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HLSC 126 - Human Physiology I > Chapter 5A - Senses > Flashcards

Chapter 5A - Senses Flashcards

1
Q

Posterior Cavity

A

-separated from anterior cavity by the lens
-between lens and retina
-contains vitreous humor

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2
Q

Anterior Cavity

A

-separated from posterior cavity by the lens
-between cornea and lens
-contains aqueous humor

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3
Q

Lens

A

-bends light to focus it on the retina
-separates anterior and posterior cavities

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4
Q

Vitreous Humor

A

-gel-like
-not drained out
-helps maintain the shape of the eyeball

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5
Q

Aqueous Humor

A

-nutrient rich (provides cornea and lens)
-drained and made fresh
-produced at 5mL/day
-watery, plasma-like fluid

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6
Q

Why don’t the cornea and lens have blood vessels?

A

It would impede with the passage of light

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7
Q

What structure drains aqueous humor?

A

Canal of Schlemm

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8
Q

Cornea

A

-transparent lens
-nutrient fed by aqueous humor
-outer layer where light passes into eye

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9
Q

Sclera

A

-tough outer layer of connective tissue
-white part of the eye

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10
Q

Choroid

A

-layer underneath sclera that has blood vessels which nourish retina
-black pigmented layer

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11
Q

Ciliary Body

A

-formed from choroid layer
-contains ciliary muscle that changes shape of the lens
-contains suspensory ligaments and zonules
-also houses capillary network responsible for aqueous humor

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12
Q

Iris

A

-formed from choroid layer
-pigmented layer of smooth muscle
-complicated color formation that is more complex than DNA
-mulit-unit

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13
Q

Pupil

A

-size adjusted by iris muscles to control amount of light that enters the eye
-contains 2 sets of smooth muscle networks

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14
Q

Circular Muscle Network (Pupil)

A

-muscle fibres run in a ring like fashion
-makes the pupil smaller when they contract in response to bright light
-innervated by parasympathetic nerve endings

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15
Q

Radial Muscle Netwrok (Pupil)

A

-muscle fibres project outward from pupillary margin
-increases size of pupil in response to dim light
-innervated by sympathetic nerve endings

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16
Q

Conjective

A

-outermost membrane
-easily infected

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17
Q

Retina

A

-innermost layer under the choroid
-outer layer and inner nervous tissue layer
-contains photoreceptor: rods and cones

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18
Q

Why are choroid and retina highly pigmented?

A

To prevent reflection or scattering of light in the eye

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19
Q

Optic Disk

A

-blind spot (no rods or cones)
-entry/exit point of nerves and blood vessels

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20
Q

Optic Nerve

A

-CN II
-sends signals to central nervous system

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21
Q

Fovea Centralis

A

-region of the sharpest vision
-only cones are found here

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22
Q

Macula Lutea

A

-center of the visual field
-immediately surrounds fovea
-high acuity

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23
Q

CN I

A

?

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24
Q

CN II

A

optic nerve

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25
Q

CN III

A

oculomotor nerve

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26
Q

CN IV

A

trochlear

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27
Q

CN V

A

trigeminal

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28
Q

CN VI

A

abducens

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29
Q

CN VII

A

facial

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30
Q

CN VIII

A

ear

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31
Q

Formation and Drainage of Aqueous Humor

A

-formed by: capillary network in ciliary body
-drains into: canal of Schlemm and eventually enters the blood

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32
Q

Accomodation

A

-change in strength and shape of the lens
-accomplished by ciliary muscles and suspensory ligaments
-goal=perfect vision by focusing light on the retina

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33
Q

Far Vision

A

-ciliary muscle is relaxed
-lens is flat
-taut suspensory ligaments
-sympathetic stimulation

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34
Q

Near Vision

A

-ciliary muscle contracts
-lens is rounded
-slackened suspensory ligaments
-parasympathetic stimulation

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35
Q

Which branch of the nervous system controls the ciliary muscle?

