Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL1191 > Chapter 17 - Special Senses > Flashcards

Chapter 17 - Special Senses Flashcards

1
Q

Olfaction

A

The sense of smell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Olfactory Epithelium

A

Epithelial cells found in the roof of the nasal cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

3 Cell Types Found in Olfactory Epithelium

A
  1. Supporting (Sustentacular) Cells
  2. Basal (Stem) Cells
  3. Olfactory Receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Supporting (Sustantecular) Cells

A

Provide support, insulation, nourishment, and detoxification to the olfactory epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Basal (Stem) Cells

A

Layer that constantly divides to form new olfactory/gustatory receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Olfactory Receptors

A
  • Pseudostratified bipolar sensory neurons sensitive to odorants
  • Have 1 olfactory hair + 1 unmyelinated axon
  • Bowman’s Glands = secrete mucous
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Olfactory Transduction (6 Steps)

A
  1. Odorant binds to receptors on olfactory hairs
  2. G-protein linked activation of adenyl cyclase
  3. cAMP activation
  4. Na+ influx
  5. Generator potential
  6. Action potential
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Olfactory Pathway

A

Olfactory receptors -> RIght & left olfactory nerves (penetrates cribiform plate) -> Olfactory bulbs (synapses w/ 2nd order relay neurons) -> Olfactory tracts -> Primary olfactory area

  • Projections to limbic system & hypothalamus = visceral/emotional responses to smell & memory evoked responses
  • Projection to thalamus = odor identification & discrimination area of frontal lobe
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Primary Odors

A
  • Hundreds in total
  • Nose can recognize approx. 10,000 different odor combinations
  • 10 to 100 million olfactory receptors present in epithelium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Odor Thresholds & Adaptation

A
  • Smell threshold may be very low
  • Adaptation to odors occurs quickly
  • With age, decreased olfactory receptor no. = hyposmia/ anosmia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Gustation

A

The sense of taste

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

5 Primary Taste Sensations

A
  1. Bitter
  2. Sour
  3. Salty
  4. Sweet
  5. Savory (Umami)
    * Complex flavors = combinations of primary tastes + smell + tactile sensations
    * Lowest sensitivity threshold = bitter
    * Highest sensitivity threshold = savory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Adaptation

A

Decreased sensitivity due to constant stimulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Tastants

A

Chemical substances that cause gustatory (taste bud) stimulation, as well as olfactory stimulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Odorants

A

Chemical substances that cause olfactory stimulation, also affects gustation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

3 Types of Epithelial Cells in Taste Buds

A
  1. Basal (Stem) Cells
  2. Supporting Cells
  3. Gustatory Receptors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Supporting Cells (Gustatory)

A

Provide nutritional support to other cells in taste buds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Gustatory Receptors

A

Have 1 gustatory hair (microvillus) which project from the taste pore which synapses w/ the 1st order sensory neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Taste Transduction (Ionic Tastes)

A

Dissolved tastants bind gustatory hairs -> Salty (Na+) and Sour (H+) enter cell via ion channels of different gustatory receptors -> Ca+2 influx -> Exocytotic release of neurotransmitter -> EPSPs in 1st order sensory neuron -> Firing of action potentials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Taste Transduction (Organic Tastes)

A

Dissolved tastants bind gustatory hairs -> Sweet, bitter, umami bind surface protein receptors of different gustatory receptors -> 2nd messenger release -> Closing of K+ channels, depolarizing cell -> Ca+2 influx + release of stored ER Ca+2 -> Increased cytosolic Ca+2 -> Exocytotic release of neurotransmitter -> EPSPS -> Action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

4 Different Locations of Taste Buds

A
  1. Tongue
  2. Soft Palate
  3. Pharynx
  4. Epiglottis
    * More taste buds associated w/ lingual papillae, located on dorsal/lateral tongue surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

4 Papillae Types

A
  1. Vallate Papillae
  2. Fungiform Papillae
  3. Foliate Papillae
  4. Filiform Papillae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Vallate Papillae

