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DEN 7101S Human Structure and Function II > 1/19 Britton Special Senses I > Flashcards

1/19 Britton Special Senses I Flashcards

1
Q

What are the five special senses?

A
  • taste
  • smell
  • vision
  • hearing
  • equilibrium

HVEST

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2
Q

Taste

Sensory receptor:
Sensory organ:

A

Taste receptor; Taste bud

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3
Q

Hearing

Sensory receptor:
Sensory organ:

A
  • Hair cell
  • cochlea
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4
Q

Vision

Sensory receptor:
Sensory organ:

A
  • rods and cones
  • retina
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5
Q

Equilibrium

Sensory receptor:
Sensory organ:

A
  • hair cell
  • vestibular aparatus
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6
Q

Smell

Sensory receptor:
Sensory organ:

A
  • olfactory cell
  • olfactory epithelium
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7
Q

Gustation

A

Action of tasting

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8
Q

How many taste buds does a typical adult have

A

3,000-10,000

Children have more taste buds than adults

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9
Q

Taste buds are found on 3 types of ______ distributed on the ______ surface of the tongue

A

Papillae; dorsal surface of the tongue

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10
Q

What taste buds are found on the anterior 2/3s of the tongue

A

Fungiform

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11
Q

Where do fungiform taste buds have the highest density

A

At the tip of the tongue

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12
Q

What taste buds are large papillae arranged in a chevron (V-line) at the rear of tongue

A

Circumvallate

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13
Q

What taste buds are present on the posterolateral surface of the tongue

A

Foliate

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14
Q

Additional taste buds are found on:

A

oral mucosa of the palate, pharynx, epiglottis

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15
Q

Components of taste bud

  1. Each taste bud is composed of ______
  2. 50-100 ______
  3. numerous _____ cells and support cells
  4. all arranged around a ______ on the dorsal surface of the tongue
A
  1. epithelial cells
  2. taste cells - receptors
  3. basal cells
  4. central taste pore
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16
Q

Taste receptor is stimulated by:

A

Tastant

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17
Q

In taste buds, epithelial cells are all arranged around _____ on the _____ of the tongue

A

central taste pore; dorsal surface

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18
Q

Each taste bud is composed of:

A

Epithelial cells (taste cells/receptors, basal cells, support cells)

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19
Q
  1. _______ in the taste receptors project into the taste pore
  2. _______ provide the receptor surface for taste
  3. are exposed to _______ dissolved in saliva
A
  1. microvilli
  2. microvilli
  3. chemicals
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20
Q

How often are taste receptor cells replaced and by differentiation of what cells?

A

Every 10 days via differentiation of basal cells

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21
Q

A branching terminal network of ____ are interwoven around the taste receptor cells

A

Nerve fibers

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22
Q

Taste bud receptors are afferent or efferent?

A

Afferent sensory fibers

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23
Q

Taste receptors are modified ______ cells that respond to ______ stimuli

A

epithelial; chemical (tastants)

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24
Q

Taste receptors are _____ receptors

A

chemoreceptors

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25
Q

Taste receptors are the site of:

A

Sensory transduction

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26
Q

Taste receptors are innervated by ____ sensory nerve fibers penetrating the ______

A

afferent; basal lamina

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27
Q

Taste Bud Innervation

  1. the nerve fibers branch extensively and receive synaptic input from the ______ receptors
  2. each taste bud is innervated by how many sensory nerve fibers?
  3. each nerve fiber receives Input from how many taste buds?
A

1) Taste receptors
2) 50 sensory nerve fibers
3) 5 taste buds

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28
Q

What are the 5 different taste modalities?

A
  • sweet
  • salty
  • bitter
  • sour
  • umami
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29
Q

What is the common stimulus for sweet sensation?

A

Sucrose

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30
Q

What is the common stimulus for salty sensation?

A

NaCl

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31
Q

What is the common stimulus for sour sensation?

