Special Senses Flashcards
1
Q
This is the ratio of light in a vacuum to the velocity in that substance.
A
Refractive index
2
Q
What is the velocity of light in a vacuum?
A
300,000 km/sec
3
Q
When light is passing through the various layers of the eye, where would the greatest differences in refractive indices be located?
A
When light is transitioning from the air to the cornea
4
Q
What is a diopter? How are they expressed for convex and concave lenses?
A
- A diopter is 1 meter/focal length
- Diopters are + for convex lenses
- Diopters are - for concave lenses
5
Q
Lens strength can vary from ___ to ___ diopters.
A
20-30 D
6
Q
The ability to increase refractive power increases or decreases with age?
A
Decreases
7
Q
Parasympathetic or Sympathetic excitation increases lens strength?
A
Parasympathetic
8
Q
Parasympathetic excitation causes contraction of the ciliary muscle allowing relaxation of suspensory ligaments attached radially around the lens. This causes the lens to become more convex and thereby increasing refractive power. What is this process called?
A
Accommodation
9
Q
This condition is characterized by the loss of elasticity of the lens with age and the subsequent loss of accommodation.
A
Presbyopia
10
Q
This term is used to describe normal vision in which the ciliary muscle is relaxed in distant vision.
A
Emmetropia
11
Q
This condition is also known as “farsightedness” in which the focal point is behind the retina.
A
Hyperopia
12
Q
This condition is also known as “nearsightedness” in which the focal point is in front of the retina.
A
Myopia
13
Q
What type of lens is used to correct hyperopia? Myopia?
A
Hyperopia: convex lens. Can temporarily be corrected for by contracting the ciliary muscle
Myopia: concave lens
14
Q
This condition is characterized by an irregularly shaped cornea (more common) or lens (less common)?
A
Astigmatism
15
Q
This is commonly used to test the visual acuity of an individual my measuring the ratio of what that person can see compared to an individual with normal vision.
A
Snellen eye chart
16
Q
According to the Snellen eye chart, what is considered normal visual acuity? Less? More?
A
20/20: normal
20/40: less
20/10: more
17
Q
Which area of the eye has the greatest visual acuity?
A
Fovea centralis: composed almost entirely of long slender cones
18
Q
What allows the fovea centralis to have such great acuity?
A
The blood vessels, ganglion cells, inner nuclear and plexiform layers are displaced laterally allowing light to pass relatively unimpeded to receptors
19
Q
What are the three cues of depth perception?
A
- Relative size
- Moving parallax
- Seteropsis: binocular vision
20
Q
The closer the object, the larger it appear. This is describing what cue of depth perception?
A
Relative size (only needs one eye)
21
Q
As the head moves, objects closer move across the visual field at a greater rate. This is describing what cue of depth perception?
A
Moving parallax (only needs one eye)
22
Q
A slight difference in position of the visual image on both retinas, closer objects are more laterally placed. This is describing what cue of depth perception?
A
Stereopsis-binocular vision. Requires both eyes
23
Q
This substance is secreted by the ciliary body. It flows into the anterior chamber of the eye and drains into the Canal of Schlemm (vein).
A
Aqueous humor
24
Q
This condition is characterized by an increase in intraocular pressure leading to the compression of the optic nerve and eventual blindness.
A
Glaucoma
25
This structure is a peripheral extension of the CNS and processes visual signals. It contains photoreceptors, bipolar, ganglion, horizontal, and amacrine cells.
Retina
26
These are the only retinal cells that are capable of generating action potentials.
Ganglion cells
27
What happens to photoreceptors when light strikes them?
- Light breaks down rhodopsin (rods) and cone pigments (cones)
- Rhodopsin decreases leading to a decrease in Na+ conductance
- Photoreceptors hyperpolarize
- Less neurotransmitter (glutamate) is released
28
How does the retina respond to darkness?
- Rods/cones depolarize
- Neurotransmitters increase
- Hyperpolarize "on" bipolar cells and depolarize "off" bipolar cells
29
How does the retina respond to light?
- Rods/cones hyperpolarize
- Neurotransmitters decrease
- Depolarize "on" bipolar cells and hyperpolarize "off" bipolar cells
30
These are non-spiking inhibitory interneurons that make complex synaptic connections with photoreceptors. They are responsible for later inhibition and turned off in the dark due to dopamine released from interplexiform cells.
Horizontal cells
31
These cells connect photoreceptors to either ganglion cells or amacrine cells.
Bipolar cells
32
What are the two types of bipolar cells?
Invaginating: "on"-hyperpolarized by glutamate
| Flat bipolars: "off"-depolarized by glutamate
33
These cells receive input from many rod bipolar cells (convergence) and project to the feet of cone bipolar cells, which connect to ganglion cells.
