Chapter 8 - Specialized Senses

Question 1

Receptors

Answer 1

• photoreceptors
• mechanoreceptors
• chemoreceptors

Question 2

Receptor Potentials

Answer 2

• sensory receptors have receptor potentials
• used to signal to CNS

Question 3

Sensory Adaptation

Answer 3

• sensory receptors become less sensitive in continued presence of stimulus

Question 4

Sensory Coding

Answer 4

• signals received by receptors are transduced to be understood by brain

Question 5

Visible Spectrum

Answer 5

the wavelengths of light than can be detected by the human eye (400-700 nm)

Question 6

Accessory structures of the eye

Answer 6

• eyebrow/eyelashes
• eyelids

Question 7

Function of eyebrows/eyelashes

Answer 7

protect the eye from sunlight and foreign objects

Question 8

Function of eyelids

Answer 8

spread oil, mucus, and saline across the conjunctiva to moisten and avoid friction

Question 9

Sclera

Answer 9

white part of the eye

Question 10

Iris

Answer 10

color

Question 11

Pupil

Answer 11

central opening; allows light to enter

Question 12

Lens

Answer 12

helps focus light on retina; must be transparent to let light pass through, and must be curved to refract light

Question 13

Choroid

Answer 13

part of the vascular layer

Question 14

Retina

Answer 14

contains photoreceptor cells that capture light

Question 15

Macula

Answer 15

central point of the retina

Question 16

Fovea

Answer 16

center of FOV; contains highest density of rods and cones

Question 17

Optic Nerve

Answer 17

carries visual information to visual cortex

Question 18

Refraction of light in general

Answer 18

change of light speed from one medium to another causes it to bend

Question 19

Refraction of light in the eye

Answer 19

Convex lens refracts light so it converges on a focal point (retina)

Question 20

What allows proper focusing of light?

Answer 20

Accommodation

Question 21

Photons

Answer 21

individual energy particles of light

Question 22

Wavelength

Answer 22

the distance between the peaks of two successive waves

Question 23

refraction

Answer 23

light bending

Question 24

Convex lenses

Answer 24

• thicker in the middle
• allow light to refract and converge at a focal point
• cause the actual image to be focused upside down and reversed from left to right

Question 25

Concave lenses

Answer 25

- thinner in the middle - cause light to be dispersed - useless for focusing images on the retina

Question 26

Fovea

Answer 26

- aka fovea centralis - has high density of CONES

Question 27

Cones

Answer 27

- specialized receptor cells responsible for responding to light - tapered shape compared to rods - responsible for processing images w/ the highest visual acuity (resolution)

Question 28

Accommodation for near sight

Answer 28

adjustment of the shape of the lens to adjust to the distance of the image; controlled by ciliary muscles - ciliary muscles contract, causing them to loosen the tension of the zonular fibers, causing the lens to relax into a spherical, thicker shape, crating increased REFRACTIVE POWER (see images closer to you CLEARER)

Question 29

Accommodation for far sight

Answer 29

- ciliary muscles relax - zonular fibers remain taut and the lens is pulled into a flatter position decreasing the lens' refractive power - allows you to see objects further in FOV

Question 30

What controls the ciliary muscles?

Answer 30

parasympathetic inputs

Question 31

Myopia

Answer 31

nearsightedness - refract light too strongly or the eyeball length is too long - image is focused IN FRONT of the retina - corrected with concave lens

Question 32

Hyperopia

Answer 32

Farsightedness - caused by too little cornea or lens light refraction, or by an eyeball that is too short - image is focused BEHIND the retina - corrected by convex lens that refracts light before it reaches the eye

Question 33

Order of cells from posterior to anterior

Answer 33

- retinal pigment epithelial cells (RPE) - photoreceptor cells (rods/cones) - horizontal cells - bipolar cells - amacrine cells - ganglion cells (axons leading to brain)

Question 34

Retinal pigment epithelial cells (RPE)

Answer 34

lie at the most posterior region of the eyeball, behind the photoreceptor cells and have melanin (traps light) - also store and recycle vitamin A to photoreceptor cells

Question 35

Photoreceptor Layer

Answer 35

contains rod and cone cells (photoreceptor cells) - have specialized regions called OUTER SEGMENTS that capture light and initiate a second messenger cascade into electrical signal.