A

Acid

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32
Q

What is the common stimulus for bitter sensation?

A

Quinine

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33
Q

What is the common stimulus for umami sensation?

A

Monosodium glutamate (MSG)

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34
Q

What do salty and sour chemicals activate what channel?

A

Ligand gated channels

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35
Q

Salt is sensed by _____ ions
sour taste is triggered by ______
mediated via _______

A

Na+ ions; protons (H+ ions); epithelial sodium channel (ENaC)

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36
Q

Sweet, Bitter, and Umami chemicals activate what channel?

A

GPCR’s

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37
Q

Sweet sensation activates _____

A

T1R family (GPCR)

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38
Q

Bitter activates ______ (GPCR)

A

T2R family

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39
Q

_____ is coupled to a Gs protein, called ______

A

T2R; gustducin

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40
Q

Umami activates _____ (GPCR)

A

Glutamate receptor (mGluR4)

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41
Q

When stimulated, each of the taste receptor ion channels/GPCRs generate a:

A

Receptor potential

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42
Q

______ of taste receptor contains various ion channels and GPCRs

A

Apical membrane

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43
Q

Sensory Transduction in Taste Receptors

Explain the steps of sensory transduction

A
  1. Stimulation by chemical tastants
  2. Ion channel or GPCR signaling pathway generates receptor potential (depolarization)
  3. Intracellular Ca2+ increases through opening of voltage gated Ca2+ channels or release from intracellular stores
  4. Vesicles fuse to basolateral membrane for synaptic transmission (mediated by serotonin)
  5. Serotonin binds to receptors on primary sensory neurons and AP is elicited
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44
Q

What do taste receptors synapse with?
_____ from fungiform papillae
_____ from posterior 1/3 of the tongue
_____ from palate, pharynx, elsewhere

A
  • primary afferent sensory neurons (1st order) from branches of 3 cranial nerves
  • CN 7
  • CN 9
  • CN 10
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45
Q

All primary sensory nerves for taste synapse with ____ order neurons in the ____ in the _______

A

2nd; nucleus of the tractus solitarius (NTS) in the medulla

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46
Q

NTS relays information to the ______

A

Thalamus (3rd order)

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47
Q

Thalamus projects to the ______ _______

A

Gustatory cortex

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48
Q

Sensory Coding for Taste

Taste is coded in the sum of ____ in each cranial nerve in response to a specific ______

A

neural activity; taste modality

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49
Q

Each taste has its own distinct _____

A

Nerve response patterns

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50
Q

The response of different ______ and the subsequent integrations of the ______ generated encode taste

A

taste receptors; AP’s

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51
Q

Ageusia

A

Absence of taste

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52
Q

Hypogeusia

A

Diminished taste sensitivity

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53
Q

Dysgeusia

A

Unpleasant perception of taste (metallic, foul, rancid)

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54
Q

Abnormalities in taste detection can be caused by damage to what nerves?

A

CN 7 and 9 (due to neurological disorders such as Bell’s palsy, multiple sclerosis, infections)

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55
Q

Abnormalities in taste detection can be caused by ______ deficiency

A

Vitamin B3, zinc

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56
Q

Problems in taste detection can be caused by ______ (4)

A
  • poor oral hygiene
  • adverse side effect of drugs which cause xerostomia
  • aging
  • tobacco use
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57
Q

Olfactory epithelium is a specialized portion of:

A

Nasal mucosa

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58
Q

What are the 3 structures of the olfactory epithelium?