A

autonomic nervous system (ANS)

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36
Q

Glaucoma

A

-drainage of aqueous humor is blocked
-pressure build-up of fluid
-if not treated: degenerates optic nerve (blindness)
-treated with: medication or surgery

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37
Q

Macular Degeneration

A

-“donut vision”
-main concern for blindness in the Western hemisphere
-irreversible
-loss of photo receptors in the macula
-lose middle of visual field and are only left with less distinct peripheral vision
-results from age

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38
Q

Emmetropia

A

-flattening and rounding of the lens to give perfect vision
-normal eye

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39
Q

Hyperopia

A

-farsightedness
-focal point falls behind the retina
-corrected with convex lens

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40
Q

Myopia

A

-nearsightedness
-focal point falls in front of the retina
-corrected with concave lens

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41
Q

Presbyopia

A

-age related reduction in accommodative ability
-usually occurs middle age (45-55)
-use of reading glasses required

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42
Q

Photoreceptors

A

-The retina which contains the receptors is an extension of the CNS
-rods and cones transform light energy into electrical signals which are sent to the CNS
-retina contains 3 layers of excitable cells

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43
Q

Outermost Retinal Layer

A

-closest to the choroid
-contains rods and cones whose light-sensitive ends face the choroid (away from incoming light)

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44
Q

Middle Retinal Layer

A

-bipolar cells

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45
Q

Inner Retinal Layer

A

-ganglion cells
-axons join to form the optic nerve

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46
Q

Rods

A

-more numerous than cones
-used in night vision
-shades of grey vision
-low acuity
-high sensitivity
-more convergence in retinal pathways
-more numerous in peripheral region

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47
Q

Cones

A

-less numerous
-used in day vision
-colour vision
-high acuity
-less sensitivity
-little convergence in retinal pathways
-concentrated in fovea and macula

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48
Q

Night Blindness

A

-vitamin A deficiency
-a rod issue
-unable to see well at night or in poor light
-reversible

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49
Q

Color Blindness

A

-inherited
-cone issue
-more prominent in males than females

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50
Q

How many parts make up a photo receptor?

A

Three

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51
Q

Outer Segment

A

-discs
-detect light stimulus
-holds pigment

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52
Q

Inner Segment

A

-contains metabolic machinery of the cell

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53
Q

Synaptic Terminal

A

-transmits signal generated in photoreceptor upon light stimulation to next cells in visual pathways

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54
Q

Photopigments

A

undergo chemical alterations when activated by light

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55
Q

Opsin

A

-protein
-integral part of the disc membrane

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56
Q

Retinal (aka retinene)

A

-vitamin A derivative
-light absorbing part of the photopigment

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57
Q

Rhodopsin

A

-activated in light
-rod photopigment
-absorbs all visible wavelengths
-shades of grey promote different intensities

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58
Q

3 Types of Cones

A

-red, green, and blue
-respond selectively to various wavelengths of light

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59
Q

Phototransduction

A

-process of converting light stimuli into electrical signals
-usually receptors depolarize on stimulation: however, photoreceptors hyperpolarize on light absorption

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60
Q

Sensitivity

A

varies through light and dark adaptation

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61
Q

Dark Adaptation

A

-gradually distinguish objects as you enter dark area
-due to the regeneration of rod photopigments that were previously broken down from light exposure

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62
Q

Light Adaptation

A

-gradually distinguish objects as you enter an area with more light
-due to rapid breakdown of cone photopigments

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63
Q

Photoreceptors in the Dark

A

-retinol is inactive
-chemically gated channels respond to 2nd messenger cGMP which keeps Na+ channels open
-cGMP is in high concentration
-Na+ channels are open in the absence of stimulation (light)
-cell becomes depolarized
-passive spread of depolarization from outer segment to synapse keeps Ca2+ channels open
-Ca2+ triggers release of inhibitory neurotransmitter

64
Q

Photoreceptors in Light

A

-concentration of cGMP is decreased
-photopigment activated, which activated transducin (G-protein), which activates phosphodiesterase enzyme
-the enzyme degrades cGMP, thus decreasing its concentration
-Na+ channels close, causing hyperpolarization
-spreads from the outer segment to synapse
-Ca2+ channels close, and NT release from the synapse is reduced

65
Q

What inhibits photoreceptors?

