Ch.8: Special Senses Flashcards
1
Q
Special senses include:
A
- Smell
- Taste
- Sight
- Hearing
- Equilibrium
2
Q
What are special sense receptors?
A
- Large, complex sensory organs
* Localized clusters of receptors
3
Q
Concept Link
A
Recall the three basic functions of the nervous system (Figure 7.1, p. 226). Each of the special senses gathers unique sensory information that, once integrated, will influence motor output. For example, if you saw a ball moving toward your head, this sensory input might result in a motor output that would move your body out of the path of the ball. Additionally, each type of sensory information is processed in a specialized area of the cerebrum. (Figure 7.13c, p. 242).
4
Q
70 percent of all sensory receptors are in the:
A
Eyes
5
Q
Each eye has over _____ nerve fibers carrying information to the brain
A
1 million
6
Q
Accessory structures of the eye include:
A
- Extrinsic eye muscles
- Eyelids
- Conjunctiva
- Lacrimal apparatus
7
Q
Where do eyelids meet?
A
At the medial and lateral commissure (canthus)
8
Q
What are the properties of eyelashes?
A
- Tarsal glands produce an oily secretion that lubricates the eye
- Ciliary glands are located between the eyelashes
9
Q
What is conjunctiva?
A
- Membrane that lines the eyelids and eyeball
- Connects with the transparent cornea
- Secretes mucus to lubricate the eye and keep it moist
10
Q
Lacrimal gland + ducts=
A
- Lacrimal apparatus
- Lacrimal gland—produces lacrimal fluid (tears); situated on lateral end of each eye
- Tears drain across the eye into the lacrimal canaliculi, then the lacrimal sac, and into the nasolacrimal duct, which empties into the nasal cavity
11
Q
Tears contain:
A
- Dilute salt solution
- Mucus
- Antibodies
- Lysozyme (enzyme that destroys bacteria)
12
Q
What are the function of tears?
A
Cleanse, protect, moisten, lubricate the eye
13
Q
What is the function of extrinsic eye muscles?
A
- Six muscles attach to the outer surface of the eye
* Produce gross eye movements
14
Q
What are the three layers, or tunics, which form the wall of the eyeball?
A
- Fibrous layer: outside layer
- Vascular layer: middle layer
- Sensory layer: inside layer
15
Q
_____ are fluids that fill the interior of the eyeball.
A
Humors
16
Q
_____ divides the eye into two chambers.
A
Lens
17
Q
Sclera + cornea=
A
Fibrous layer
18
Q
What is the sclera?
A
- White connective tissue layer
* Seen anteriorly as the “white of the eye”
19
Q
What is the cornea?
A
- Transparent, central anterior portion
- Allows for light to pass through
- Repairs itself easily
- The only human tissue that can be transplanted without fear of rejection
20
Q
What is the vascular layer of the eyeball?
A
• Choroid is a blood-rich nutritive layer that contains a pigment (prevents light from scattering)
• Choroid is modified anteriorly into two smooth muscle structures
*Ciliary body
*Iris
21
Q
What is and what is the function of the iris?
A
- Pigmented layer that gives eye color
- Regulates amount of light entering eye
- Pupil—rounded opening in the iris
22
Q
What is the sensory layer of the eyeball?
A
Retina contains two layers
1. Outer pigmented layer absorbs light and prevents it from scattering
2. Inner neural layer contains receptor cells (photoreceptors)
• Rods
• Cones
23
Q
Electrical signals pass from photoreceptors via what two-neuron chain in the sensory layer?
A
- Bipolar neurons
* Ganglion cells
24
Q
Signals leave the _____ toward the brain through the _____ in the sensory layer.
A
- Retina
* Optic nerve
25
_____ is where the optic nerve leaves the eyeball.
* Optic disc (blind spot)
| * Cannot see images focused on the optic disc
26
What is the function of rods in the sensory layer?
* Most are found toward the edges of the retina
* Allow vision in dim light and peripheral vision
* All perception is in gray tones
27
What is the function of cones in the sensory layer?
```
• Allow for detailed color vision
• Densest in the center of the retina
• Fovea centralis–lateral to blind spot
*Area of the retina with only cones
*Visual acuity (sharpest vision) is here
```
28
No photoreceptor cells are at the:
Optic disc, or blind spot
29
What is cone sensitivity?
* Three types of cones
| * Each cone type is sensitive to different wavelengths of visible light
30
What is a lens?
* Flexible, biconvex crystal-like structure
| * Held in place by a suspensory ligament attached to the ciliary body
31
The lens divides the eye into what two chambers?
* Anterior (aqueous) segment
| * Posterior (vitreous) segment
32
What is the anterior (aqueous) segment of the lens?
* Anterior to the lens
| * Contains aqueous humor, a clear, watery fluid
33
What is the posterior (vitreous) segment of the lens?
* Posterior to the lens
| * Contains vitreous humor, a gel-like substance
34
What is aqueous humor?