A
  • olfactory sensory neurons
  • supporting columnar cells
  • basal stem cells
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59
Q
  1. OSN’s are the ____ receptors for olfactory ____
  2. Each OSN is a _ nerve cell
  3. Each OSN projects a ________ which terminates in ____ into the mucus layer of the nasal cavity epithelium
  4. What are present on the cilia?
  5. OSN axons pass through the ____ to the ____
A
  1. sensory, transduction
  2. bipolar
  3. dendrite, olfactory cilia
  4. membrane odorant receptors (GPCR’s)
  5. cribriform plate, olfactory bulb
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60
Q

Supporting columnar cells secrete _____ that proves the appropriate environment for ____ detection

A

Mucus; odor

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61
Q

______ generate new olfactory sensory neurons as needed

A

Basal stem cells

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62
Q

Structure of the Olfactory Bulb
1. _____ are primary sensory afferents (1st order)
2. the _____ is the site where OSN synapse with dendrites of ____
3. _____ cells are 2nd order sensory neurons whose axons enter the olfactory tract and (ascend/ descend) to the olfactory cortex

A
  1. Olfactory sensory nerves
  2. glomerulus, mitral cells
  3. mitral cells-ascend (synapse with 3rd order to gustatory center in brain)
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63
Q
  1. there are _______ human genes for olfactory receptors= 3% of the human genome
  2. the olfactory system is an extremely discriminative and sensitive _______ system
  3. # of distinct odors
A
  1. 1000, olfactory
  2. chemosensory system
  3. > 1 million
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64
Q

All olfactory receptors are _____

A

G-Protein Coupled Receptors (GPCR’s)

65
Q

What is a smell?

A

Chemical in the air dissolved in the mucus

66
Q

Perceiving an odor begins with the _______ and transport of ______ to the olfactory mucosa

A

Inhalation, aromas

67
Q

Odorants bind to ______ on the _____ and initiate the sensory transduction cascade, leading to generation of ______ in the sensory ______ nerve

A

GPCR’s, cilia, APs in the sensory olfactory nerve

68
Q

Sensory Transduction in Olfactory Receptors
1) odorants bind to diverse ______ which are coupled to Gs proteins called _____
2) ______ dissociate
3) Alpha subunit activates:
4) _____ acts as a second messenger to open ____ channels
5) Inward diffusion of Na+ produces a depolarization, which is a ____

A

1) GPCR’s; Golf
2) alpha, beta, and gamma subunits
3) Adenylyl cyclase to catalyze cAMP production
4) cAMP; Na+ ion channels
5) action potential

69
Q

In sensory transduction in olfactory receptors, ____ are specific to different types of odors

A

G proteins (of GPCRs)

70
Q

Sensory Transduction in Olfactory Receptors
1. Action potentials are ______ ______ depending on the concentration of ______
2. Action potentials can be ______ to produce specific patterns of activity for each stimulating odorant
3. contributes to _____ ____ of odors
4. Action potentials in the ____ are generated and propagated to synapses in the _____ within the ______

A

1) graded responses, odorants
2) summated
3) neural coding
4) olfactory nerve (CN I); glomeruli; olfactory bulb

71
Q

Sensory Transduction in Olfactory Receptors

AP frequency is proportional to:

AP can be ______ by rapidly adapting receptors

A

1) concentration of odorants
2) attenuated
-receptors have adaptation; stimulated and sustained smells will ‘switch off’ after a long exposure

72
Q

Sensory Transduction in Olfactory Receptors
1) the ______ is the site where axons of olfactory nerves synapse with numerous dendrites from ______ cells and ______ cells
2) the mechanism of _______ of olfactory neurons with mitral cells generate ______ APs
3) this complex pattern of neuronal integration _______ the various odorant molecules
4) the axons of ______ cells (2nd order neurons) enter the olfactory tract and (ascend/descend) to the olfactory cortex

A

1) glomeruli; mitral cells; tufted cells
2) convergence/divergence, subsequent
3) discriminates
4) mitral cells; ascend

73
Q

Sensory coding for smells created from activation of:

A

Multiple receptors and neurons

74
Q

Anosmia

A

Inability to smell

75
Q

Hyposmia

A

Diminished olfactory sensitivity

76
Q

Hyperosmia

A

Enhanced olfactory sensitivity (common in pregnancy)