A

V-shaped row near back of tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Fungiform Papillae

A

Scattered over dorsal tongue surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Foliate Papillae

A

Located on sides of tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Filiform Papillae

A

Most numerous on tongue; no taste buds, contain tactile receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Gustatory Pathway

A

Cranial nerves 7, 9, & 10 carry taste info -> Gustatory nucleus in medulla (synapse w/ 2nd order relay neurons) -> Limbic system & hypothalamus (emotional response) + Thalamus -> Primary gustatory area of parietal lobe & nearby association areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

3 Different Accessory Structures of the Eye

A
  1. Extrinsic Muscles
  2. Eyelids + Eyelashes
  3. Lacrimal Apparatus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

3 Pairs of Extrinsic Eye Muscles

A
  1. Superior + Inferior Rectus: Elevation + Depression of eyeball
  2. Lateral + Medial Rectus: Abduction + Adduction of eyeball
  3. Superior + Inferior Oblique: Intorsion + Extorsion of eyeball
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

3 Cranial Nerves that Control Extrinsic Eye Muscles

A
  1. Oculomotor (3) nerve
  2. Trochlear (4) nerve
  3. Abducens (6) nerve
    * Brainstem & cerebellum control eyeball movements
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Functions of the eyelids

A

To provide shade, protection & lubrication to the eyball

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Surface Anatomy of Eyelid (3 Parts)

A
  1. Palpebral Fissure = Space between upper & lower eyelids
  2. Lateral & Medial Commisures = Corners where the upper & lower eyelids meet
  3. Lacrimal Caruncle = Small, pink, globular nodule at the corner of the eyeball
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Palpebral Layers of the Eyelid

A
  1. Epidermis
  2. Dermis
  3. SubQ tissue
  4. Orbicularis oculi
  5. Tarsal plate
  6. Tarsal gland
  7. Tarsal plate
  8. Areolar CT
  9. Palpebral conjunctiva
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

2 Eyelid Muscles

A
  1. Orbiculars Oculi = Closes eyelids

2. Levator Palpebrae Superioris = Opens eyelids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Tarsal Glands

A
  • Embedded in tarsal plate

- Responsible for lipid-rich secretions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Chalazion

A

Cyst in the eyelid due to a blocked oil gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

2 Types of Conjuctiva

A
  1. Palpebral = Continuous w/ Bulbar Conjunctiva
  2. Bulbar Conjunctiva = Covers sclera, but not cornea
    * Blood shot eyes caused by vasodilation due to irritation of bulbar conjunctiva
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Eyelashes

A
  • Blink reflex allows eyelashes to brush off dirt
  • Sebaceous ciliary glands secrete oil which lubricates the eyes
  • Sty = infection of sebaceous ciliary glands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

2 Parts of the Lacrimal Apparatus

A
  1. Lacrimal Gland + Excretory Lacrimal Ducts

2. Lacrimal Sac + Superior & Inferior Lacrimal Canaliculi + Nasolacrimal Duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Lacrimal Gland

A
  • Secretes fluid (tears), contains salt, mucus & lysozyme
  • Functions to protecct, clean & lubricate the eyes
  • Parasympathetic innervation via Facial (7) nerve
  • Tears -> Lacrimal puncta -> Superior & inferior lacrimal canaliculi -> Lacrimal Sac -> Nasolacrimal duct -> Nose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Dacrocystitis

A

Infection of the lacrimal sac; usually bacterial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

3 Coats (Tunics) of the Eyeball

A
  1. Fibrous Tunic
  2. Vascular Tunic
  3. Retina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Fibrous Tunic (2 Main Parts)

A
  1. Sclera

2. Cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Sclera

A

White, dense CT, surrounds eyeball except at cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Cornea

A

Transparent cover over iris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Canal of Schlemm (AKA “Scleral Venous SInus”)

A

Drains aqueous humor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Vascular Tunic/Uvea (3 Main Parts)

A
  1. Choroid
  2. Ciliary Body
  3. Iris
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Choroid

