Special Senses

Question 1

What are the five special senses?

Answer 1

Vision, Taste, Smell, Hearing, & Equilibrium

Question 2

Three layers ( tunics ) of the eye

Answer 2

Fibrous layer: outermost layer ( consists of the sclera & cornea )
Vascular layer: middle pigmented layer of eye ( consists of the choroid region, ciliary body, & iris )
Inner layer: colored part of eye that lies between cornea and lens ( contains the pupil )

Question 3

The two regions of the fibrous layer and their function

Answer 3

Sclera: opaque posterior region, protects & shapes eyeball, & anchors extrinsic eye muscles
Cornea: transparent anterior portion of fibrous layer & forms clear window that lets light enter and bends light as it enters the eye )

Question 4

Three regions of the Vascular Layer & Function of Pupil

Answer 4

Choroid Region: supplies blood to all layers of eyeball
Ciliary Body: consists of smooth muscle bundles, ciliary muscles, that control shape of lens
Iris: pupils: central opening that regulates amount of light entering eye

Question 5

Parasympathetic vs. Sympathetic control of pupil constriction and dilation

Answer 5

Parasympathetic control: close vision and bright light cause sphincter pupillae ( circular muscles ) to contract and pupils to constrict
Sympathetic control: distant vision and dim light cause dilator pupillae ( radial muscles ) to contract and pupils to dilate

Question 6

Two regions of inner layer ( retina ) and their functions

Answer 6

Retina: contains millions of photoreceptor cells that transduce light energy
Lens: changes shape to precisely focus light on retina

Question 7

What is the optic disc?

Answer 7

Site where optic nerve leaves eye ( lacks photoreceptors, so referred as blind spot )

Question 8

Difference in function between rods and cones

Answer 8

Rods: very sensitive to light, best suited for night vision and peripheral vision, contains single pigment, & pathways converge, causing fuzzy, indistinct images
Cones: vision receptors for bright light, high-resolution color vision, have one of three pigments for colored view, results in detailed, high resolution vision, & color blindness, lack of one or more cone pigments

Question 9

Convex vs. Concave lens: which one converges vs disperses light?

Answer 9

Convex Lens: converges light
Concave Lens: disperses light

Question 10

Where are the three places light is refracted as it is entering the eye?

Answer 10

entering cornea, entering lens, & leaving lens

Question 11

Adaptation of the eyeball of distant versus close vision

Answer 11

Distant vision: Ciliary muscles are completely relaxed in distance vision and lenses are stretched flat
Close vision: requires eye to make active adjustments of the lenses, constriction of the pupils, & convergence of the eyeballs

Question 12

Myopia, Hyperopia, and Astigmatism - what is the detect found for each one and what type of lens corrects each one?

Answer 12

Myopia: ( nearsightedness ) eyeball is too long, so focal point is in front of retina ( corrected with a concave lens )
Hyperopia: ( farsightedness ) eyeball is too short, so focal point is behind the retina ( corrected with a convex lens )
Astigmatism: unequal curvatures in different parts of cornea or lens ( corrected with cylindrically ground lenses or laser procedures )

Question 13

What are the two chemical special senses? What does this mean?

Answer 13

Smell ( olfaction ) & Taste ( gustation ): complementary senses that let us know whether a substance should be savored and avoided

Question 14

Three regions of the ear

Answer 14

External ( outer ) layer: hearing only
Middle layer: hearing only
Inner ( Internal ) Ear: hearing and equilibrium

Question 15

Function of the tympanic membrane

Answer 15

Vibrates in response to sound and transfers sound energy to bones of middle ear

Question 16

Know the auditory ossicles - what is their function?

Answer 16

Three small bones in tympanic cavity, named for their shape: malleus ( the hammer is secured to eardrum ), incus, & stapes ( the stirrup base fits into oval window )

Question 17

What are the three regions of the internal ear?

Answer 17

Bony Labyrinth: system of tortuous channels and cavities that worm through bone
Membranous Labyrinth: series of membranous sacs and ducts contained in bony labyrinth
Vestibule: contains two membranous sacs ( sacs house equilibrium receptor regions that respond to gravity and changes in position of head )

Question 18

Function of semicircular canals

Answer 18

Three canals oriented in three plans of space: anterior, lateral, & posterior ( receptors respond to angular movements of the head )

Question 19

Pathway of sound to the internal ear

Answer 19

external acoustic meatus -> tympanic membrane -> malleus -> stapes -> oval window

Question 20

Conduction vs. Sensorineural Deafness

Answer 20

Conduction deafness: blocked sound conduction to fluids of internal ear & causes include impacted earwax, perforated eardrum, otitis media, & otosclerosis of the ossicles
Sensorineural deafness: damage to neural structures at any point from cochlear hair cells to auditory cortical cells ( typically from gradual hair cell loss )