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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
Cataract
clouding of the lens due to changes in lens proteins Get clumping of crystalline proteins Not enough nutrients reach deeper lens fibers
26
Anterior v. Posterior cavity
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
What is light?
* 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
4 ways to form an image on retina
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
Visual Nervious Pathwat
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
Conversion of image to nerve impulse
• 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
Myopia V. Hyperopia
``` 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
Internal Ear
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
Middle Ear
* 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
Inner Ear Overview
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
cochlea has 3 channels side by side:
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
What is sound - wave, freq, intensity - What does high freq/ intensity mean - measured in - diffrence percieved as
* 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
Pathway of Sound and the expanded Physiology of Hearing
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
Organ of Corti
* 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
Hair Cells - What's the long projections on top of the hair cells - What happens when they bend - Nerve Impulse Pathway
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
How do we determine: Pitch? Loudness?
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
Static Equilibrium
* 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
Dynamic Equilibrium
* control of the position of the head during rotational movements * semicircular duct * supporting cell = crista in the ampulla * embedded in cupula
43
Summary: How do we dectect Hearing, Static and Dynamic Equilibrium - Bony Labyrinth - Membranous Labyrinth - Hair cells and supporting cell structure? - Hairs embedded in?
``` 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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