A
  • Middle, dark brown layer of vascular tunic
  • Has many blood vessels
  • Absorbs stray light
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Ciliary Body

A
  • Runs from ora serrata to corneal/scleral junction
  • Contains ciliary muscle (controls shape of lens)
  • Ciliary process -> Aqueous humor & attach zonular fibers
  • Accommodation for near vision = contraction of ciliary muscle; leads to decreased tension on zonular fibers, which leads to rounding up of lens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Iris

A
  • Circular pigmented diaphragm, which regulates size of pupil
  • Eye color = type & amount of melanin
  • Eumelanin = black-brown pigment
  • Pheomelanin = reddish-yellow pigment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

2 Pupillary Responses to Light Intensity

A
  1. Miosis

2. Mydriasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Miosis

A

Contraction of sphincter pupillae due to bright light (Parasympathetic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Mydriasis

A

Contraction of dilator pupillae due to dim light (Sympathetic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Retina/Inner Tunic (2 Layers)

A
  1. Pigmented Layer

2. Neural Layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Pigmented Layer

A

Contains melanin

*Ocular melanoma = Eye cancer

56
Q

Neural Layer (3 Parts)

A
  1. Photoreceptor Layer
  2. Bipolar Cell Layer
  3. Ganglion Cell Layer
57
Q

Photoreceptor Layer

A

Contains rods & cones

58
Q

Bipolar Cell Layer

A

Contains bipolar neurons

59
Q

Ganglion Cell Layer

A

Contains ganglion cells whose fibers -> Optic (2) nerve

60
Q

Outer Synaptic Zone

A

Area between photoreceptor & bipolar layer

61
Q

Inner Synaptic Zone

A

Area between bipolar & ganglion cell layer

62
Q

2 Photoreceptors Found in Retina

A
  1. Rods
  2. Cones
  • Both contain light-sensitive pigments
  • Light striking photoreceptors permits bipolar cells to stimulate ganglion cells to fire APs along their axons, which form the optic (2) nerve.
63
Q

Rods

A
  • Photoreceptors for low illumination (i.e. night vision)
  • Cause mydriasis in dim light
  • Only rods (located in periphery of retinae) are sensitive to faint light
  • Do not detect fine detail/color
  • Very sensitive in low illumination
  • High neural convergence = electrical activity of many rods converges on a single ganglion cell
64
Q

Cones

A
  • Photoreceptors reponsible for color vision & visual acuity
  • Outer segment is cone-like
  • Cone photopigment = iodopsin = cis-retinal + different opsin
  • 3 Types: Blue, red & green; respond to different wavelengths of light
  • Perception of many colors = mixing inputs of 3 different cone types
  • Most visual images are focused on fovea centralis
65
Q

2 Other Retinal Cell Types

A
  1. Horizontal Cells
  2. Amacrine Cells

*Both modify passing signals between the 3 cell layers

66
Q

Neural Cell Convergence

A
  • 120 mil. rods/retina & 6 mil. cones/retina, but only 1 mil. ganglion cells
  • Up to 600 rods synapse w/ each bipolar cell (Leads to high sensitivity w/ poor resolution)
  • 1 cone synapses w/ each bipolar cell (Leads to low sensitivity w/ high resolution)

*Signal integration occurs before APs sent to lateral geniculate nucleus of thalamus & then to primary visual area of occipital lobes

67
Q

Optic Disc

A
  • AKA “Blind Spot”

- Space where optic nerve & central retinal artery & vein pass through retina

68
Q

Ophthalmoscope

A

Device used to examine the eye grounds

69
Q

Macula Lutea

A
  • Oval, yellowish retinal area w/ depression (Fovea Centralis)
  • Fovea Centralis has the highest resolution
  • Visual acuity/Resolution = due to greatest concentration of cones
70
Q

Age-related Macular Disease (2 Types)

A
  • Defined as gaps in central vision (Causes distortion of images)
    1. Dry form: Pigment layer atophy
    2. Wet form: Leaky blood vessels, progression of dry form
71
Q