* Watery fluid found between lens and cornea
* Similar to blood plasma
* Helps maintain intraocular pressure
* Provides nutrients for the lens and cornea
* Reabsorbed into venous blood through the scleral venous sinus, or canal of Schlemm
35
What is vitreous humor?
* Gel-like substance posterior to the lens
* Prevents the eye from collapsing
* Helps maintain intraocular pressure
36
What is an opthalmoscope?
* Instrument used to illuminate the interior of the eyeball and fundus (posterior wall)
* Can detect diabetes, arteriosclerosis, and degeneration of the optic nerve and retina
37
What is the pathway of light through the eye and light refraction?
* Light must be focused to a point on the retina for optimal vision
* Light is bent, or refracted, by the cornea, aqueous humor, lens, and vitreous humor
* The eye is set for distant vision (over 20 feet away)
* Accommodation—the lens must change shape to focus on closer objects (less than 20 feet away)
38
Image formed on the retina is a:
• Real image
39
What are real images?
* Reversed from left to right
* Upside down
* Smaller than the object
40
What is the optic nerve?
Bundle of axons that exit the back of the eye carrying impulses from the retina
41
What is the optic chiasma?
* Location where the optic nerves cross
| * Fibers from the medial side of each eye cross over to the opposite side of the brain
42
What are optic tracts?
* Contain fibers from the lateral side of the eye on the same side and the medial side of the opposite eye
* Synapse with neurons in the thalamus
43
What is optic radiation?
* Axons from the thalamus run to the occipital lobe
| * Synapse with cortical cells, and vision interpretation (seeing) occurs
44
Summary of the pathway of impulses from the retina to the point of visual interpretation
1. Optic nerve
2. Optic chiasma
3. Optic tract
4. Thalamus
5. Optic radiation
6. Optic cortex in occipital lobe of brain
45
What is referred to as visual fields?
* Each eye “sees” a slightly different view
| * Field of view overlaps for each eye
46
Binocular vision results and provides:
Depth perception (three-dimensional vision)
47
What is emmetropia?
Eye focuses images correctly on the retina
48
What is myopia?
* Nearsightedness
* Distant objects appear blurry
* Light from those objects fails to reach the retina and are focused in front of it
* Results from an eyeball that is too long
49
What is hyperopia?
* Farsightedness
* Near objects are blurry, whereas distant objects are clear
* Distant objects are focused behind the retina
* Results from an eyeball that is too short or from a “lazy lens”
50
What is astigmatism?
* Images are blurry
| * Results from light focusing as lines, not points, on the retina because of unequal curvatures of the cornea or lens
51
What are the types of eye reflexes?
* Convergence
* Photopupillary reflex
* Accommodation pupillary reflex
52
What is convergence?
Reflexive movement of the eyes medially when we focus on a close object
53
What is photopupillary reflex?
Bright light causes pupils to constrict
54
What is accommodation pupillary reflex?
Viewing close objects causes pupils to constrict
55
The ear houses what two senses?
1. Hearing
| 2. Equilibrium (balance)
56
Receptors in the ear are:
* Mechanoreceptors
| * Different organs house receptors for each sense
57
The ear is divided into what three areas?
External (outer) ear
Middle ear
Internal (inner) ear
58
What are the components and function of the external ear?
* Auricle (pinna)
* External acoustic meatus (auditory canal)
* External ear is involved only in collecting sound waves
59
What is the external acoustic meatus (auditory canal)?
* Narrow chamber in the temporal bone
* Lined with skin and ceruminous (earwax) glands
* Ends at the tympanic membrane (eardrum)
60
What is the middle ear cavity?
* Tympanic cavity
* Air-filled, mucosa-lined cavity within the temporal bone
* Involved only in the sense of hearing
* Located between tympanic membrane and oval window and round window
61
What are the three bones (ossicles) which span the middle ear cavity (tympanic cavity)?
1. Malleus (hammer)
2. Incus (anvil)
3. Stapes (stirrup)
62
What is the function of the middle ear cavity (tympanic cavity)?
* Transmit vibrations from tympanic membrane to the fluids of the inner ear
* Vibrations travel from the hammer → anvil → stirrup → oval window of inner ear
63
What are the components of the internal ear?
* Includes sense organs for hearing and balance
| * Bony labyrinth (osseous labyrinth)
64
Bony labyrinth (osseous labyrinth) consists of:
* Cochlea
* Vestibule
* Semicircular canals
65
Bony labyrinth is filled with:
* Perilymph
| * Membranous labyrinth is suspended in perilymph and contains endolymph
66
Equilibrium receptors of the inner ear are called the:
Vestibular apparatus
67
Vestibular apparatus has what two functional parts?
1. Static equilibrium
| 2. Dynamic equilibrium
68
What are maculae of the static equilibrium?
* Receptors in the vestibule
* Report on the position of the head
* Help us keep our head erect
* Send information via the vestibular nerve (division of cranial nerve VIII) to the cerebellum of the brain
69
What is the anatomy of the maculae?
* Hair cells are embedded in the otolithic membrane
* Otoliths (tiny stones) float in a gel around hair cells
* Movements cause otoliths to roll and bend hair cells
70
What is the crista ampullaris?