A

-light (their stimulus), which causes them to hyperpolarize
-this process is the reverse of normal: inhibition by adequate stimulus
-brighter the light, the greater the hyperpolarizing response and the greater the reduction of inhibitory NT release

66
Q

What excites photoreceptors?

A

-darkness, which causes them to depolarize
-“excited in the absence of stimulation”

67
Q

Retinal Processing of Light Input

A

-photoreceptors synapse with bipolar cells (graded potential)
-bipolar cells terminate of the ganglion cells (action potential)
-ganglion cell axons form the optic nerve
-optic chiasm
-optic tract
-thalamus (lateral geniculate)
-optic radiation
-occipital lobe
=IMAGE!

68
Q

Inhibitory Action on Bipolar Cells

A

-the reduction inhibitory NTs release decreases inhibitory action on bipolar cells
-and removal has the same effect as direct excitation

69
Q

Visual Field

A

what can be seen without moving the head

70
Q

Upside Down Image

A

-the image detected on the retina at the onset of visual processing is upside down and backwards because of the bending of the rays at the lens
-brain must correct the orientation of the image

71
Q

On-center Ganglion Cell (donut hole)

A

increases the rate of firing when light is most intense at the center of its receptive field

72
Q

Off-center Ganglion Cell (donut)

A

increases the rate of firing when the periphery of the field is most intensely illuminated

73
Q

Optic Chiasm

A

-met by optic nerves
-underneath hypothalamus

74
Q

Optic Tracts

A

-reorganized fibers that cross in the chiasm
-each tract carries info from the lateral half of one retina and the medial half of another

75
Q

Hearing

A

neural perception of sound energy

76
Q

External Ear

A

-pinna, ear canal, tympanic membrane
-transmits sound waves to inner ear
-amplifies sound energy

77
Q

Pinna

A

outer piece of cartilage that is used to colect sound waves

78
Q

Ear Canal

A

-most prone to infection
-contains hairs and glands that produce earwax
-prevent airborne particles from interfering with hearing

79
Q

Tympanic Membrane (aka ear drum)

A

-vibrates when struck by waves
-resting air pressure on both sides must be equal

80
Q

Middle Ear

A

-contains ossicles and eustachian tube
-transmits sound waves to inner ear
-amplifies sound energy

81
Q

Ossicles

A

-malleus, incus, stapes
transmits movement from tympanic membrane to oval window

82
Q

Eustachian Tube

A

-connects middle ear to pharynx (back of the throat)
-regulates pressure in the ear (ie. yawning, chewing)

83
Q

Otitis Media

A

-infection of the middle ear
-redness and swelling interfere with sound conduction
-treated with antibiotics

84
Q

Oval Window

A

-the entrance to the cochlea
-seals scala vestibuli from middle ear

85
Q

Inner Ear

A

-houses cochlea and vestibular apparatus

86
Q

Cochlea

A

-contains receptors for conversion of sound waves into nerve impulses which make hearing possible
-fluid filled portion used in hearing
-divided into 3 fluid filled compartments

87
Q

Vestibular Apparatus

A

-necessary for sense of equilibrium
-balance

88
Q

Round Window

A

-membrane covered opening
-seals the scala tympani from the middle ear

89
Q

Cochlear Duct (scala media)

A

-the middle compartment
-houses endolymph (ICF)

90
Q

Vestibular Duct (scala vestibuli)

A

-upper compartment

91
Q

Tympanic Duct (scala tympani)

A

-lower compartment

92
Q

Perilymph

A

-housed in the vestibular and tympanic ducts
-ECF

93
Q

Helicotremma

A

-tip of the cochlear duct where the two outer regions meet

94
Q

Tectorial (vestibular) Membrane

A

-forms the ceiling of the cochlear duct and separates it from scala vestibuli

95
Q

Basilar Membrane

A

-forms the floor of the cochlear duct and separates it from scala tympani
-holds the Organ of Corti