Amacrine cells
34
These cells can be of the "on" or "off" variety and are the only retinal cells that are capable of generating an action potential.
Ganglion cells
35
What are the three types of ganglion cells?
- X(P) cells
- Y(M) cells
- W cells
36
These ganglion cells receive input from the bipolar cells, have a small receptive field, have a slow conduction velocity, are slow adapting, and have projections to the parvocellular part of the lateral geniculate nucleus of the thalamus.
P(X) ganglion cells (responsible for color vision)
37
These ganglion cells receive input from amacrine cells, have a large receptive field, a fast conduction velocity, are fast adapting, and have projections to the magnocellular part of the lateral geniculate nucleus of the thalamus.
M(Y) ganglion cells (sensitive to movement and brightness)
38
These ganglion cells are the smallest, have the slowest conduction velocity, and have broad receptive fields (rods).
W ganglion cells
39
What is the receptive field size in the fovea?
The ratio can be as low as 1 cone to 1 bipolar cell to 1 ganglion cell
40
What is the receptive field size in the peripheral retina?
Hundreds of rods can supply a single bipolar cell and many bipolar cells connected to one ganglion cell
41
What happens during dark adaptation?
- an increase of retinal sensitivity (10000 fold)
- cones adapt within the first 10 min (100 fold)
- pupil dilation
42
What are the three types of cones?
- Blue sensitive (445 nm)
- Green sensitive (535 nm)
- Red sensitive (570 nm)
43
This is a sex-linked trait carried on the X chromosome. It occurs almost exclusively in males, but transmitted by females.
Color blindness (red-green color blindness is the most common)
44
This condition is characterized by a loss of red cones. Individuals have an overall decrease in the visual spectrum.
Protanope
45
This condition is characterized by a loss of green cones. Individuals have a normal overall visual spectrum.
Deuteranope
46
The loss of blue cones is rare and may be under-represented. What is it referred to as?
Blue-weakness
47
What test is used to find problems distinguishing green, yellow, orange, and red.
Ishihara chart
48
What is the visual pathway?
- Optic nerve to optic chiasm
- Optic chiasm to optic tract
- Optic tract to the lateral geniculate (synapses occur here)
- Lateral geniculate to the primary visual cortex (geniculocalcarine radiation)
49
When a lesion occurs in the optic nerve, what happens to the visual field?
Blindness in one eye
50
When a lesion occurs in the optic chiasm, what happens to the visual field?
Bitemporal hemianopia (loss of peripheral vision/tunnel vision)
51
When a lesion occurs in the optic tract, what happens to the visual field?
Left/right homonymous hemianopia (loss of an entire visual field)
52
What Brodmann area is the primary visual cortex?
Brodmann area 17
53
These cells within the primary visual cortex respond to bars of light/dark above and below layer IV.
Simple cells
54
These cells within the primary visual cortex are motion dependent, but have the same orientation sensitivity as simple cells.
Complex cells
55
These cells within the primary visual cortex are rich in cytochrome oxidaase in the center of each ocular dominance band. It is the starting point of cortical color processing.
Color blobs
56
Visual signals are broken down and sent over parallel pathways. What are these pathways?
Parvo-interblob: high resolution static form of perception (black and white)
Blob: color (V4) and acrhomatopsia
Magno: movement and stereoscopic depth
57
Where does the old visual pathway project? New pathway?
Superior colliculus; cortex
58
What is the old visual pathway associated with?
- Locating objects in the visual field for orientation
- Subconscious
- Blindsight
59
What is the new visual pathway associated with?
Consciously recognizing objects
60
This term is used to describe the ability of individuals who are effectively blind, due to brain damage, to carry out tasks which appear to be impossible unless they can see the objects.
Blindsight
61
This fixation mechanism is controlled by the cortical field bilaterally in the premotor cortex and a person moves their eyes of their own will to fix on an object.
Voluntary fixation mechansim
62
This fixation mechanism is controlled by secondary visual areas in the occipital cortex located in front of the primary visual cortex and works in conjunction with the superior colliculus. An individual will hold their eyes firmly on an object once it has been located
Involuntary fixation mechanism
63
Parasympathetic input plus any cause that would decrease the size of the pupil would result in a decrease in pupillary diameter known as what ?
Miosis
64
Sympathetic input plus any cause that would increase the size of the pupil would result in an increase in pupillary diameter known as what?
Mydriasis
65
This condition is characterized by an interruption of sympathetic nervous supply to an eye. There is a constricted pupil, drooping of the eyelid, and a lack of sweating on the affected side.
Horner's syndrome
66
What extra ocular muscles produce lateral movements?
