Special Senses Flashcards
What convert a specific stimulus into action potentials?
Sensory neuron endings
Processing of sensory signals gives rise to ___.
Sensation
The awareness of a stimulus
Sensation
True or False: A strong stimulus causes a receptor to generate potentials more often and longer than a weak signal.
TRUE
True or False: A weak signal signal recruits more sensory receptors compared to a strong stimulus.
FALSE. A strong stimulus recruits more sensory receptors compared to a weak stimulus.
True or False: The duration of a stimulus affects how the stimulus is interpreted.
TRUE
Sensory neurons stop generating action potentials, or make fewer of them, despite continued stimulation.
Sensory adaptation
Arises when the brain assigns meaning to sensory signals.
Sensory perception
You notice a sweet scent of apple pie, but within a few minutes, the scent seems to lessen. This is an example of ___.
Sensory adaptation
The odor does not change in intesity,but the chemoreceptors in your nose adapt to it.
When a person walk away from you, the image of the person becomes smaller. You perceive this change in sensation as evidence of increasing distance between you and the person, rather than the person shrinking. This is an example of ___.
Sensory perception
What are the five special senses?
Smell, taste, sight, hearing, balance
Olfaction is also known as ___.
Smell
Gustation is also known as ___.
Taste
Vision is also known as ___.
Sight
Audition is also known as ___.
Hearing
Balance is also called ___.
Equilibrium
70% of all sensory receptors are found where?
The eyes
Each eye has how many nerve fibers?
Over 1 million
Most of the eye is enclosed in a ___.
Bony orbit
A ____ surrounds most of the eeye.
Cushion of fat
What are the accessory structures of the eye?
Eyelids and eyelashes
Conjunctiva
Lacrimal apparatus
Extrinsic eye muscles
Lacrimal apparatus is involved in what process?
Tear production
Skeletal muscles that innervate eye movement.
Extrinsic eye muscles
The eyelids meet at the medial and lateral commissure known as ___.
Canthus
Produce an oily secretion that lubricates the eye.
Tarsal gland
Located between the eyelashes.
Ciliary glands
Membrane that lines the eyelids.
Conjunctiva
Where does the conjunctiva connect?
Outer surface of the eye
The conjunctiva secretes ___ to lubricate the eye and keep it moist.
Mucus
What does the conjunctiva cover?
Sclera
An inflamed conjunctiva will result in ____.
Pinkeye or bacterial conjunctivitis.
Protects, moistens, and lubricates the eye
Lacrimal apparatus
The lacrimal apparatus empties into which cavity?
Nasal cavity
The lacrimal apparatus is comprised of ___.
Lacrimal glands and ducts (lacrimal canaliculi, lacrimal sac, nasolacrimal duct)
Produces lacrimal fluid
Lacrimal gland
The lacrimal gland is situated on the ___ aspect of each eye.
Lateral
Drain lacrimal fluid from eyes medially.
Lacrimal canaliculi
Provides passage of lacrimal fluid towards nasal cavity.
Lacrimal sac
Empties lacrimal fluid into the nasal cavity.
Nasolacrimal duct
True or False: A portion of nasal mucus is tears.
TRUE. Tears draining through the nasolacrimal duct can end up in the nasal mucus, which is why we tend to blow our nose when we cry.
Lacrimal secretions are commonly known as ___.
Tears
Lacrimal secretions contain ___.
Dilute salt solution
Mucus
Antibodies (immunoglobulin A)
Lysozyme (enzyme that destroys bacteria)
Where to extrinsic eye muscles attach?
Outer surface of the eye
Produce eye movement.
Extrinsic eye movements
How many extrinsic eye muscles are there?
Six
What are the extrinsic eye muscles?
Lateral rectus
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
Superior oblique
The extrinsic eye muscles are innervated by which cranial nerves?
Oculomotor (III)
Trochlear (IV)
Abducens (VI)
The ___ moves the eye laterally, and is innervated by cranial nerve ___.
Lateral rectus; VI (abducens)
The ____ moves the eye medially, and is innervated by cranial nerve ___.
Medial rectus; III (oculomotor)
The ___ elevates the eye and turns it medially, and is innervated by cranial nerve ___.
Superior rectus; III (oculomotor)
The ___ depresses the eye and turns it medially, and is innervated by cranial nerve ___.
Inferior rectus; III (oculomotor)
The ___ elevates the eye and turns it laterally, and is innervated by cranial nerve ___.
Inferior oblique; III (oculomotor)
The ___ depresses the eye and turns it laterally, and is innervated by cranial nerve ___.
Superior oblique; IV (trochlear)
What are the layers that form the wall of the eyeball from outermost to innermost?
Fibrous layer
Vascular layer
Sensory layer
Fluids that fill the interior of the eyeball.
Humor
What are the structures in the fibrous layer of the eye?