96
Q

Organ of Corti

A

-the sense organ for hearing
-hair cells transduce sound waves
-hair cells arranged in 4 parallel rows: 1 row of inner hair cells and 3 rows of outer hair cells

97
Q

Stereocilia

A

-protrude from the surface of each hair cell
-actin-stiffened microvilli
-contact the tectorial membrane

98
Q

Role of Hair Cells

A

-generate neural signals when their surface hairs are mechanically deformed by fluid movements in the inner ear

99
Q

Kinocilium

A

tallest hair cells
-bending stereocilia towards kinocilium = DEPOLARIZATION
-kinocilium towards stereocilia = REPOLARIZATION

100
Q

Step 1

A

tympanic membrane vibrates when struck by sound waves

101
Q

Step 2

A

middle ear transfers vibrations through ossicles to the oval window

102
Q

Step 3

A

waves in cochlear fluid set the basilar membrane in motion

103
Q

Step 4

A

receptive hair cells are bent as basilar membrane is deflected up and down

104
Q

Step 5

A

mechanical deformation of hair cells is transduced into neural signals that are transmitted to the auditory cortex in the temporal lobe of the brain for sound perception

105
Q

Frequency

A

-measure in Hertz
-1000 to 3000Hz

106
Q

Amplitude

A

-measured in Decibels
-60dB
-rock concert is about 120dB

107
Q

Conductive Hearing Loss

A

-sound waves are not adequately conducted to set the fluid in motion
-could be from: blockage, earwax, infection, ear drum damage
-reversible

108
Q

Central Hearing Loss

A

-neural pathways are damaged
-functioning of auditory cortex is impaired
-could result from a stroke

109
Q

Sensorineural Hearing Loss

A

-sound waves transmitted but not not translated into neural signals
-defect can lie in: organ of corti, auditory nerve, ascending auditory pathway, or the auditory cortex
-best fixed with cochlear implant
-not reversible

110
Q

Vestibular Apparatus…

A

-Provides essential info for the sense of equilibrium
-head and eye coordinated movement
-posture
-balance

111
Q

Similarities of Vestibular Apparatus with Cochlea and organ of Corti

A

-cochlea: VA contains endolymph and are surrounded with perilymph
-Corti: hair cells that respond to mechanical deformation

112
Q

Differences between VA and auditory system

A

-VA info doesn’t usually reach conscious awareness

113
Q

Semicircular Canals

A

-detect rotational acceleration or deceleration in any direction
-houses ICF
-3 canal divisions
-CN VIII

114
Q

Superior Canal

A

head nodding “YES”

115
Q

Horizontal Canal

A

head shaking “NO”

116
Q

Posterior Canal

A

L and R head tilt

117
Q

Ampulla

A

-swelling at the base of each canal
-receptive hair cells sit on top of a ridge here
-fluid filled, moves when head does

118
Q

Capula

A

-gelatinous layer where the hairs are embedded
-protrude into the endolymph within the ampulla
-sways in direction of fluid movement like sea weed

119
Q

Vestibulocochlear Nerve CN VIII

A

-vestibular nerve and auditory nerve unite

120
Q

Action Potentials in VA

A

-depolarization increases the release of NT from the hair cell, decreasing the frequency of action potentials in afferent fibers

121
Q

When do semicircular canals not respond?

A

-when head is motionless
-when head is moving in a circle at a constant speed

122
Q

Otolith Organs

A

-provide info about the position of the head relative to gravity
-detect changes in the rate of linear motion
-houses saccule and utricle in a bony chamber between canals and cochlea

123
Q

Saccule

A

-vertical movement
-ie. trampoline, elevator

124
Q

Utricle

A

-horizontal movement

125
Q

Otolith Crystals

A

-calcium carbonate + protein
-suspending in the gelatinous layer

126
Q

Meniere’s Disease

A

-fluid imbalances in the inner ear that lead to dizziness and nausea
-both vestibular and auditory symptoms occur
-vertigo
-tinnitus

127
Q

Inner Hair Cells

A

-transform the mechanical forces of sound (cochlear fluid vibration) into electrical impulses (action potentials)

128
Q

Outer Hair Cells

A

-enhance the response/sensitivity of the inner hair cells
-electromotility: change length in response to changes in membrane potential
-hair cells shorten on depolarization and lengthen on hyperpolarization

129
Q

Auditory Action Potentials

A

-depolarization of hair cells (basilar memb. is deflected upward) increases rate of NT release which increases rate of firing in afferent fibres
-firing rate decreases as less NTs are released when hyperpolarized upon displacement in the opposite direction

130
Q

How do hair cells form action potentials?