Retinal Detachment

A
  • Caused by accumulation of fluid between retina & choroid
  • Treatment: Pneumatic retinopexy or scleral buckle
72
Q

Interior of Eyeball (2 Parts)

A
  1. Crystalline Lens

2. Anterior & Posterior Cavities

73
Q

Crystalline Lens

A
  • Attached to ciliary processes by zonular fibers (suspensory ligaments)
  • Composed of crystallin protein, arranged in laminae
74
Q

Cataracts

A

Opacity in lens, causing blurred vision

75
Q

Posterior Cavity

A
  • AKA “Vitreous Chamber”
  • Filled w/ vitreous humor (AKA “Vitreous Body”)
  • Vitreal Floaters = Small spots that drift throught the field of vision
  • Hyaloid Canal = Site of hyaloid artery
76
Q

Anterior Cavity

A
  • Located between cornea & lens
  • Subdivided into anterior & posterior chambers
  • Filled w/ aqueous humor made by ciliary processes
77
Q

Intraocular Pressure

A
  • Fluid pressure inside the eye
  • Normal range = 12 -22 mmHg
  • Average = 16 mmHg
78
Q

Glaucoma

A
  • Increased intraocular pressure due to blockage of canal of Schlemm/scleral venous sinus; causes compression of renal areries
  • Can lead to ischemic damage, which can cause partial/complete blindness
79
Q

Visible Light

A

Wavelengths of electromagnetic spectrum (400 - 700 nanometers)

*Vision = Presence of retinal photoreceptors capable of recording these energy wavelengths

80
Q

Refraction of Light Rays

A
  • Bending of light as it passes from one translucent medium to another of different density
  • Concave surfaces cause light to bend outward/diverge
  • Convex surfaces cause light to bend inward/converge
  • Converging light rays meet at the focal point
  • Images on retina inverted & reversed
  • Eye parts that refract light: cornea, aqueous humor, lens, vitreous humor
81
Q

Changing Shape of Lens (2 Ways)

A
  1. Flattening = Relaxation of ciliary muscles, increasing tension on zonular fibers (For far vision)
  2. Rounding = Contraction of ciliary muscles, decreasing tension on zonular fibers (For near vision)
82
Q

Accommodation

A

Contraction of ciliary muscles to enable near vision

83
Q

Near Point of Vision

A
  • Minimum distance from eye that an object can be clearly focused
  • Changes w/ age due to decreased lens elasticity
84
Q

Presbyopia

A

Loss of lens elasticity due to advancing age

85
Q

3 Processes of Image Formation on Retina

A
  1. Light refraction by cornea & lens
  2. Accommodation of lens, for near vision
  3. Constriction of pupil to prevent extraneous light from entering eye

*Functions 2 & 3 result parasympathetic motor innervation -> contraction of intrinsic eye muscles

86
Q

Convergence (Other Meaning)

A

Medial movement of eyeballs to a single image of near object

87
Q

3 Types of Refraction Abnormalities

A
  1. Myopia
  2. Hyperopia
  3. Astigmatism
88
Q

Emmetropia

A

Normal vision

89
Q

Myopia

A
  • Nearsightedness; only near objects can be seen clearly
  • Causes: Focus isn’t directed to retinal screen, but vitreous humor
  • Treatment: Concave corrective lens
90
Q

Hyperopia

A
  • Farsightedness; only far objects can be seen clearly
  • Causes: Focus goes farther than the retinal screen
  • Treatment: Convex corrective lenses
91
Q

Astigmatism

A

Irregular curvature of lens/cornea

92
Q

Mechanism for Light Transduction

A
  • Rod outer segment = Disc-like membrane stacks w/ embedded rhodopsin
  • Light splits rhodopsin into retinal & opsin (called bleaching)
  • Cis -> trans isomerization causes trans-retinal to seperate from opsin
  • Isomerization step -> chemical reactions-> receptor potential
  • Retinal isomerase converts trans-retinal -> cis-retinal which re-associates w/ opsin (called regeneration)
93
Q