* Responds to angular or rotational movements of the head
* Located in the ampulla of each semicircular canal
* Tuft of hair cells covered with cupula (gelatinous cap)
* If the head moves, the cupula drags against the endolymph
* Hair cells are stimulated, and the impulse travels the vestibular nerve to the cerebellum
71
What is the spiral organ of Corti?
* Located within the cochlear duct
* Receptors = hair cells on the basilar membrane
* Gel-like tectorial membrane is capable of bending hair cells
* Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on temporal lobe
72
What is the pathway of vibrations from sound waves?
* Move by the ossicles from the eardrum to the oval window
* Sound is amplified by the ossicles
* Pressure waves cause vibrations in the basilar membrane in the spiral organ of Corti
* Hair cells of the tectorial membrane are bent when the basilar membrane vibrates against it
* An action potential starts in the cochlear nerve (cranial nerve VIII), and the impulse travels to the temporal lobe
73
High-pitched sounds disturb the _____ fibers of the basilar membrane.
* Short, stiff
| * Receptor cells close to the oval window are stimulated
74
Low-pitched sounds disturb the _____ fibers of the basilar membrane.
* Long, floppy
| * Specific hair cells further along the cochlea are affected
75
Deafness is any degree of:
* Hearing loss
* Conduction deafness results when the transmission of sound vibrations through the external and middle ears is hindered
* Sensorineural deafness results from damage to the nervous system structures involved in hearing
* Ménière’s syndrome affects the inner ear and causes progressive deafness and perhaps vertigo (sensation of spinning)
76
What are chemoreceptors?
* Stimulated by chemicals in solution
* Taste has five types of receptors
* Smell can differentiate a wider range of chemicals
77
Both senses of smell and taste _____ each other and respond to many of the same _____.
* Complement
| * Stimuli
78
Olfactory receptors are in roof of the:
Nasal cavity
79
Olfactory receptor cells (neurons) with long cilia known as olfactory hairs detect:
Chemicals
80
Chemicals must be dissolved in mucus for detection by chemoreceptors called:
Olfactory receptors
81
Impulses are transmitted via the olfactory filaments to the:
Olfactory nerve (cranial nerve I)
82
Smells are interpreted in the:
Olfactory cortex
83
Taste buds house the:
Receptor organs
84
What are the locations of taste buds?
* Most are on the tongue
* Soft palate
* Superior part of the pharynx
* Cheeks
85
The tongue is covered with projections called _____ that contain _____.
Papillae
| Taste buds
86
What are the three types of papillae that are found on the tongue?
1. Vallate (circumvallate) papillae
2. Fungiform papillae
3. Filiform papillae
87
Gustatory cells are the:
* Taste receptors
* Possess gustatory hairs (long microvilli)
* Gustatory hairs protrude through a taste pore
* Hairs are stimulated by chemicals dissolved in saliva
88
Impulses are carried to the _____ by several _____ because taste buds are found in different areas.
* Gustatory complex
* Cranial nerves
* Facial nerve (cranial nerve VII)
* Glossopharyngeal nerve (cranial nerve IX)
* Vagus nerve (cranial nerve X)
89
Taste buds are replaced frequently by:
Basal cells
90
What are the five basic taste sensations?
* Sweet receptors
* Sour receptors
* Bitter receptors
* Salty receptors
* Umami receptors
91
Sweet receptors respond to:
* Sugars
* Saccharine
* Some amino acids
92
Sour receptors respond to:
H+ ions or acids
93
Bitter receptors respond to:
Alkaloids
94
Salty receptors respond to:
Metal ions
95
Umami receptors respond to the amino acid:
Glutamate or the beefy taste of meat
96
Special sense organs are formed early in:
Embryonic development
97
Maternal infections during the first 5 or 6 weeks of pregnancy may cause _____ as well as _____ in the developing child.
* Visual abnormalities
| * Sensorineural deafness
98
Vision requires the most:
Learning
99
The infant has poor _____ and lacks _____ and _____ at birth
* Visual acuity (is farsighted)
* Color vision
* Depth perception
100
The eye continues to grow and mature until age:
8 or 9
101
What are age-related eye issues?
• Presbyopia—“old vision” results from decreasing lens elasticity that accompanies aging
*Causes difficulty to focus for close vision
• Lacrimal glands become less active
• Lens becomes discolored
• Dilator muscles of iris become less efficient, causing pupils to remain constricted
102
The newborn infant can hear sounds, but initial responses are:
Reflexive
103
By the toddler stage, the child is _____ and beginning to _____ as language development begins.
* Listening critically
| * Imitate sounds
104
What are age-related ear problems?
Presbycusis—type of sensorineural deafness that may result from otosclerosis
• Otosclerosis—ear ossicles fuse
Congenital ear problems usually result from missing pinnas and closed or missing external acoustic meatuses
105
Taste and smell are most acute at birth and decrease in sensitivity after age __ as the number of _____ and _____ receptors decreases
* 40
* Olfactory
* Gustatory
