Sensations And Perceptions Chapter 2

Front 1

Outer Segment

Back 1

The part of a photoreceptor that contains photopigment molecules.

Front 2

Inner Segment

Back 2

The part of a photoreceptor that lies between the outer segment and the cell nucleus

Front 3

Synaptic Terminals

Back 3

The location where axons terminate at the synapse for transmission of information by the release of a chemical transmitter

Front 4

Chromophore

Back 4

The light-catching part of the visual pigments of the retina

Front 5

Rhodopsin

Back 5

The visual pigment found in rods

Front 6

Melanopsin

Back 6

A photopigment that is sensitive to ambient light

Front 7

Photoactivation

Back 7

Activation by light

Front 8

Hyperpolarization

Back 8

An increase in membrane potential such that the inner membrane surface becomes more negative than the outer membrane surface

Front 9

Graded potential

Back 9

An electrical potential that can vary continuously in amplitude

Front 10

Eccentricty

Back 10

The distance between the retina; image and the fovea

Front 11

Aging-related macular degeneration (AMD)

Back 11

A disease associated with aging that affects the macula. AMD gradually destroys sharp central vision, making it difficult to read, drive, and recognize faces. There are two forms of AMD: Wet and dry.

Front 12

Macula

Back 12

The central part of the retina that has a high concentration of cones.

Front 13

Fovea

Back 13

A small pit, near the center of the macula that contains the highest concentration of cones, and no rods. It is the portion of the retina that produces the highest visual acuity and serves as the point of fixation

Front 14

Scotoma

Back 14

A blind spot in the visual field

Front 15

Horizontal cell

Back 15

A specialized retinal cell that contacts both photoreceptor and bipolar cells

Front 16

Lateral Inhibition

Back 16

Antagonistic neural interaction between adjacent regions of the retina

Front 17

Amacrine cell

Back 17

A retinal cell found in the inner synaptic contacts with bipolar cells, ganglion cells, and other amacrine cells

Front 18

Bipolar cell

Back 18

A retinal cell that synapses with either rods or cones (NOT BOTH) and with horizontal cells, and then passes the signals on to ganglion cells

Front 19

Diffuse bipolar cell

Back 19

A bipolar retinal cell whose processes are spread out to receive input from multiple cones

Front 20

Sensitivity

Back 20

1. The ability to perceive via the sense organs.
2. Extreme responsiveness to radiation, especially to light of a specific wavelength.
3. The ability to respond to transmitted signals.

Front 21

Visual acuity

Back 21

A measure of the finest detail that can be resolved by the eyes.

Front 22

Midget bipolar cell

Back 22

A small bipolar cell in the central retina that receives input from a single cone

Front 23

ON bipolar cell

Back 23

A bipolar cell that responds to an increase in light captured by the cones

Front 24

OFF bipolar cell

Back 24

A bipolar cell that responds to a decrease in light captured by the cones.

Front 25

Ganglion cell

Back 25

A retinal cell that receives visual information from photoreceptors via two intermediate neuron types (bipolar and amacrine cells) and transmits information to the brain and midbrain

Front 26

P ganglion cell

Back 26

A small ganglion cell that receives excitatory input from single midget bipolar cells in the central retina and feeds the parvocellular layer of the lateral geniculate nucleus

Front 27

M ganglion cell

Back 27

A ganglion cell resembling a little umbrella that receives excitatory input from diffuse bipolar cells and feeds the magnocellular layer of the lateral geniculate nucleus

Front 28

Koniocellular cell

Back 28

A neuron located between the magnocellular layer and parvocellular layers of the lateral geniculate nucleus. This layer is known as the kniocellular layer.

Front 29

Receptive field

Back 29

The region on the retina in which visual stimuli influence a neurons firing rate.

Front 30

ON-center cell

Back 30

A cell that depolarizes in response to an increase in light intensity in its receptive-field center

Front 31

OFF-center cell

Back 31

A cell that depolarizes in response to a decrease in light intensity in its receptive-field center

Front 32

Filter

Back 32

An, acoustic electrical, electronic, or optical device, instrument, computer program, or neuron that allows the passage of some frequencies or digital elements and blocks the passage of others

Front 33

Contrast

Back 33

The difference in luminance between an object and the background, or between lighter and darker parts of the same object

Front 34

Retinitis Pigmentosa (RP)

Back 34

A progressive degeneration of the retina that affects night vision and periphera vision. RP commonly runs in families and can be caused defects in a number of different genes that have recently been identified