77
Q

Dysosmia

A

Distorted sense of smell

78
Q

Causes of Abnormalities in Odor Detection can be caused by:

A

1) damage to olfactory nerves (head trauma, tumors)
2) sinus infections
3) nasal congestion
4) nasal polyps
5) poor dental hygiene

79
Q

Basic Mechanism of Vision
The eyes convert _____ energy into AP’s in the _____ nerve that are conducted to the _______ cortex, where they produce the sensation of vision

A

photon; optic; cerebral

80
Q

2 components of vision

A

Optical and neuronal

81
Q

Visual image is focused on _______ on the retina

A

Photoreceptors

82
Q

the visual component is transduced by the _______ into a pattern of ______

A

Photoreceptors; graded receptor potentials

83
Q

What are the layers of tissue present in the eye?

A

Outer layer; middle layer; inner layer

84
Q

What is the outer layer of the eye made up of

A

Sclera and cornea

85
Q

Protective white layer of the eyeball, no light can pass

A

Sclera

86
Q

Transparent anterior portion through which light rays enter the eye

A

Cornea

87
Q

What is the fluid part of the eye made up of

A

Aqueous humor and vitreous humor

88
Q

What is the middle layer of the eye made up of?

A

Iris, ciliary body, choroid

89
Q

Colored portion of the eye, in front of the lens

A

Iris

90
Q

Adjusts the refractive power of the lens

A

Ciliary body

91
Q

Nourishing vascular layer of the eye

A

Choroid

92
Q

What is the inner layer of the eye made up of

A

Retina

93
Q

Neural tissue containing photoreceptor cells, lines the posterior 2/3rds of the choroid

A

Retina

94
Q

Formation of Images on the Retina
1) light rays ______ in all directions from their source
2) light rays that reach the _____ must be focused to a point on the _____ for optimal vision

A
  1. diverge
  2. pupil, retina
95
Q

During refraction, light waves ____ as they pass through transparent materials of different densities

A

Bend

96
Q

What is the mechanism that allows the formation of focused images on the retina?

A

Refraction

97
Q

What structures in the eye allow refraction to occur?

A

cornea and lens

98
Q

Properties of Light
1) on a concave surface: light waves striking the surface ______
2) on a convex surface: light waves striking the surface ______ at a single point called the ______ ______

A

1) diverge
2) converge, focal point

99
Q

Formation of Images on the Retina
1) the cornea and lens both have ______ surfaces and help to focus light rays on the retina
2) the _______ is responsible for most of the refraction
3) however, the curvature of the _____ can be adjusted for near and far vision-termed _______

A

1) convex
2) cornea
3) lens; accomodation

100
Q

________ is the process by which the curvature of the lens is adjusted

A

accommodation (focusing)

101
Q

The lens is suspended by ______ _____ extending from _______ that control tension on the lens

A

Zonular fibers; ciliary muscles

102
Q

Ciliary muscle is _____ muscle and is controlled almost entirely by _____

A

Smooth; parasympathetic nerves

103
Q

When focusing distant objects, tension on the lens is ______. The lens ______ and has (more/less curvature)

A

increased; flattens; less curvature

104
Q

when focusing near objects, tension on the lens is ______. The lens rounds up and curvature (increases/decreases)

A

Released; curvature increases

105
Q

The refractive power of the lens is greatest when:

A

Curvature is the greatest

106
Q

Emmetropia

A

Correct focus

107
Q

Myopia

A

Nearsightedness

108
Q

Hyperopia

A

Farsightedness

109
Q

Myopia:
1) Where do light rays focus?
2) Are far or near objects blurry?
3) How is this corrected?

A

1) in front of the retina
2) far/distant objects are blurry
3) with biconcave lens- cause light rays to diverge so rays are brought to focus on the retina

110
Q

Hyperopia
1) Where do light rays focus?
2) near or far objects are blurry?
3) corrected with what type of lens?

