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A&P Winter > 17. Special Sences > Flashcards

17. Special Sences Flashcards

1
Q

Special Senses

A

• vision, hearing and equilibrium
-complex sensory organs (eye/ear)

• smell and taste
- distinct epithelial structures (olfactory epithelium + taste buds)

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2
Q

What’s unique about sense of smell and taste

A
  • chemical senses
  • sensory receptors that interact with molecules dissolved in aqueous solution
  • complement each other
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3
Q

What are the receptors for smell, where are they found?

A

bipolar neurons in epithelium on roof of nasal cavity

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4
Q

how do we smell?

A

Odorants dissolve in mucous epithelium and olfactory hairs on the dendrites respond to the chemical stimulus via a receptor protein
~ longer version ~

  • olfactory hairs (~10-12 cilia) extend from dendrite of olfactory receptor and are embedded in mucus layer
  • mucus dissolves odor molecules in incoming air
  • dissolved odor binds to receptor protein  opens Na+ channels  generates action potential
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5
Q

Thalamus is relay station of special spences EXCEPT

A

the sense of smell.

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6
Q

Pathway to brain for smell

A

Axons of olfactory nerves –>ethmoid bone –>I. olfactory bulb –> olfactory tract –> primary olfactory cortex (temporal lobe)

Pathway to frontal lobe: smells interpreted/identified
Pathway to limbic system: (“emotional” brain) associate odors with memories

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7
Q

Olfactory adaptation

  • what is it
  • why does it happen
A
  • occurs rapidly
  • only smell scents a short time, then no longer smell, even though it is still there
  • Due to closing of ion channels close after a few minutes
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8
Q

5 basic taste sensations

A

sweet, sour, salty, bitter and umami

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9
Q

Taste information pathway

A

Chemicals in food dissolve in saliva, diffuse into taste pore and contact hairs of gustatory cells –> food chemical binds to receptor on taste cell membrane → depolarizes membrane → release neurotransmitter from sensory dendrites → action potential generated

Facial nerve (VII), Glossopharyngeal nerve (IX) and Vagus (X) –>medulla –> thalamus –> Primary taste cortex (perceive taste sensation) in insula

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10
Q 
Accessory Structures of the Eye
Eyebrows
Eyelids
Conjunctiva
Extrinsic Eye Muscles
A

Eyebrows

  • Function: shades eye from sunlight
  • catches perspiration from forehead

Eyelids
- skin-covered folds
- Function: protect eye from foreign objects, excess light
spread lubricating secretions over eye
- Eyelashes - trap and sweep away foreign particles

Conjunctiva

  • transparent vascular mucous membrane
  • lines inner surfaces of the eyelids and covers anterior surface of the sclera
  • secretes mucous to prevent desiccation of the eyes

Extrinsic eye muscles

  • six skeletal muscles that originate on bony orbit and insert on sclera (white of eye)
  • Function: maintain shape of the eyeball, hold it in orbit, and provide precise eye movements
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11
Q

Sty

A

infected hair follicle at base of eyelash

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12
Q

Blood Shot Eyes

A

vessels in conjunctiva over sclera get irritated and dilated

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13
Q

Conjunctivitis

A

inflammation of the conjunctiva (by bacteria or virus)

if severe it is a highly contagious infection known as pinkeye

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14
Q

Diplopia

A

Double vision; eyeballs can’t be focused on same visual field due to paralysis, weak eye muscles, alcohol consumption

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15
Q

Strabismus

A

cross eyed; due to congenital weakness in eye muscles in which the affected eye rotates medially or laterally

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16
Q

Lacrimal (Tear) gland

A

in superior lateral region of each orbit
secretes lacrimal fluid (tears) continuously
tears contains water, salt, mucous, antibodies, and lysozyme
clears, lubricates, moistens the eye

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17
Q

Pathway of Tears

A

lacrimal gland → lacrimal ducts → lacrimal fluid flows over the eye → lacrimal punctum → lacrimal canaliculus→ lacrimal sac → nasolacrimal duct → nasal cavity

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18
Q

List the 3 tunics and their parts

A

Fibrous tunic

  • Scleara
  • Cornea

Vascular Tunic

  • Chorid
  • Ciliary Body
  • Iris

Retnia

19
Q

Fibrous tunic - outermost avascular layer

  • Scleara
  • Cornea
A

a) Sclera - posterior portion
‘white’ of the eye
Function: maintains shape of the eye, protects inner surface

b) Cornea - anterior transparent portion with a fixed curvature
Function: majority of light bending (refraction) occurs at cornea to focus light rays

20
Q

Vascular Tunic - highly vascularized middle layer

  • Chorid
  • Ciliary Body
  • Iris
A

a) Choroid - darkly pigmented region, contains many blood vessels
Function: absorbs excess light to prevent scattering (cause visual confusion) & supplies nutrients to POSTERIOR 1/3 surface of retina
(NOTE: the central artery of the retina supplies nutrients to the anterior 2/3 surface of the retina)

b) Ciliary body - muscular ring around lens
Ciliary muscles - smooth muscle that regulate the shape of the lens
Ciliary processes - folds that contain blood vessels that produce aqueous humor
Suspensory ligaments - extend from ciliary processes to hold lens in position