Isomerization Process

A

Activation of an enzyme (PDE) that degrades c-GMP -> Closes c-GMP-gated Na+ channels -> Decreased Na+ influx (dark current) -> Hyperpolarizing receptor potential -> Cessation of tonic glutamate inhibitory neurotransmitter release

*Permits EPSPs in bipolar neuron -> activation of amacrine cell -> firing action potentials by ganglion cell axon

94
Q

Regeneration Process

A

Retinal Isomerase converts trans-retinal -> cis-form, which re-attaches opsin -> Inhibition of PDE -> c-GMP accumulation in rod cell -> Re-opening of c-GMP- gated Na+ channel -> Na+ influx -> Membrane depolarization -> Tonic glutamate inhibitory neurotransmitter release (Which prevents activation of bipolar neuron due to IPSPs causing hyperpolarization)

95
Q

Retinal

A
  • Vitamin A derivative

- Vitamin A found in vegetables w/ carotenes, such as carrots

96
Q

Light Adaptation

A
  • Rods switch “off” due to decreased rhodopsin & cones switch “on”
  • In strong light, rod bleaching is much faster than regeneration
  • Rods hardly contribute to visual signal
  • Cones do contribute to visual signal, because they cycle faster
  • Rapid regeneration in strong light happens because some photopigment in cones always in cis-form
  • Bright lights cause miosis, which also reduces rod participation
97
Q

Dark Adaptation

A
  • Rods switch “on” & cones switch “off”
  • Takes several minutes due to need to synthesize more rhodopsin
  • Cones insensitive to weak light
  • Dim lights cause mydriasis, which also increases rod participation
98
Q

Color Blindness

A
  • Condition caused by deficiency in a particular cone type

- Red-green color blindness: Red & green are seen as the same color

99
Q

Nyctalopia

A
  • “Night Blindness”

- Caused by chronic vitamin A deficiency

100
Q

Visual Pathway

A

Ganglion cell action potentials -> Optic (2) nerve -> Optic chiasm -> Optic tract -> Lateral geniculate nucleus of thalamus -> Optic radiations -> Primary visual area

101
Q

Stereoscopic (AKA “Binocular”) Vision

A
  • Each eye sends info to brain about object, but from a slightly different angle
  • Integration of the signals -> steroscopic vision
102
Q

Depth Perception

A

Ability to perceive relative distance of objects in a visual field

103
Q

2 Steps of Stereoscopic Vision

A
  1. Since optic nerves cross at optic chiasm, each half of brain receives info from both eyes about same part of an object
    - 1a. Neurons carrying info about the nasal visual field of one eye & temporal visual field of opposite eye project to the same cerebral hemisphere
    - 1b. Axons from two medial halves of the retinae cross in optic chiasm
    - 1c. Axons from two lateral halves of the retinae remain uncrossed
  2. Two halves of the brain communicate -> 3D interpretation of object
104
Q

2 Locations Ganglion Cell Axons Travel To

A
  1. Midbrain
    - 1a. Pretectal Nuclei: Pupillary accommodation reflexes
    - 1b. Superior Colliculi: Head + eye movements regarding sight sound
  2. Suprachiasmatic Nucleus (Circadian Rhythm)
105
Q

2 Sensory Functions Located in Inner Ear

A
  1. Equilibrium (AKA “Balance”)
  2. Hearing (AKA “Audition”)

*Mechanoreceptors = hair cells w/ stereocilia that respond to mechanical stimulation

106
Q

3 Major Parts of the Ear

A
  1. External (Outer) Ear
  2. Middle Ear
  3. Internal (Inner) Ear
107
Q

External (Outer) Ear (3 Parts)

A
  1. Auricle (AKA “Pinna”): Consists of helix & lobule
  2. External Auditory Canal: Lined w/ epidermis & derivatives (fine hairs, sweat glands & ceruminous glands)
  3. Tympanic Membrane: The eardrum
108
Q

