The Special SensesThe Special SensesA. Visual sensationsA. Visual sensations 1. Accessory structures of the 1. Accessory structures of the eyeeye 2. Anatomy of the eyeball2. Anatomy of the eyeball a. Fibrous tunica. Fibrous tunic b. Vascular tunicb. Vascular tunic c. Retina (nervous tunic)c. Retina (nervous tunic) d. Lensd. Lens e. Interior of the eyeballe. Interior of the eyeball 3. Image formation3. Image formation a. Refraction of light raysa. Refraction of light rays b. Accommodation and b. Accommodation and

near point of vision near point of vision c. Constriction of the pupilc. Constriction of the pupil 4. Convergence4. Convergence

5. Physiology of vision5. Physiology of vision a. Photoreceptors and a. Photoreceptors and photopigmentsphotopigments b. Receptor potential andb. Receptor potential and neurotransmitter releaseneurotransmitter release 6. Visual pathway6. Visual pathwayB. Auditory sensationsB. Auditory sensations 1. External (outer) ear1. External (outer) ear 2. Middle ear2. Middle ear 3. Internal (inner) ear3. Internal (inner) ear 4. Physiology of hearing4. Physiology of hearing 5. Physiology of equilibrium5. Physiology of equilibrium

Surface Anatomy and Accessory Surface Anatomy and Accessory Structures of the EyeStructures of the Eye

1. eyelids2. eyelashes3. eyebrows4. extrinsic eye muscles5. lacrimal apparatus

Lacrimal ApparatusLacrimal Apparatus

1. lacrimal gland1. lacrimal gland

2. lacrimal ducts2. lacrimal ducts

3. lacrimal puncta3. lacrimal puncta

4. lacrimal canals4. lacrimal canals

5. nasolacrimal duct5. nasolacrimal duct

Anatomy of the EyeballAnatomy of the Eyeball

1. fibrous tunic1. fibrous tunic

a. corneaa. cornea

b. sclerab. sclera

______________________________

canals of Schlemmcanals of Schlemm

Sclera pupil iris

Anatomy of the Eyeball Con’tAnatomy of the Eyeball Con’t

2. vascular tunic2. vascular tunic a. choroida. choroid b. ciliary bodyb. ciliary body (1) ciliary muscle(1) ciliary muscle (2) ciliary processes(2) ciliary processes c. irisc. iris (1) sphinctor pupillae(1) sphinctor pupillae (2) dilator pupillae(2) dilator pupillae

Dilator pupillae Sphinctor pupillae

Constriction Dilation

Anatomy of the Eyeball Con’tAnatomy of the Eyeball Con’t3. nervous tunic (retina)3. nervous tunic (retina)

a. pigmented layera. pigmented layer

b. nervous layerb. nervous layer

Terms: fovea centralisTerms: fovea centralis

optic discoptic disc

(blind spot)(blind spot)

Anatomy of the Eyeball, Con’tAnatomy of the Eyeball, Con’t

3. b. nervous layer3. b. nervous layer (1) photoreceptor layer(1) photoreceptor layer (a) rods(a) rods (b) cones(b) cones (2) bipolar layer(2) bipolar layer (a) bipolar cells(a) bipolar cells (b) amacrine cells(b) amacrine cells (c) horizontal cells(c) horizontal cells (3) ganglion cell layer(3) ganglion cell layer

LensLens

1. biconvex1. biconvex

2. crystallins2. crystallins

3. suspensory ligaments3. suspensory ligaments

4. focuses light4. focuses light

Ciliary body

Ciliary Processes

lens

Suspensoryligaments

Canals of Schlemm

iris

Cavities of the EyeCavities of the Eye1. anterior cavity1. anterior cavity

a. posterior chambera. posterior chamber

b. anterior chamberb. anterior chamber

c. aqueous humorc. aqueous humor

d. fluid flowd. fluid flow

e. canals of Schlemme. canals of Schlemm

f. intraocular pressuref. intraocular pressure

Anterior Chamber

Posterior Chamber

2. posterior cavity a. vitreous humor b. tugor c. not replaced

The formation of images on the The formation of images on the retina involves three processes:retina involves three processes:1. refraction of light rays1. refraction of light rays

2. accommodation of the lens2. accommodation of the lens

3. constriction of the pupil3. constriction of the pupil

Refraction of LightRefraction of Light

1. light passes through1. light passes through

different mediadifferent media

2. light bends at 2. light bends at

interfacesinterfaces

3. 60% at cornea3. 60% at cornea

4. 40% by lens4. 40% by lens

AccomodationAccomodation1. biconvex lens1. biconvex lens

2. point of intersection2. point of intersection

3. near object = more 3. near object = more convexconvex

4. far object = less convex4. far object = less convex

5. role of ciliary muscle5. role of ciliary muscle

Constriction of the PupilConstriction of the Pupil

1. part of accommodation reflex1. part of accommodation reflex

2. limits peripheral light2. limits peripheral light

Convergence of the EyesConvergence of the Eyes

1. single binocular vision1. single binocular vision

2. corresponding points2. corresponding points

3. complementary photoreceptors3. complementary photoreceptors

4. near vision = medial rotation of eyes4. near vision = medial rotation of eyes

The Visual ProcessThe Visual Process

PhotoreceptorsPhotoreceptors1. central fovea1. central fovea

2. visual axis2. visual axis

3. rods and cones3. rods and cones

4. outer segments4. outer segments

5. visual pigments5. visual pigments

6. glutamate6. glutamate

7. dark vs light 7. dark vs light

conditionsconditions

Visual AcuityRod cells

not present in central fovea

increase in concentration to ora serrata

dim light and peripheral vision

100% cone cells in central fovea

diminish in number toward ora serrata

three different types: blue, red, green cone cells

bright light required to break pigments

1:1 relationship with bipolar cells

visual acuity and color vision

6 – 600 rod cells converge on 1 bipolar cell, as well as amacrine and horizontal cells.

Cone cells

PhotoreceptorsPhotoreceptors

DARK

rod cell Na+ channels open

membrane depolarizes

Na+ inflow stimulates glutamate release

glutamate inhibits bipolar cells

LIGHT

rod cell Na+ channels close

membrane hyperpolarizes

no Na+ inflow prevents glutamate release

bipolar cells initiate action potential

visual pathway started

visual pathway startedX

DARK VERSUS LIGHT CONDITIONS

Dark versus light conditionsDark versus light conditions

The Visual PathwayThe Visual Pathway

The visual pathway begins with The visual pathway begins with stimulation of the bipolar neurons by stimulation of the bipolar neurons by photoreceptor cells.photoreceptor cells.

1. 6 - 600 rod cells converge on 1 1. 6 - 600 rod cells converge on 1 bipolar cell, as well as amacrine and bipolar cell, as well as amacrine and horizontal cellshorizontal cells2. Cone cells have a 1:1 relationship 2. Cone cells have a 1:1 relationship with bipolar cellswith bipolar cells

Visual PathwayVisual Pathway1. bipolar cells1. bipolar cells2. ganglion cells2. ganglion cells3. optic nerve (II)3. optic nerve (II)4. optic chiasma4. optic chiasma

a. medial retina vsa. medial retina vs b. lateral retinab. lateral retina

5. optic tracts5. optic tracts6. thalamus6. thalamus7. optic radiations7. optic radiations8. primary visual areas8. primary visual areas

Hearing and EquilibriumHearing and Equilibrium

External EarExternal Ear

Auricle (pinna)

External auditory meatus

Tympanic membrane

Ceruminous glands

Middle EarMiddle Ear1. petrous portion of1. petrous portion of

temporal bonetemporal bone2. mastoid air cells2. mastoid air cells3. auditory tube3. auditory tube4. ossicles4. ossicles

________________________________5. oval window5. oval window6. round window6. round window

Auditory OssiclesAuditory Ossicles

1. malleus1. malleus

2. incus2. incus

3. stapes3. stapes

________________________

stapediusstapedius

tensor tympanitensor tympani

Internal EarInternal Ear1. bony labyrinth1. bony labyrinth

a. 3 semicircular canalsa. 3 semicircular canals (1) frontal(1) frontal (2) horizontal(2) horizontal (3) sagittal(3) sagittal b. vestibuleb. vestibule c. cochleac. cochlea________________________________perilymphperilymph

Internal EarInternal Ear

1. bony labyrinth1. bony labyrinth a. 3 semicircular canalsa. 3 semicircular canals (1) frontal(1) frontal (2) horizontal(2) horizontal (3) sagittal(3) sagittal b. vestibuleb. vestibule c. cochleac. cochlea________________________________perilymphperilymph

Internal EarInternal Ear

2. membranous labyrinth2. membranous labyrinth

a. 3 semicircular ductsa. 3 semicircular ducts

b. utricle and sacculeb. utricle and saccule

c. cochlear ductc. cochlear duct

__________________________________

endolymphendolymph

CochleaCochlea1. scala vestibuli1. scala vestibuli

2. scala tympani2. scala tympani

3. scala media3. scala media

(cochlear duct)(cochlear duct)

CochleaCochlea1. scala vestibuli1. scala vestibuli

2. scala tympani2. scala tympani

3. scala media3. scala media

(cochlear duct)(cochlear duct)

4. vestibular membrane4. vestibular membrane

5. basilar membrane5. basilar membrane

6. spiral organ of Corti6. spiral organ of Corti

7. 16,000 hair cells7. 16,000 hair cells

8. tectorial membrane8. tectorial membrane

Physiology of HearingPhysiology of Hearing

Physiology of HearingPhysiology of Hearing

How do you detect differences in How do you detect differences in pitch?pitch?

Physiology of EquilibriumPhysiology of Equilibrium

1. static equilibrium (saccule and utricle)1. static equilibrium (saccule and utricle)

perception of head orientation when the perception of head orientation when the

body is stationarybody is stationary

2. dynamic equilibrium (mainly semicircular 2. dynamic equilibrium (mainly semicircular ducts) perception of motion or accelerationducts) perception of motion or acceleration

(linear vs angular) *linear acceleration-(linear vs angular) *linear acceleration-utricle and sacculeutricle and saccule

Static EquilibriumStatic Equilibrium1. utricle and saccule1. utricle and saccule

2. hair cells2. hair cells

3. otoliths of macula3. otoliths of macula

4. inertia4. inertia

Dynamic EquilibriumDynamic Equilibrium1. semicircular ducts1. semicircular ducts

2. hair cells2. hair cells

3. ampullae3. ampullae

4. cupula4. cupula

5. inertia5. inertia