Medial rectus of one eye and the lateral rectus of the other eye.
67
What extraocular muscles elevate and depress the eye?
Superior and inferior rectus
68
What extraocular muscles lower the eye when it is adducted?
Superior oblique
69
What extraocular muscles elevates the eye when it is adducted?
Inferior oblique
70
What is the innervation of the extraocular eye muscles?
Lateral Rectus: C.N. VI
Superior Oblique: C.N. IV
Superior rectus, inferior rectus, inferior oblique, and medial rectus: C.N. III
71
What does the ossicular system do?
- Reduces the amplitude of a sound by 1/4
| - Increases pressure against the oval window 22x
72
What are the muscles of the ear?
Stapedius and tensor tympani
73
What is the function of the stapedius?
Pulls the stapes outward
74
What is the function of the tensor tympani?
Pulls the malleous inward and tenses the tympanic membrane
75
When contracting alone the stapedius does what to sound? What about the tensor tympani? What happens when both contract?
Diminishes sensitivity; enhances sensitivity; diminishes sensitivity
76
What are the three coiled tubes or chambers of the cochlea?
- Scala vestibuli
- Scala media (cochlear duct)
- Scala tympani
77
This chamber of the cochlea is associated with the oval window and filled with perilymph (similar to CSF).
Scala vestibuli
78
This chamber of the cochlea is filled with endolymph, which bathes the top of hair cells and is rich in K+.
Scala media
79
This chamber of the cochlea is associated with the round window and filled with perilymph, which bathes the lower bodies of hair cells.
Scala tympani
80
This structure separates the scala vestibuli from the scala media.
Reissner's membrane
81
These cells secrete endolymph into the scala media and actively transport K+.
Stria vascularis
82
An endocochlear potential between the endolymph and the perilymph is created due to the active transport of K+ into the endolymph. What is size of this potential?
+80 mV
83
What is the function of the cochlea?
To change mechanical vibrations in fluids to action potentials in C.N. VIII
84
Different sound frequencies displacing different areas of the basilar membrane. This is used to describe what term?
Place principle
85
Describe the hair cells near the oval window (base of the cochlea).
They are short, thick, and respond best to higher frequencies (>4500 Hz)
86
Describe the hair cells near the helicotrema (apex of the cochlea).
They are long, slender, and respond best to lower frequencies (<200 Hz)
87
Any complex wave can be broken down into its component sine waves with differing phases, frequencies, and amplitudes. What type of test can you use to do this?
Fourier analysis
88
Describe the central auditory pathway.
Organ of Corti--->ventral and dorsal cochlear nuclei in the upper medulla--->cochlear nerve---> superior olivary nucleus--->nucleus of the lateral lemniscus--->inferior colliculus--->medial geniculate nucleus--->primary auditory cortex
89
Where is the primary auditory complex located? What type of organization does it have?
- It is located in the superior gyrus of the temporal lobe
| - It has a tonotopic organization (high freq. in the posterior and low freq. in the anterior)
90
This conduction pathway involves the external ear canal, middle ear, and the inner ear
Air conduction pathway
91
This conduction pathway involves direct stimulation of the cochlea through the vibration of the skull.
Bone conduction pathway
92
During a Weber test, if the sound is louder in the bad ear what type of hearing deficiency is it?
Conduction loss in the bad ear (external canal or ossicles involved)
93
During a Weber test, if the sound is louder in the good ear what type of hearing deficiency is it?
Sensory neural loss in the bad ear
94
What test is used to confirm the Weber test?
Rinne test
- air conduction > bone-sensory neural
- bone conduction > air-air conduction loss
95
Sound localization is determined by what two principal mechanisms?
- Time lag between the ears (medial superior olivary nucleus)
- Difference in intensities of sounds in both ears (lateral superior olivary nucleus)
96
What is a sour taste caused by?
Acids (hydrogen ion concentration)
97
What is a salty taste caused by?
Ionized salts (primarily the [Na+])
98
What is a sweet taste caused by?
Most are organic chemicals (sugars, esters, glycols, alcohols, aldehydes, ketones, amides, amino acids) and inorganic salts of Pb and Be
99
What is a bitter taste caused by?
No one class of compounds but:
- long chain organic compounds with N
- alkaloids (quinine, strychnine, caffeine, nicotine)
100
What is an umami/savory taste caused by?
- Flavor is associated with MSG
| - Receptor responds to amino acids
101
These type of papillae in the tongue are blunt pegs with 1-5 buds/top.
Fungiform
102
These type of papillae in the tongue are submerged pegs in serous fluid with 1000's of taste buds on the side.
Foliate
103
These type of papillae in the tongue are stout central stalks in serous filled moats with taste buds on the sides in the fluid.
