process which shows the inside of the neuron becoming more positive; causes the charge to change in the direction that triggers an action potential; an excitatory response

Answer 16

Depolarization

Question 17

detachment of retina to pigment epithelium can occur as a result of traumatic injuries of the eye or head, as when a baseball player is hit in the eye by a line drive.

Answer 17

T/F

Question 18

This occurs when the inside of the neuron becomes more positive; one of the two types of responses by the receptor sites.

Answer 18

Excitatory response

Question 19

_____ point is he distance at which light becomes focused on the retina.

Answer 19

Far point

Question 20

It only contains cones. When we look directly at an object, the object’s image falls on this one.

Answer 20

Fovea

Question 21

Where do signals generated in the receptors travel to after the bipolar cells?

Answer 21

Ganglion cells

Question 22

Other than bipolar and ganglion cells, and receptors, what are the two types of neurons that connect neurons across the retina? (2)
Signals travel between receptors through here.

Answer 22

Horizontal cells

Question 23

This condition happens when the focus point for parallel rays of light is located behind the retina, usually because the eyeball is too short.

Answer 23

Hyperopia

Question 24

They are molecules that carry an electrical charge; present in the liquid solution of neurons.

Answer 24

Ions

Question 25

What happens in isomeization?

Answer 25

Retinal changes shape from being bent to straight and detaches from the opsin.

Question 26

These signals (from receptors transported to neurons w/in retina) are transmitted out of the back of the eye in the optic nerve to a group of neurons

Answer 26

Lateral geniculate nucleus

Question 27

20% of the focusing power goes here.

Answer 27

Lens

Question 28

A condition most common in older people, destroys the cone- rich fovea and a small area that surrounds it. This creates a blind region in central vision, so when a person looks directly at something, he or she loses sight of it

Answer 28

Macular degeneration

Question 29

Light of a single wavelength used when measuring one wavelength at a time and the observer's sensitivity to each wavelength

Answer 29

Monochromatic light

Question 30

An inability to see distant objects clearly. The system of this condition brings parallel rays of light into focus at a point in front of the retina, so the image that reaches the retina is blurred.

Answer 30

Myopia

Question 31

This distance at which the lens can no longer accommodate to bring close objects into focus.

Answer 31

Near point

Question 32

filled with fluid that conducts electrical signals

Answer 32

Nerve fiber

Question 33

interconnected groups of neurons

Answer 33

Neural circuits

Question 34

This occurs when one of more neuron synapse into a single neuron.

Answer 34

Neural convergence

Question 35

Electrical signals occur in structures

Answer 35

Neuron

Question 36

These are chemicals released at the end of the neuron

Answer 36

Neurotransmitter

Question 37

This contains both rods and cones and all of the retina outside of the fovea.

Answer 37

Peripheral retina

Question 38

The ease with which a molecule can pass through the membrane; can be seen through the opening of channels (i.e. Na) and can be highly selective to a specific type of molecule.

Answer 38

Permeability

Question 39

a layer that contains enzymes necessary for pigment regeneration.

Answer 39

Pigment epithelium

Question 40

The increasing of distance of the near point as a person gets older.

Answer 40

Presbyopia

Question 41

This is an important property of action potential; once the response is triggered, it travels all the way down the axon without decreasing in size.

Answer 41

Propagated response

Question 42

A hole in the iris from which light passes through. Controls dilation or constriction of the pupil.

Answer 42

Pupil

Question 43

Enhanced perception of short wavelengths during dark adaptation

Answer 43

Purkinje shift (p. 33)

Question 44

These are small areas on the receiving neuron after the synapse; specific to neurotransmitters.

Answer 44

Receptor sites (p. 39)

Question 45

A condition in which the cornea and/or the lens bends the light too much; images of faraway objects are not focused sharply

Answer 45

Refractive myopia (p. 25)

Question 46

The interval between the time one nerve impulse occurs and the next one can be generated in the axon.

Answer 46

Refractory period (p. 37)

Question 47

______ potential is when the axon or nerve fiber is at rest and the difference in potential between the tips of two electrodes is -70 mV, which stays the same as long as there are no signals in the neuron.

Answer 47

Resting potential (p. 36)

Question 48

This condition first attacks the peripheral rod receptors and results in poor vision in the peripheral visual field; it is also generational.

Answer 48

Retinitis pigmentosa (p. 29)


Question 49

A condition wherein there are no cones due to a rare genetic defect.

Answer 49

Rod monochromat (p. 31)

Question 50

A process where cones are more sensitive to light at the beginning of dark adaptation, they control our vision during the early stages of adaptation, so we can’t see what the rods are doing.

Answer 50

Rod adaptation

Question 51

To measure this curve, we measure the sensitivity after the eye is dark adapted (so the rods control vision because they are the most sensitive receptors) and present test ashes in the peripheral retina.

Answer 51

Rod spectral sensitivity curve (p. 33)

Question 52

The place where the rods begin to determine the dark adaptation curve.

Answer 52

Rod–cone break (p. 31)


Question 53

This can be measured by getting 1/threshold. High threshold (i.e. takes a high amt of light to be at the lower level of sensitivity).

Answer 53

Sensitivity

Question 54

neurons specialized to respond to environmental stimuli

Answer 54

Sensory receptor (p. 35)


Question 55

eye’s sensitivity to light as a function of the light’s wavelength.

Answer 55

Spectral sensitivity (p. 32)


Question 56

relationship between wavelength and sensitivity; to see diff wavelengths in the visible spectrum

Answer 56

Spectral sensitivity curve (p. 32)


Question 57

action potentials that occur in absence of stimuli from environment

Answer 57

Spontaneous activity (p. 38)

Question 58

very small space between neurons

Answer 58

Synapse (p. 39)

Question 59

minimum amount of energy necessary to just barely see the light

Answer 59

Threshold

Question 60

transformation of one form of energy into another form of energy; transformation of light energy into electrical energy—occurs in the receptors for vision: the rods and cones

Answer 60

Transduction (p. 26)


Question 61

Ability to see details clearly.

Answer 61

Visual acuity (p. 43)


Question 62

These are molecules which absorb light and found in the outer segments of visual receptors.

Answer 62

Visual pigment (p. 23)


Question 63

A process w/c accounts for change in shape and separation from the opsin causing the molecule to become lighter.

Answer 63

Visual pigment bleaching (p. 31)

Question 64

A process which occurs more rapidly in the cones than in the rods; rods take about 20 to 30 minutes to reach their maximum sensitivity (point R on the curve), compared to only 3 to 4 minutes for the cones (point C) because of this.

Answer 64

Visual pigment regeneration (p. 32)

Question 65

what are the two types of responses that occur at the receptor sites?

Answer 65

excitatory and inhibitory responses

Question 66

When electrical signal reaches the synapse, it triggers a chemical process that causes a new electrical signal in the receiving neuron. Where do the nature of these signals depend on?

Answer 66

type of transmitter released and nature of receptor site in the receiving neuron

Question 67

What increases the chance that a neuron will generate action potentials and is associated with increasing rates of nerve firing?

Answer 67

Excitation

Question 68

What decreases the chance that a neuron will generate action potentials and is associated with lowering rates of nerve firing?

Answer 68

Inhibition