Middle Ear

A
  • Space within temporal bones
  • Begins just medial to tympanic membrane
  • Extends to bony wall w/ oval window & round window
  • Opening duct leads to mastoid sinuses
109
Q

3 Auditory Ossicles in Middle Ear

A
  1. Malleus (Hammer)
  2. Incus (Anvil)
  3. Stapes (Stirrup)
    - Footplate rests on oval window’s membrane
110
Q

Otitis Media

A

Infections of the middle ear

111
Q

Auditory (Eustachian) Tube

A
  • Runs from middle ear to nasopharynx
  • Equalizes air pressure on both eardrum surfaces
  • Ensures sound waves striking eardrum are not attenuated
112
Q

Protection Against Loud Noises (2 Ways)

A
  1. Tensor Tympani muscle contraction = Decreased motion of eardrum
  2. Stapedius muscle contraction = Decreased motion of stapes
113
Q

Hyperacusia

A
  • Abnormally sensitive hearing

- Caused by paralysis of either the tensor tympani, or stapedius or both

114
Q

Internal (Inner) Ear (2 Divisions)

A
  1. Bony Labyrinth: Contains perilymph

2. Membranous Labyrinth: Contains endolymph

115
Q

3 Main Components of the Inner Ear

A
  1. Vestibule
  2. Semicircular Canals
  3. Cochlea
116
Q

Vestibule

A
  • Chamber between semicircular canals & cochlea
  • Function: Maintain static balance
  • Contains the utricle & saccule
  • Mechanoreceptors contained in the macula of the utricle & saccule
  • Stereocilia of hair cells stick to gelatinous otolithic membrane
  • Mechanoreceptors provide info on position of head + linear acceleration/deceleration
117
Q

Otoliths

A
  • CaCO3 granules located on the utricle & saccule
  • Embedded on top of otolithic membrane
  • Motion -> sagging of otolithic membrane -> bending of hair cell’s stereocilia
118
Q

Semicircular Canals

A
  • Found in anterior, posterior & lateral forms
  • Function: Maintain dynamic balance
  • Semicircular Ducts: Inner portion of the canals
  • Ampulla: Swellings of the semicircular ducts
  • Stereocilia of hair cells stick to gelatinous cupula (which are located within the ampullae)
  • Crista: Contains supporting + hair cells for dynamic balance
  • Vestibular branch of vestibulocochlear (8) nerve is composed of ampullary nerves, utricular nerve & saccular nerve
119
Q

Cochlea

A
  • Function: Conduct hearing
  • Spirals around modiolus
  • Contains organ of Corti, which -> info to cohclear nuclei of medulla via cochlear branch of cranial nerve 8 -> thalamus -> temporal lobe
120
Q

3 Channels of the Cochlea

A
  1. Cochlear Duct (AKA “Scala Media”): Found in membranous labyrinth
  2. Vestibular Canal (AKA “Scala Vestibule”): Found in bony labyrinth
  3. Tympanic Canal (AKA “Scala Tympani”): Also found in bony labyrinth
121
Q

Organ of Corti

A
  • AKA “Spiral Organ”
  • Sends info to cochlear nuclei of medulla via cochlear branch of cranial nerve 8 -> thalamus -> temporal lobe
  • Basilar Membrane = Lower wall of cochlear duct
  • Vestibular Membrane = Upper wall of cochlear duct
  • Hair cells of the tectorial membrane rest on the basilar membrane
  • Inner hair cells (90-95% sensory) = Transduce sound vibrations into electrical impulses
  • Outer hair cells (90% motor) = Regulate sensitivity of inner hair cells
122
Q

Dynamic Equilibrium

A
  • Maintenance of body position in response to angular/rotational movement
  • Sense organs = cristae in ampullae of 3 semicircular ducts
  • During movement, endolymph within semicircular ducts displaces cupulas causing stereocilia of hair cells to bend, initiating APs in 1st order sensory neurons, which -> brain
123
Q