Cicrumvallate
104
What type of influence do taste nerves provide taste buds? It allows for the regeneration of receptors and buds when damaged.
Trophic influence
105
Is adaptation of taste fast or slow?
Fast
106
What is the innervation of the anterior 2/3 of the tongue?
Lingual nerve to chorda tympani to facial (C.N. VII)
107
What is the innervation of the posterior 1/3 of the tongue
C.N. IX (petrosal ganglion)
108
What is the innervation of the base of the tongue and palate?
C.N. X
109
Where do all of the taste pathways terminate?
Nucleus tractus solitarius (NTS)
110
From the nucleus tractus solitarius where does the taste pathway go?
To the VPM via the central tegmental tract--->lower tip of the post central gyrus (parietal cortex) and adjacent opercular insular area in the sylvian fissure
111
What ions are involved with bitter tastes? Sweet? Sour? Salty?
Bitter: calcium
Sweet: potassium
Sour: potassium
Salty: sodium
112
What tastes are associated with G protein linked receptors?
Bitter, sweet, and umami
113
What tastes are associated with ion channels?
Sour and salty
114
The nose contains 3 conchae, what are their functions?
- Moisten and warm incoming air
| - Limits loss of heat at H2O in expired air
115
What does "sniffing" do?
It increases the percentage of air around the conchae by creating more turbulence
116
This structure is located medially on the septum in the lower part of the nasal cavity, appears to contribute to olfaction, and is probably more receptive than olfactory epithelium to pheromones.
Vomernasal organ
117
This is the superior part of the nostril and contains olfactory cells.
Olfactory membrane
118
These are bipolar nerve cells which project hairs in mucus in the nasal cavity. They are stimulated by odorants and connect to the olfactory bulb via the cribiform plate.
Olfactory cells
119
These cells secrete mucus in the olfactory membrane.
Cells which make up Bowman's glands
120
These cells are supporting cells that are within the olfactory membrane.
Sustenacular cells
121
For odorants to be detected they must be what?
Volatile
122
For odorants to be detected in the mucus they must be what?
Slightly water soluble
123
For odorants to be detected in the membrane of cilia they must be what?
Slightly lipid soluble
124
What substance is added to natural gas so gas leaks can be detected?
Methyl mercaptan
125
What is the pathway of olfactory cell stimulation?
- Adenyl cyclase converts ATP to cAMP
- This causes protein gated Na+ channels to open
- Ca++ enters the cell and opens chloride channels resulting in a high Cl- concentration inside the cell.
126
This condition is often called odor blindness.
Anosmia
127
What does Cl- efflux do to olfactory receptors during stimulation?
It prolongs depolarization
128
These are connections between olfactory cells and cells of the olfactory tract. It is also a site of convergence for neurons.
Glomerulus in the olfactory bulb (does not contain cell bodies)
129
These two cell types within the olfactory bulb are continually active and send axons into the CNS via the olfactory tract.
Mitral and tufted cells
130
These cells within the olfactory bulb are inhibitory, can decrease neural traffic in the olfactory tracts, and receive input from centrifugal nerve fibers.
Granule cells
131
These cells within the olfactory bulb are inhibitory between the glomerulus.
Periglomerular cells
132
What is the very old CNS pathway of olfaction?
- It is the medial olfactory area and feeds into the hypothalmus and primitive areas of the limbic system (from medial pathway)
- It involves basic olfactory reflexes
133
What is the less old CNS pathway of olfaction?
- It is the lateral olfactory area and involves the prepyriform and pyriform cortex
- It is the only sensory pathway to the cortex that doesn't relay via the thalamus (from the lateral pathway)
- It involves learned control/adversion
134
What is the newer CNS pathway of olfaction?
- It passes through the thalamus to orbitofrontal cortex (from the lateral pathway)
- It is involved with conscious analysis of odor
135
Second order neurons form the olfactory tract and project to what primary olfactory paleocortical areas?
- Anterior olfactory nucleus
- Amygdala and olfactory tubercle
- Pyriform and periamygdaloid cortex
- Rostral entorhinal cortex
136
What is the anterior olfactory nucleus involved with?
It modulates information processing in olfactory bulbs
137
What is the amygdala and olfactory tubercle involved with?
It is important in emotional, endocrine, and visceral responses of odors
138
What is the pyriform and periamygdaloid cortex involved with?
Olfactory perception
139
What is the rostral entorhinal cortex involved with?
Olfactory memories
140
What do the medial and lateral pathways of olfaction use to communicate?
Anterior commissure
141
What is thought to cause odors evoking recollections of past experiences?
Direct penetration of the emotional areas of the limbic system by olfactory fibers