C) Iris - pigmented part of the eye
contains circular and radial smooth muscles
opening in iris is the pupil, where light enters the eye
Function: iris muscles adjust the pupil size

21
Q

Retnia Layers:

A
  • Pigmented layer - closest to choroid, absorbs excess light to reduce scattering
  • Neural layer - visual part of the retina, photoreceptors + bipolar + ganglion
22
Q

Retnia Photoreceptor layer

A

RODS: ~120 million dim light receptors

  • excited by low light intensity
  • produce images in shades of grey
CONES: ~6 million bright light receptors
- excited by high light intensity
- provide color vision
- 3 kinds (blue, green & red) that are sensitive to different wavelengths of light
- macula lutea = yellow flat spot on retina, contains fovea centralis
- Fovea Centralis
   > has only cones (no rods)
   > site of greatest visual acuity
23
Q

Retnia Bipolar Layer

A

BIPOLAR CELLS – ‘relay’ information from photoreceptors to ganglion cells

24
Q

Retnia Ganglion Layer

A

GANGLION CELLS – axons of these neurons converge at optic disc; form optic nerve (II)

25
Q

Cataract

A

clouding of the lens due to changes in lens proteins
Get clumping of crystalline proteins
Not enough nutrients reach deeper lens fibers

26
Q

Anterior v. Posterior cavity

A

Anterior cavity

  • located in front of the lens
  • filled with watery aqueous humor
  • Function: maintains intraocular pressure (~16-20 mmHg) to support eyeball internally
  • provides oxygen and nutrients to lens and cornea
  • Aqueous Humor forms continuously, so it has to be removed continuously Rate of Secretion = Rate of Reabsorption

Posterior cavity
- located behind the lens
- filled with gel-like vitreous humor (body)
- Function: also maintains intraocular pressure
holds the retina in place
- Vitreous Humor is formed during embryonic life and is NOT replaced!!

27
Q

What is light?

A
  • a wave of energy that radiates from the sun and travels through space at a high velocity
  • Form of electromagnetic radiation
  • Eyes are sensitive to wavelengths in the range of 400-700nm (visuble spectrum)
  • See objects because light is reflected from their surfaces (reflected light is captured by our eyes)
28
Q

4 ways to form an image on retina

A

1) Refraction
- light is refracted (bent) as it passes through media of different densities
- cornea and lens does with, with majority in cornea

2) Accommodation of lens
- changes in curvature of lens that enables you to focus on nearby objects
- close = rounder lens
- far away = little adjustment [ciliary muscle contracts for close C=C!])

3) Constriction of the pupil
- far = pupil dilates (radial smooth muscle, fax light entry)
- close = pupil constricts (circular SM)

4) Convergence of the eyes
- extrinsic eye muscles turn eyes

29
Q

Visual Nervious Pathwat

A

Light –> photoreceptor cells –> bipolar Neurons –> ganglion neurons (axons exit eye as Optic Nerve) –> Optic Chiasma (axons cross to opposite side) –>Optic Tract –> Thalamus –> Visual Sensory Area in Occipital Lobe of Cerebrum

30
Q

Conversion of image to nerve impulse

A

• photoreceptor cells contain photopigments
all photopigments contain:
• Opsin + Retinal
• 4 kinds of opsins: allow rods (1 opsin) and cones (3 opsins) to absorb different wavelengths of light
• 3 cones = red, blue & green
• “name” is colour of wavelength of light they absorb best

31
Q

Myopia V. Hyperopia

A 
1) Myopia 
• near-sighted; 
• see near, far blurry
•  eyeball long + lens curved
• image focuses in front of retina
• Correct: diverging/concave lens  (decreases refraction)
2) Hyperopia 
• far-sighted
• see far,  near blurry
•  eyeball short + lens flat
• image focuses behind the retina
• Correct: converging/convex lens (increases refraction)
32
Q

Internal Ear

A

Auricle (pinna)
- directs sound waves

External acoustic meatus

  • hairs and ceruminous glands that secrete cerumen (earwax)
  • the resonating canal for sound waves

Tympanic membrane = ear drum
- vibrates in response to sound waves

33
Q

Middle Ear

A
  • air-filled, mucosa-lined cavity in temporal bone
  • al window and round window (membrane covered openings)

Auditory Tube

  • connects to nasopharynx
  • equalize pressure in the middle ear cavity with the external air pressure

Auditory Ossicles (malleus, incus, stapes)

  • conduct and amplify vibrations from the tympanic membrane
  • stapes fits into the oval window
34
Q

Inner Ear Overview

A

Bony Labyrinth: series of canals hollowed out in bone, lined by periosteum, contains perilymph fluid