A

-shifting mechanical deformation opens and closes receptor cell channels, bringing about graded potentials that lead to action potentials which are propogated to the brain

131
Q

Taste (aka gustation)

A

-chemoreceptors are housed in taste buds in mouth and throat
-taste receptors have a 10 day lifespan

132
Q

Taste Pore

A

-opening where fluids come into contact with the surface of receptor cells

133
Q

Taste Receptor Cells

A

-modified epithelial cells with surface folds (microvilli)
-plasma membrane of microvilli contain receptor sites that selectively bind with chemical molecules

134
Q

Tastant

A

-taste-provoking chemical
-binds too receptor cell and depolarizes the cell

135
Q

Cortical Gustatory Area

A

-region in the parietal lobe adjacent to the tongue area of the somatosensory cortex
-gustatory pathways are uncrossed

136
Q

Salty

A

-stimulated by chemical salts
-NaCl

137
Q

Sour

A

-acids which contain a free hydrogen ion, H+, that blocks K+ channels
-citrus fruits

138
Q

Sweet

A

-evoked by particular configuration of glucose
-binding of glucose with receptor activated cGMP (G-protein), the second messenger pathways blocks K+ channels

139
Q

Bitter

A

-chemically diverse group of tastants
-ie. alkaloids, toxic plant derivatives, poisonous substances
-G-protein, Gustducin, sets off 2nd messenger pathway

140
Q

Umami

A

-meaty/savoury
-triggered by amino acids, esp. glutamate (MSG)
-gluatmate binds to a G-protein coupled receptor to start a 2nd messenger pathway

141
Q

Cranial Nerves of Taste

A

??

142
Q

Olfactory Receptor Cells

A

-renewable afferent neurons
-receptor portion lie in olfactory mucosa
-axons form olfactory nerve

143
Q

Olfactory Mucosa

A

-3cm^2 path of mucosa in the ceiling of the nasal cavity
-contains the 3 cell types

144
Q

Supporting Cells

A

secrete mucus which coats nasal passages

145
Q

Basal Cells

A

precursors for new olfactory receptor cells which get replaced every 2 months

146
Q

How many different types of olfactory receptors exist?

A

1000

147
Q

Odorants

A

-molecules that can be smelled
-receptor sites on cilia

148
Q

Olfaction

A

-binding to receptor cell activates G-protein, triggering cAMP 2nd messenger system to open Na+ channels
-action potential triggered in afferent fibre

149
Q

Frequency of APs

A

depends on concentration of stimulating chemical molecules

150
Q

Olfactory Bulbs

A

-where afferent fibres synapse
-contains several layers of cells (functionally similar to retinal layers)

151
Q

Glomeruli

A

-small ball-like neural junctions that line the olfactory bulbs
-synapse with mitral cells
-“smell files”: forst relay/sorting station for processing olfaction

152
Q

Mitral Cells

A

-where olfactory receptors terminate in the glomeruli
-refine smell signals and relay them to the brain (2 possible routes)

153
Q

Subcortical Route

A

-goes to limbic system: primary olfactory cortex in lower medial sides of temporal lobes
-hypothalamic involvement: coordination between smell and behavioural reaction

154
Q

Cortical Route

A

-from thalamus to cortex
-important for perception and fine discrimination of smell

155
Q

Adaptability

A

-sensitivity of an odour diminishes after a short period of time
-highly adaptive
-odour-eating enzymes

156
Q

Vomeronasal Organ

A

-detects pheromones
-nonvolatile chemical signals passed subconsciously between individuals
-triggers sociosexual behaviours

HLSC 126 - Human Physiology I (5 decks)

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