Chapter 15 Special Senses Flashcards
1
Q
what is the bony socket the eye is found within
A
orbit
2
Q
what are the three “tunics” of the eye?
A
fibrous tunic - sclera + cornea
vascular tunic - choroid +iris + ciliary body
nervous tunic - retina
3
Q
what is the sclera made of?
A
thick collagen
4
Q
what is the cornea made of?
A
thin collagen
5
Q
where does refraction first take place?
A
within the cornea
6
Q
axons of cells from the retina form what?
A
optic nerve
7
Q
is the retina single or multi layered?
A
multilayered
8
Q
what is the anterior cavity made up of?
A
anterior and posterior chamber
aqueous humor
9
Q
what does the anterior chamber of the eye consist of?
A
between cornea and iris
10
Q
what does the posterior chamber of the eye consist of?
A
between iris and lens
11
Q
what is the posterior cavity made of?
A
aka vitreous chamber
made up of vitreous humor
12
Q
how is aqueous humor made and reabsorbed?
A
produced by ciliary body
reabsorbed through sclera venous sinus (aka: canal of Schlem)
13
Q
what is the cause of glaucoma?
A
result of build up of aqueous humor which causes pressure build up within the eye which damages retina and optic nerve over time
14
Q
what is the function of the iris?
A
smooth muscle that controls the amount of light that enters
15
Q
what is the name of the muscle within the iris responsible for dilation?
A
radial muscle (sympathetic input)
16
Q
what is the name of the muscle within the iris responsible for constriction?
A
circular muscle (parasympathetic)
17
Q
what is the cranial nerve responsible for autonomic reflexes of the iris?
A
Oculomotor nerve III
18
Q
which structure is responsible for the SECOND refractive surface?
A
lens
19
Q
what are five features of the lens?
A
transparent elastic capsule biconvex avascular suspensory ligaments
20
Q
what are the two functions of the ciliary body?
A
focus the lens
produce aqueous humor
21
Q
how does the ciliary body and suspensory ligaments work the lens so that you can see a far distant object?
A
ciliary muscle relaxed
suspensory ligaments tight
lens elongated
22
Q
how does the ciliary body and suspensory ligaments work the lens so that you can see a close-up object?
A
ciliary muscle contracts
suspensory ligaments loosen
lens thickens
THIS IS WHY STUDYING TIRES MY EYES
23
Q
what does accommodation of the eye mean?
A
the process of changing the shape of the lens in order to focus vision
24
Q
define emmetropia
A
normal vision
rays focus on retina perfectly
25
define myopia, the cause, and what is needed to correct it?
nearsightedness
rays focus in front of retina
due to long eyeball or thick lens
concave lens can correct
26
define hyperopia, the cause, and what is needed to correct it?
farsightedness
rays focus behind the retina
due to short eyeball or thin lens
convex lens can correct
27
define astigmatism, the cause, and what is needed to correct it?
rays do not focus
light bends in irregular pattern
due to cornea or lens being irregular in shape
uneven lens can correct
28
what special type of cells can be found only in special senses like within retina?
bipolar cells
29
what are the two layers of the retina?
pigmented epithelium
| neural retina
30
what is the retina composed of?
receptor cells
several kinds of neurons
axons leading to optic nerve
31
what kind of vision do "rods" allow for?
colorless vision in dim light
| only gives general outlines of images
32
what kind of vision do "cones" allow for?
colorful vision in bright light
| allow for sharp visual acuity
33
what is a cataract and what causes them?
clouding of the LENS
sometimes congenital, mostly result in age-related hardening and thickening of lens; diabetes; heavy smoking; exposure to heavy sunlight; steroid use
34
what is pupillary constriction?
constricts pupils in order to prevent most divergent light rays from entering the eye
these divergent light rays would not focus properly and cause blurred vision
35
what is convergence of the eye?
medial rotation of the eye
| closer an object is, the more need for eyes to be focused medially
36
rods or cones, which is more photosensitive?
rods (dark vision)
37
what is the reason rods create blurry images instead of clear ones?
rods participate in converging pathways
| 100 rods can feed into each ganglion cell, causing summated, collective information being gathered
38
how do the cones differ from rods that make it so it perceives sharp images?
each cone are directly connected to an individual bipolar cell
Hundreds of rods are connected to an individual bipolar cell
39
what is the point of the eye where cones are concentrated at and no rods are present?