A

1) beyond the retina
2) near objects are blurry
3) biconvex lens-add to the refractive power of the lens

111
Q

What regulates the amount of light entering the eye

A

Pupil

112
Q

Pupil size is controlled by the _____

A

Iris

113
Q

What are the 2 muscles of the iris

A
  • circular muscle layer
  • radial muscle layer
114
Q

What muscle layer of the iris is controlled by parasympathetic neurons of the ANS

A

Circular muscle layer

115
Q

The _____ of the iris constricts the pupil in bright light, termed ____

A

Circular muscle layer; miosis

116
Q

What muscle layer of the iris is controlled by sympathetic neurons of the ANS

A

Radial muscle layer

117
Q

The _____ of the iris dilates the pupil in dim light, termed ____

A

Radial muscle layer; mydriasis

118
Q

The _____ is the neural portion of the eye

A

Retina

119
Q

What are the 5 types of neurons in the retina?

A
  • photoreceptors (rods and cones)
  • bipolar cells
  • ganglion cells
  • horizontal cells
  • amacrine cells
120
Q

What are the 3 distinct layers of the retina and what is present in each layer?

A
  • outer: contains rods and cones
  • middle: contains bipolar, horizontal, and amacrine cells
  • inner: contains ganglion cells
121
Q

Rods are the receptors for _____
Cones are the receptors for _____

A

Night vision; color vision

122
Q

Photoreceptors: Rods and Cones
Outer Segment
1) composed of ______ ______ shaped in either regular stacks of discs (?) or flattened sacs(?)
2) contain the _______ _____ that react to light to initiate receptor potentials

A

1) membranous disks-(rods) and (cones)
2) photosensitive pigment

123
Q

Photoreceptors: Rods and Cones

Inner Segment contains cell nucleus that synthesizes:

A

photosensitive compounds

124
Q

Photoreceptors: Rods and Cones
Synaptic Terminal
region of synaptic contact with _____ or ______ cells

A

bipolar or horizontal cells

125
Q

Each photosensitive compound is a compound molecule that contains:

A
  • light absorbing retinal
  • opsin protein
126
Q

What are the 2 configurations retinal exists in?

A

In the dark; 11-cis retinal
In the light; 11-trans retinal

127
Q

What determines which wavelengths of light are optimally absorbed by the photoreceptor

A

The type of opsin present

128
Q

______ is needed for the synthesis of retinal

A

Vitamin A (deficiency leads to visual abnormalities)

129
Q

Rods contain a single photopigment called:

A

Rhodopsin

130
Q

How many pigments do cones contain?

A

3 (blue, green, red)

131
Q

Cones differ in the _____ they contain

A

Types of photopigments (opsins)

132
Q

1) Each opsin type has a sensitivity to light of ______ wavelengths
2) referred to as what color cones?
3) what are the wavelengths of the cones, respectively?

A
  1. different
  2. blue, green, red cones
  3. short, medium, long
133
Q

Color vision is:

A

Trichromatic

134
Q

What is color sensation determined by?

A

The relative AP frequencies generated from each of the 3 colored cones (red, green, and blue)

135
Q

Any spectral color can be produced by:

A

Mixing various proportions of these colors

blue, green, red

136
Q

The photosensitive pigment of rods is

A

Rhodopsin

137
Q

1) Rhodopsin is coupled with a G protein called ______
2) when the G protein is stimulated, what subunits dissociate?
3) G-alpha activates ______, which catalyzes cyclic GMP degradation

A
  1. transducin
  2. alpha, beta, gamma
  3. phosphodiesterase adenylyl cyclase
138
Q

1) light stimulation of _____ in the rods leads to a structural change in ____ _____ and a conformational change in ______
2) activation of the Gs-protein ______, in turn activates phosphodiesterase (PDE)
3) PDE hydrolyzes _____, reducing its concentration and leading to the closure of ______ _____ ____ channels in the membrane
4) produces a _______ receptor potential

A

1) rhodopsin, 11-retinal (cis-to trans-); opsin
2) transducin
3) cGMP, cGMP-gated Na+ channels
4) hyperpolarizing

139
Q

What channels are present in the outer segment membrane of both rod and cone photoreceptors?