  • Vestibule
  • Semicircular Canals
  • Cochlea

Membranous Labyrinth: epithelial sacs + ducts containing endolymph

  • Utricle & saccule: Static equilibrium
  • Semicircular ducts: Dynamic equilibrium
  • Cochlear Duct : Hearing
35
Q

cochlea has 3 channels side by side:

A

i) Scala vestibuli – upper channel
- begins at oval window
- contains perilymph

ii) Cochlear duct (scala media)
- middle channel, blind-ended
- contains endolymph

iii) Scala tympani – lower channel
- ends at round window which acts like a secondary tympanic membrane to dissipate sound waves
- filled with perilymph

36
Q

What is sound

  • wave, freq, intensity
  • What does high freq/ intensity mean
  • measured in
  • diffrence percieved as
A
  • Sound travels through air as waves
  • originate from a vibrating object & compress air as it vibrates

• Frequency of sound vibration (waves/sec) is measured in hertz (Hz) –> pitch
- ↑ frequency (shorter wavelength) = higher pitch

• Intensity of sound vibration (amplitude) is measured in decibels (dB) –> loudness
- ↑ intensity (higher amplitude) = louder sounds

37
Q

Pathway of Sound and the expanded Physiology of Hearing

A

auricle–>external auditory canal –>tympanic membrane–>malleus–>incus–>stapes–>oval window–>scala vestibuli–>vestibular membrane–>cochlear duct–>basilar membrane–>organ of corti–> cochlear branch of vestibulocochlear nerve

• Auricle directs sound waves into external acoustic meatus
• Sound waves cause tympanic membrane to vibrate at same frequency and intensity as incoming sound waves
• Vibrations pass to malleus, incus and stapes (ear ossicles) and get magnified
• Ear ossicles – transmit vibrations from large surface area of eardrum into larger vibrations over a smaller surface area at oval window
• Stapes attaches to oval window and creates fluid pressure waves in the perilymph of the cochlea
> oval window moves in and out
> when oval window bulges inward it pushes on the perilymph of scala vestibuli (top most chamber of cochlea)
• Pressure waves then push against the vestibular membrane creating pressure waves in the endolymph of the cochlear duct (middle chamber of cochlea)
• Endolymph then pushes down on the basilar membrane
• Pressure waves cause the basilar membrane to vibrate
• Hair cells of the organ of Corti rest on the basilar membrane and their hairs move against the overlying tectorial membrane to generate a nerve impulse

38
Q

Organ of Corti

A
  • spiral organ
  • hearing receptor cells (cochlear hair cells) + supporting cells
  • 1 row inner hair cells – auditory info sent to the brain
  • 3 rows outer hair cells – enhance response of inner cells to sound intensity and pitch
39
Q

Hair Cells

  • What’s the long projections on top of the hair cells
  • What happens when they bend
  • Nerve Impulse Pathway
A

Stereocilia: at tip of hair cells, arranged in rows, dif heights, embedded in tectorial membrane

Hair Cells Bend:
> due to sound pressure wave hitting basilar membrane
> generates a nerve impulse
> hairs bend toward the tallest stereocilium
> open K+ channels –> opens Ca2+ channels
> hair cell depolarize
> increase of Ca2+ –> increases release of GLUTAMATE

• Nerve impulse conducted to the cerebral cortex:
cochlear branch of Vestibulocochlear nerve VIII → medulla → midbrain → thalamus → primary auditory area in temporal lobe

40
Q

How do we determine: Pitch? Loudness?

A

To determine pitch:

  • each section of basilar membrane is tuned for a specific pitch
  • High freq sounds: increase vibrations at base = high pitch
  • Low freq sounds: increase vibrations at apex = low pitch
Determine Loudness:
↑ movement of tympanic membrane
↑ pressure waves
↑ movements of hair cells
↑ release of neurotransmitter
↑ frequency of action potentials
Detect a LOUDER sound
41
Q

Static Equilibrium

A
  • control of the position of the head with respect to gravity and linear acceleration
  • saccule and utricle
  • supporting cell = contain macula
  • embedded in otolithic membrane
  • can detect BOTH side to side and up/down movements
42
Q

Dynamic Equilibrium

A
  • control of the position of the head during rotational movements
  • semicircular duct
  • supporting cell = crista in the ampulla
  • embedded in cupula
43
Q

Summary: How do we dectect Hearing, Static and Dynamic Equilibrium

  • Bony Labyrinth
  • Membranous Labyrinth
  • Hair cells and supporting cell structure?
  • Hairs embedded in?
A 
HEARING
BL: cochlea
ML: cochlear duct
Hair Cell/Supporting:  Organ of corti on basilar membrane
Embedded:  Tectorial membrane
STATIC
EQUILIBRIUM
BL:vestibule
ML: utricle & saccule
Hair Cell/Supporting: macula
Embedded:  Otolithic membrane
DYNAMIC EQUILIBRIUM
BL: Semi- circular canals
ML: Semi-circular ducts
Hair Cell/Supporting: crista
Embedded:  cupula

A&P Winter (10 decks)

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