fovea centralis within the macula lutea
40
how do our eyes interpret color?
light is absorbed into molecule retinal and combines with proteins called opsins
depending on the type of opsin retinal is bound to determines the different wavelengths of color spectrum
the cones in our eyes are best suited to pick up certain wavelengths which allows us to perceive red, green, blue colors
41
what is phototransduction?
process of translating light energy to a electrical signal for the brain to be able to process
42
describe in simple terms the path that light travels to the optic nerve
light hits back of eye onto retina
photoreceptors (rods and cones)
which pick up light and creates AP
Then the bipolar cell transfers this electrical signal to the ganglionic cell
the ganglionic cell's axons make up the optic nerve
43
what is the protein that have to do with rods?
rhodospin
44
what is the protein that have to do with cones?
photospin/ iodospin
45
what is rhodopsin made up of when there is no light?
11-cis-retinal and opsin
46
what happens to rhodospin when light hits it? Why is this important?
breaks down into all-trans-retinal and opsin
| the changing of the shape helps with transduction of light waves
47
what are the three colors that cones are specialized for?
red, green, and blue
48
what is the point of the eye that is our blind spot?
optic disk
49
describe the full length of our visual pathway that leads to brain, starting with photoreceptors and ending with what cortex of what lobe in our brain (9 total structures)
```
photoreceptors
bipolar cells
ganglionic cells
optic nerve
optic chiasma
optic tracts
thalamus
optic radiations
visual cortex in occipital lobe
```
50
when does light adaptation occur
when we move from darkness into bright light
51
how do our eyes allow for light adaptation?
transducin migrates to center of vision in order to shut off rhodopsin from producing signals (within rods)
52
what does dark adaptation mean?
when we go from a well-lit area to dark
53
how do our eyes allow for dark adaptation?
transducin returns to outer segment of eye which allows for rhodospin to "turn back on"
54
how long does it take for light vs dark adaptation to occur?
light: 5-10 minutes
dark: 20-30 minutes or several hours
55
what portion of the brain is responsible for the reflex centers for the muscles of our eyes?
superior colliculi
56
depth perception is dependent on____
the convergence of both eyes
57
what are the small muscles that protect the ear drum from loud noises? how do they help?
tensor tympani and stapedius
| contract to limit ossicles' vibration and minimize damage to hearing receptors
58
what bone does the bony labyrinth rest within?
temporal bone
59
what are the layers within the bony labyrinth?
```
endolymph (fluid filled innermost)
membranous labyrinth (tissue incasing endolymph fluid)
perilymph (fluid filled)
bony labyrinth (outermost)
```
60
what is the purpose of the fluid within the cochlea?
allow us to hear
61
what is the purpose of fluid within semicircular canals?
allows for balance
62
what is the purpose of eustachian tube?
allow to pressure to escape or enter into ear
63
what the the three auditory ossicles?
malleus, incus and stapes
64
within the vestibule are two structures called the saccule and utricle, which of each are responsible for cochlea or semicircular canals?
saccule houses equilibrium receptors of the cochlea
utricle houses equilibrium receptors of the semicircular canals
65
describe the three layers of the cochlea, what is found within each?
```
scala vestibuli (upper most chamber) contain perilymph
scala media (center) contains organ of corti and endolymph
scala tympani (lower most chamber)
```
66
low and high frequencies are encoded at which regions of the cochlea?
high frequencies at base
| low frequencies at apex
67
what is the membrane and cell structures that are heavily responsible for the interpretation of sound?
basilar membrane and hair cells
68
the fibers within the basilar membrane near the base of the cochlea are ____
short and stiff which help with high frequency sounds
69
the fibers within the basilar membrane at the apex of the cochlea are_____
long and floppy which help with lower frequency sounds
70
what membrane rests on top of the hair cells? what is the purpose?
tectorial membrane
| allow for opening and closing of channels on outer hair cells to depolarize and hyperpolarize the cell
71
briefly describe the auditory pathways to the brain
```
hair cells
vestibulocochlear nerve VIII
inferior colliculus within midbrain
thalamus
auditory cortex within the temporal lobe
```
72
what is the difference between inner and outer hair cells
inner: responsible for the perception of sound, gathers information to cranial nerve
outer: responsible for producing AP to basilar membrane in order to vibrate
73
how do we perceive pitch?