A

Cyclic GMP-gated ion channels

140
Q

What is responsible for the light induced changes in electrical activity of photoreceptors?

A

Cyclic GMP gated ion channels

141
Q

1) leads to a _____ in cGMP levels
2) closing of the ____ permeable channels
3) photoreceptor produces a _____ receptor potential

A
  1. decrease
  2. Na+
  3. hyperpolarizing
142
Q

In the Dark
1) cGMP levels are _____
2) cGMP binds to and opens _____ permeable channels
3) ____ enter
4) _______ receptor potential is generated in photoreceptor cells

A

1) high
2) Na+
3) Na+ (or other cations)
4) depolarization

143
Q

Explain the steps of response of photoreceptor to light

A

1) light is absorbed by photopigment
2) Retinal and Opsin dissociate
3) Transducin is activated
4) Phosphodiesterase is activated
5) cGMP levels in cytosol decrease
6) Na+ channels close
7) With less sodium entering the cell, the cell hyperpolarizes
8) Ca2+ channels close
9) Transmitter release is decreased
10) Graded potential in bipolar cell gets smaller

144
Q

Explain the steps of the state of photoreceptor in the dark

A

1) cGMP levels are high
2) sodium channels are open
3) Sodium enters the cell, causing a depolarization that spreads from the outer segment to the terminal
4) Ca2+ open in response to depolarization
5) Calcium enters the cell, triggering exocytosis of transmitter
6) Transmitter causes graded potentials in bipolar cell

145
Q

Vision
1) _____ ______ formed by the axons of ganglion cells of the retina
2) CN ____ exits each eye and combines in front of the brainstem to form the _____ ______

A

1) Optic Nerve (CN II)
2) CN II, optic chiasm

146
Q

What does light from the left visual field strike?

A

the nasal retina of the left eye and the temporal retina of the right eye

147
Q

The ganglion axons from the left eye retina _____ to the right brain at the optic chiasm while ganglion axons from the right eye retina stay on?

A

decussate; ganglion axons from the right eye stay on the same side

148
Q

2 _____ ____ emerge from the optic chiasma to the associated lateral geniculate nucleus (LGN) of the ______

A

Optic tracts; thalamus

149
Q

Where does the neural pathway terminate

A

Primary visual cortex

150
Q

Anatomic Distribution of Rods and Cones
___ density throughout the retina, with a sharp peak in the ______

A

Low; fovea

151
Q

Fovea

A

Small depression within the retina where visual acuity is the greatest

152
Q

Anatomic Distribution of Rods and Cones
Rods
_____ density throughout the retina but absent in the _____
____ _____ is the region on the retina where the optic nerve leaves the eye. There are no photoreceptors in this area so does not respond to light, forming a ______

A

High; fovea; optic disk; blind spot

153
Q

Visual acuity

A
  • Degree to which details of objects are perceived
  • defined as the shortest distance by which 2 lines can be separated and still be perceived as 2 lines
154
Q

Visual acuity is often determined by using _____ viewed from a distance of 20 ft

A

Snellen Letter Charts

155
Q

What is a disease in which there is gradual deterioration of visual acuity

A

Age-related macular degeneration

156
Q

What causes color blindness genetically

A

Inherited abnormality
inherited as recessive and X-linked
8% males, 0.4% females

157
Q

What is the most common color blindess

A

Red/green color blindness

158
Q

Transient blue-green color weakness occurs as a side effect in individuals taking ___

A

Viagra for the treatment of ED because the drugs inhibit retinal phosphodiesterase

159
Q

What charts are used to test for color blindess

A

Isihara Charts

DEN 7101S Human Structure and Function II (21 decks)

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