Transduction for Mechanical Vibrations into APs

A
  1. Hair cell’s stereocilia membrane has mechanically-gated K+ channel
  2. Bending of stereocilia in one direction -> tip-link protein opens mechanically-gated K+ transduction channel -> K+ influx -> depolarization of hair cell
  3. Hair cell depolarization -> opening of voltage-gated Ca+2 channels -> Ca+2 influx -> exocytotic release of neurotransmitter by hair cell -> EPSPs in 1st order sensory neuron -> increased AP firing rate of 1st order neuron -> brain via vestibular branch of cranial nerve 8
  4. When stereocilia are bent in the opposite direction -> closing of K+ transduction channel -> decreased AP firing by 1st order sensory neuron
124
Q

Static Equilibrium

A
  • Maintain orientation of body relative to gravity
  • Necessary for posture & balance
  • Sense organs = maculae of utricle & saccule
125
Q

Kinocilium

A

A true cilium, present in stereocilium hair bundles of mechanoreceptors for both static & dynamic balance

126
Q

Vestibular Ganglion

A

Contains cell bodies of 1st order sensory neurons (for hearing + equilibrium)

127
Q

Vestibular Nuclei

A
  • Termination point of most vestibular branch fibers of cranial nerve 8
  • Sends motor commands to cranial nerve nuclei 3, 4, 6, and 11 (coordinates eye + head movement)
  • Also sends motor commands to vestibulospinal tract (regulates muscle tone)
  • Conveys sensory info to ventral posterior nucleus of thalamus, then -> vestibular area of somatosensory cortex
128
Q

2 Characteristics of Sound

A
  1. Intensity of Vibration (AKA “Amplitude”/”Loudness”); measured in decibels (dB)
  2. Frequency of Vibration (AKA “Pitch”); audible range = 20 -20,000 Hertz
129
Q

Audition

A
  • AKA “Hearing”
  • Cochlear hair cells register a sound’s intensity & frequency
  • Sound waves strike eardrum -> vibrations conveyed to ossicles
  • Ossicles convey vibrations to oval window membrane
  • Vibrations of oval window membrane -> pressure waves in perilymph of vestibular canal
  • Loudness = Distance of eardrum travel
  • Pitch = Speed of vibration
130
Q

Helicotrema

A

Connection between the vestibular canal and tympanic canal

131
Q

Oval Window Membrane Vibration

A
  • Causes pressure waves toward round window

- When oval window membrane moves inward, round window membrane moves outward to prevent sound attentuation

132
Q

Perilymph Fluid Movement

A
  • Causes up & down movement of vestibular membrane at certain points (depending on sound frequency) -> increases pressure in endolymph in cochlear duct -> vibration of basilar membrane
  • Some stereocilia of hair cells pushed against tectorial membrane -> bending -> receptor potential -> neurotransmitter release -> EPSPs in 1st order sensory neurons -> APs
  • Cell bodies of 1st order sensory neurons in spiral organ/organ of Corti
  • APs carried by cochlear branch of cranial nerve 8 -> brainstem
133
Q

Recognition of Sound Intensity

A

The higher the sound intensity, the larger the vibrations, the greater number of APs fired per second

134
Q

Recognition of Sound Frequency

A
  • High pitch sounds cause the vestibular & basilar membranes to resonate near to oval window
  • Low pitch sounds cause the vestibular & basilar membranes to resonate near to helicotrema
  • Intermediate pitch sounds are registered at intermediate positions along the length of the organ of Corti
135
Q

Otoacoustic Emission

A
  • Motor neuron stimulation of outer hair cells -> rhythmic shortening/lengthening of hair cells -> oscillation of basilar membrane -> increased signal by inner hair cells
  • Diagnosis of deafness in newborn
136
Q

Cochlear Implants

A

Devices that translate sounds into electrical signals for interpretation by the brain; meant to help deaf people w/ destroyed hair cells

137
Q

Meniere’s Disease

A
  • Increased endolymph in membranous labyrinth
  • Endolymphatic sac maintains cosntant pressure & volume of endolymph
  • Causes tinnitus, vertigo & possible deafness

BIOL1191 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions