special senses - lab supplement

8/7/2019 Special Senses - Lab Supplement

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S p e c i a lS e n s e s

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S P E C I A L SE~SES-VisionIIEye-External Structure

D e s c r i p t i o n The eyeball rests in the orbit in the skull and is surrounded by fatty tissue. Six major muscles cothe movement of the eyeball:- IMuscle Name Action-Superior rectus Elevates eyeInferior rectus Depresses eyeMedial rectus Moves eye mediallyLateral rectus Moves eye laterallySuperior oblique Depresses eye and laterally rotates eye

~erior oblique Elevates eye and laterally rotates eye

The lacrimal gland produces tears that are spread across the surface of the eye during blinking.tears accumulate in a pooling area called the medial canthus. Then they enter openings calledsuperior lacrimal punctum and the inferior lacrimal punctum, which lead to passagewayscalledsuperior lacrimal caniculus and the inferior lacrimal caniculus. From here they travel tolacrimal sac and down the nasolacrimal duct and are drained into the nose. This explains whynose runs when you are crying heavily.

S t u d y T ip The Lacrimal gland is located on the Lateral side of the eyeball. Use it as a landmark.

1. Superior lacrimal punctum (opening)2. Superior lacrimal caniculus3. Lacrimal sac4. Inferior lacrimal punctum (opening)5. Inferior lacrimal caniculus6. Nasolacrimal duct7. Opening of nasolacrimal duct

8. Superior oblique muscleg. Superior rectus muscle10. Lateral rectus muscle11. Inferior oblique muscle12. Inferior rectus muscle13. Medial rectus muscle

K e y t o I l l u s t r a t i o n

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S P E C I A L S E N S E S -V i s i o nEye-External Structu

Lacrimalgland

(

Trochlea1

9

redialcanthusLacrimalgland

13Inferiornasalconcha

7 )\. . ~ ~

~)ILacrimal apparatus Eyeball

anterior view Note:Arrowsindicatethe directionthe eyewill movewhen amuscle iscontracted.

7. _8. _9. _10. _11.12.13.

1.2. _3. _4. _5. _6. _

8 Trochlea13

11

Eyeball in orbitlateral view 12

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Eye-Internal StructureS P EC IA L SENSES -V is ion

D e s c r i p t i o n

A n a l o g vS t u d y T i p

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The eye is divided into three tunics or sheaths: fibrous tunic, vascular tunic, and neural tunic.fibrous tunic is a thick, tough layer of connective tissue and consists of the sclera (white of the eyeon its posterior portion and becomes the transparent cornea on its anterior portion. The cornecup-shaped and filled with a liquid called aqueous humor. The vascular tunic consists of the vascdark brown choroid coat on its posterior portion, which becomes the ciliary body, and the iris (colpart of the ey e) on its anterior portion.The lens of the eye is held in place by suspensory ligaments that anchor it to the ciliary bWhen the smooth muscle in the ciliary body contracts, it can change the shape of the lens, allowthe eye to focus on near versus distant objects. The iris covers the front of the lens. In the centethe iris is a hole called the pupil, which allows light to enter the eye. Dilation and constriction ofpupil controls the amount of light that enters the eye. The neural tunic is the retina and coversthe posterior portion of the eye. This thin layer contains photoreceptors called cones and rods. Rhelp us see in low-light situations, and cones help us see color and give us sharper, clearer images.Filling the posterior cavity of the eye is a jelly-like substance called vitreous humor. It maint

the normal shape of the eyeball. On the back of the retina is a small disc called the macula luwhich contains cones but no rods. At the center of this structure is a shallow depression calledfovea centralis, which has the highest concentration of cones and gives us our sharpest visioncontrast, the one region of the retina that lacks photoreceptors is called the optic disc (b lin d spot) .images form here. It is located where the optic nerve leaves the eye.

The macula lutea is like a target and the fovea centralis is like the bullseye.

To recall the order of the layers in the back of the eye, use the mnemonic: Scared Cats Run. Tindicates the layers from outermost to innermost or Sclera, Choroid, Retina.

K e v t o I l l u s tr a t i o n1. Iris2. Cornea3. Edge of pupil4. Lens5. Anterior chamber (filled with aqueous humor)6. Posterior chamber (filled with aqueous humor)7. Anterior cavity8. Suspensory ligaments

9. Ciliary body10. Posterior cavity (filled with vitreous humor)11. Central vein12. Central artery13. Optic nerve14. Fovea centralis15. Macula lutea16. Optic disc (blind spot)


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SPEC IAL SENSES -V is ioEye-Internal Struc

Color a/l the differentlayers different colors.

To recall the layers onthe posterior portion ofthe eyeball:

ScleraScaredCatsRun!

ScleraChoroidRetina

The macula lutea islike the target and thefovea centralis is thebullseye.

2

124

11

10Blood vesselsin choroid coat

1. _2. _3. _4. _5. _6. _7. _8. _

9. _10. _11. _12. _13. _14. _15. _16. _

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Ear-General StructureS P E C IA L S E N S E S -H e a r i n g l E q u i l i b r i u m

@I 3M


A n a l o g y

2 6 6

The ear isdivided into three regional areas: external ear, middle ear, and inner ear. The externalextends from the ear itself to the tympanic membrane. The auricle is made of elastic cartilagedirects sound waves into the external auditory meatus. At the end of this passagewayis the delictympanic membrane or eardrum. This cone-shaped connective tissue vibrates when sound wastrike it.The middle ear is an air-filled space that extends medial to the tympanic membrane and up

the inner ear. It contains three ear ossicles: malleus, incus, and stapes. These bones act as a lesystem to both transmit and amplify sound waves from the tympanic membrane to the inner ear. Tauditory tube, or Eustachian tube, connects the middle ear to the nasopharynx. Because this tubshort and horizontal in children it is easier for bacteria to enter the middle ear, causing middleinfections. The function of this tube is to equalize pressure on both sides of the tympanic membranThe inner ear is a bony complex of fluid-filled chambers that contain receptors for both hear

and equilibrium. The receptors for equilibrium are located in the semicircular canals, and thosehearing are located in the cochlea. As the ear ossicles vibrate, they transfer vibration to the owindow of the inner ear. This sends a shock wave through fluid-filled chambers within the cochlwhich are eventually dissipated out through the round window to the air in the tympanic caviThis vibration stimulates hair cells in the organ of Corti.Each hair cell is linked to a nerve fiber. The hair cell transforms this mechanical, vibrationforce into an electrical stimulus that carries nervous impulses along the cochlear nerve branch totemporal lobe in the cerebrum, where it is interpreted as sound.

The tympanic membrane looks like the cones on a stereo speaker. The malleus looks like a hammthe incus looks like an anvil, and the stapes looks like a stirrup. The cochlea of the inner ear lolike a snail shell.

K e y t o I l l u s t r a t i o n1. Auricle2. Lobule3. External auditory meatus4. Tympanic membrane5. Tympanic cavity6. Malleus7. Incus8. Stapes9. Eustachian (auditory) tube10. Semicircular canals11. Vestibular branch of auditory nerve12. Facial nerve13. Cochlear branch of auditory nerve14. Cochlea15. Anterior semicircular canal16. Semicircular ducts17. Lateral semicircular canal

18. Posterior semicircular canal19. Stapes in oval window20. Round window21. Organ of Corti22. Cochlear duct23. Saccule24. Utricle25. Vestibular duct26. Cochlear duct27. Tympanic duct28. Tectorial membrane29. Stereocilia30. Outer hair cells31. Supporting cells32. Basilar membrane33. Inner hair cell34. Nerve fibers of cochlear nerve


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S P E C I A L S E N S E S -H e a r i n g / E q u i l i h r i u mEar-General Structure

Malleus ~looks like -~'\a hammer. ~~-:;:n-~ ~ Incus lookslike an anvil.The tympanic membranelooks like the coneson a stereo speakerand vibrates like it too.

eo~/ ~ ~ ~ ~ " " " - - - ~ Stapes looks

like a stirrup.'~ Inner ear~\: ',,,,

12

13

14

218

Cochlea lookslike a snail shell.