when a sound is composed of tones of many frequencies, it activates several cochlear hair cells thus produced multiple tones
74
how do we perceive loudness?
produced by large sound waves creating large movements in basilar membrane which create more frequent action potentials which we can perceive to be loud sounds
75
how do our ears localize sound?
relative intensity and relative timing of sound waves reaching the two ears
76
what is a macula and where are they locted?
sensory receptor organs
| located within each saccule and utricle
77
what are the structures found within macula?
hair cells
otolith membrane (jelly like)
otoliths (ear stones/crystals)
78
what is the structure within the utricle and saccule that helps the semicircular canals function
crista ampullaris
79
macula primary help with with movements?
respond to horizontal and vertical movements
80
crista ampullaris primary helps with what in regards to movement?
changes in velocity of rotational movements
81
what are 4 causes of hearing loss
sensory presbycusis: listening to loud music can atrophy receptor cells
neural presbycusis: loss of neurons in the auditory pathways
metabolic presbycusis: rare; caused by lack of nutrients
mechanical presbycusis: stiffening of ossicles or hair cells due to old age
82
what is conductive hearing loss related to, what can help this?
impacted earwax
tumors
infections
hearing aid can aid this
83
what is sensorineural hearing loss? what can help?
issue with cochlea and auditory nerve
| cochlear implant can possibly aid this
84
where are the crista ampullaris located?
amullae of semicircular canals
85
what primarily effects macula vs cristae?
macula: gravity
| cupula of cristae: inertia
86
what is the cranial pathway for equilibrium?
maculae/ampulae
vestibular branch of vestibulocochlear VIII
thalamus
vestibular cortex within parietal lobes
87
what is another term for taste?
gustation
88
what is the sensitive portion of the taste receptor cell?
gustatory hair containing chemoreceptors
89
what is the difference between taste and sight in terms of sensory cells?
taste receptors are modified epithelial cells instead of bipolar neurons
90
what is the job of the supporting cells?
help reestablish damaged taste cells
91
what are the features within a taste bud?
taste cell
supporting cells
taste pore
92
what is the gustatory pathway to the brain?
Facial nerve VII, glossopharyngeal nerve IX, Vagus nerve X
medulla oblongata
thalamus
gustatory cortex within insula
93
what are the five primary sensations that chemoreceptors within tongue are stimulated by? what are their corresponding associated tastant?
```
sweet - sugars/carbs
sour - acid (low pH)
salty - salt
bitter - alkaloids (high pH/hydrogen)
umami/savory - amino acids
```
94
define ageusia
complete loss of taste
95
hypogeusia
reduced sense of taste
96
dysgeusia
distortion of sense of taste
97
parageusia
persistent abnormal taste
98
hypergeusia
abnormally heightened sense of taste
99
at what age do taste receptors begin to fade? what is the reason?
50 years old
| loss of tongue papillae and decrease in saliva production
100
what does sequential stimulation refer to?
eat more slowly...enjoy it more
101
what other factors is smell associated with?
memories and emotions
| taste
102
what kind of receptors does smell have
chemoreceptors
103
how is the sense of sight and smell similar in terms of the cells they both share?
bipolar cells in superior most portion of nasal cavity
104
axons of the bipolar cells of smell extend through where and synapse where?
extend through cribiform plate to form Olfactory Nerve I
| synapse in olfactory bulbs
105
what stimulates olfactory chemoreceptors and what is the process of turning that into a electrical impulse?
odorants stimulate odorant receptor protein
| odorant receptors begin chain of events that depolarize neuron
106
what does olfactory code refer to?
odor that is coded for by a particular set of receptors
| complex smells have multiple odorants that contribute to smell
107
describe the olfactory pathways to the brain
```
receptors cells
olfactory bulb
olfactory nerve
olfactory cortex: lateral area (temporal)
medial area (frontal)
intermediate area (frontal)
```
108
what is the reason for needing to transmit to the latera, medial, and intermediate area of the olfactory pathways
lateral: temporal conscious awareness of smell
medial: frontal connection to limbic system
intermediate: frontal feeds back to inhibit olfactory bulbs
109
what are damaged cells replaced by within the olfactory division
basal cells
110
what is one sense that does not pass through talamus?
olfactory sense (smell)