3031

28 Inner Earinternal view 25

34Nervefibers

32 Organ of Corti

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S P E C IA L S E N S E S - T a s teTongue to Taste Buds

D e s c r i p t i o n The surface of the tongue iscovered with many small epithelial projections called papillae. Therethree different types of papillae: filiform, fungiform, and circumvallate. The filiform papillaelocated on the tip of the tongue; the fungiform papillae are located posterior to the filiform; andcircumvallate papillae are found in a "V" shaped strip along the posterior margin of the tongue.Taste buds are located along the sides of the papillae. Each type of papilla contains a diffe

number of taste buds. In total, the average adult has about 10,000 taste buds but this numdecreases with age.A taste bud is composed of two different types of cells-gustatory (taste) cellssupporting cells.The gustatory cells are modified neurons that have microvilli ( ta ste h a ir s) that protrude onto

surface of a papilla. Chemicals in food bind at receptors in these microvilli, which trigger a nervimpulse in the gustatory cells. This follows a nerve pathway to the gustatory cortex in the cerebof the brain where the taste is interpreted.

A n a l o g y The fungiform (fungus, mushroom) papilla is dome-shaped like a mushroom cap, and the filif(f i lum, thread) papilla looks like a flame.

K e y t o I I I u s t r a t i o n1. Epiglottis2. Palatopharyngeal arch3. Palatine tonsil4. Palatoglossal arch

5. Lingual tonsi l6. Circumvallate papilla7. Fungiform papilla8. Filiform papilla

9. Taste bud10. Gustatory (taste) cells11. Supporting cells12. Microvilli ( ta st e ha ir s)

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S P E C IA L S E N S E l' Y~.asteTongu e to T as te B u

1

5Shaped like amushroom cap 6

No tastebudspresent

7.

8.

1.2 .=------3.4.5.6 .= -----= -

9Stratified squam ousepithelium

Color thedifferentpapillae.

11

Looks likea flame

Taste Buds

7.8.-----9.

10.11.12.------

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Sense of SmellS P E C I A L S E N S E S -O l f a c t i o n


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Olfaction refers to the sense of smell. Let's follow what occurs when you smell a cup of coAs you inhale air through the nostrils it enters the nasal cavity and the nasal conchae prodturbulent airflow.This disperses the air and delivers aromatic molecules to the two olfactory orglocated on the roof of the nasal cavity. These small organs are coated with a thick layer of mproduced by the olfactory glands. The aromatic molecules diffuse through this mucus and bindreceptor in the numerous olfactory cilia. These cilia are extensions of modified neurons caolfactory receptor cells.Once the aromatic molecule binds to the receptor, it triggers a nervous impulse in the olfac

receptor cell. As this impulse travels along the cell, it passes through the olfactory foramen incribriform plate of the ethmoid. Then it reaches the olfactory bulb, which isthe terminal portiothe first cranial nerve. Within the olfactory bulb, the olfactory receptor cell formssynaptic connectiwith other neurons. The impulse is transferred to these neurons and continues down the olfactract. Finally, the impulses are carried to the appropriate olfactory interpretation areas in the brThese include regions in both the frontal and the temporal lobes of the cerebrum.

K e v t o I ll u s tr a t i o n1. Olfactory bulb2. Olfactory tract3. Olfactory receptor cells

(neurons)

4. Supporting cells5. Olfactory foramen6. Cribriform plate of ethmoid7. Olfactory gland

8. Lamina propria9. Olfactory epithelium10. Mucous layer11. Olfactory cil ia __

~ - - - - - - - - - - - - - - - - - - - - - - - - ---- ---- - - - - - - - - - - - - - -


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S P E C I A L S E N S E S -O l f a c t i o n

4 -_-'-3

oo

Frontalsinus1

Opening tonasal cavity

Sen se of S

7 Neuron

Note:Large arrowsindicatedirectionof nervousimpulse.

Pituitary

Palatine processof maxilla Note: Small arrowsindicate direction

of airflow.1. _2. _3. _4. _5. _6. _7. -- _8. _9. _10. _11. _

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N o t e s

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