Sclera and cornea
White connective tissue layer seen anteriorly as the “white of the eye”
Sclera
Transparent, central anterior portion that allows for light to pass through
Cornea
True or False: The cornea can repair itself easily because it is highly vascular.
FALSE. The cornea can repair itself easily, but it is avascular
The cornea traps ___ from the environment.
Oxygen
The only human tissue that can be transplanted without rejection
Cornea
Blood-rich nutritive layer in the posterior of the eye.
Choroid
___ in the choroid prevents the light from scattering.
Pigment
The choroid is modified anteriorly into what two structures?
Ciliary body and iris
Smooth muscle attached to lens
Ciliary body
The ciliary body is attached to the lens by a suspensory ligament called ___.
Ciliary zonule
Regulates the amount of light entering the eye
Iris
What gives the eye color?
Pigmented layer of the iris
Rounded opening in the iris
Pupil
What are the two layers of the retina?
Outer pigmented layer
Inner neural layer
This layer of the retina absorbs light and prevents it from scattering.
Outer pigmented layer
The inner neural layer contains receptor cells known as ___.
Photoreceptors
What are the two types of photoreceptors?
Rods and cones
Signals pass from photoreceptors via ____.
Two-neuron chain
What are the two neurons involved in the two-neuron chain of photoreceptors?
Bipolar neurons and ganglion cells
Signals leave the retina toward the brain through the ___.
Optic nerve
It is where the optic nerve leaves the eyeball.
Optic disc
The optic disc is commonly called the ___.
Blind spot
True or False: You cannot see images focused on the optic disc.
TRUE. This is why it is also called the blind spot.
Most rods are found toward the ___ of the retina.
Edges
Rods allow for vision in ___.
Dim light and peripheral vision
All perception of rods are in ___ tones.
Gray
Allow for detailed color vision
Cones
Cones are densest in the ___ of the retina.
Center
Area of the retina with only cones; sharpest vision is here.
Fovea centralis
Where is the fovea centralis located?
Lateral to the blind spot
True or False: No photoreceptor cells are at the optic disc.
TRUE
What are the three types of cones?
Blue, green, and red
True or False: different cones are sensitive to different wavelengths.
TRUE
It is the result of the lack of one cone type.
Color blindness
___ cones are the most prominent in terms of wavelength, while ____ cones are least prominent.
Red; blue
The lens has a ____ structure.
biconvex, crystal-like structure
The lens is held in place by a ___.
Suspensory ligament attached to the ciliary body.
Results when the lens becomes hard and opaque with age.
Cataract (opacity of lens)
What are the effects of a cataract?
Hazy and distorted vision, eventual blindness in affected eye
What are the risk factors for a cataract?
Diabetes mellitus
Frequent exposure to intense sunlight
Heavy smoking
The lens divides the eye into what two chambers?
Anterior (aqueous) segment and posterior (vitreous) segment
The anterior segment is ___ to the lens and contains ___ humor.
Anterior; aqueous
The posterior segment is ____ to the lens and contains ___ humor.
Posterior; vitreous
Watery fluid found between lens and cornea.
Aqueous humor
The composition of aqueous humor is similar to that of ___.
Blood plasma
Aqueous humor provided nutrients for the ____.
Lens and cornea
Aqueous humor is reabsorbed into venous blood through the ____.
Scleral venous sinus or canal of Schlemm
Gel-like substance posterior to the lens that prevents the eye from collapsing.
Vitreous humor
Aqueous and vitreous humor help maintain ___.
Intraocular pressure (IOP)
Instrument used to illuminate the interior of the eyeball and fundus.
Ophthalmoscope
Posterior wall of the eye
Fundus
What can the ophthalmoscope detect?
Diabetes, arteriosclerosis, and degeneration of the optic nerve and retina
Light must be focused to a pointon the ____ for optimal vision.
Retina
Light is ____ by the cornea, aqueous humor, lens, and vitreous humor.
Bent or refracted
The eye is set for ____ vision (over 20 feet away).
Distance
The lens changes shape to focus on closer objects (less than 20 feet away).
Accommodation
Image formed on the retina is a ___.
Real image
Real images are ___.
Reversed from left to right
Upside down
Smaller than the object
What is the pathway of light through the eye?
Cornea
Aqueous humor
Through pupil
Aqueous humor
Lens
Vitreous humor
Retina
Location where the optic nerves cross
Optic chiasma
True or False: Images perceived by the right eye proceed to the left part of the brain, and vice versa.
TRUE. Fibers from the medial side of the eye cross over to the opposite side of the brain.
Contain fibers from the lateral side of the eye on the same side and the medial side of the opposite eye.
Optic tracts
Overlap of the visual fields and inputs from both eyes to each optic cortex in the occipital lobe provide for ____.
Depth perception
What is the pathway of nerve impulses into the brain?
Optic nerve
Optic chiasma
Optic tract
Thalamus
Optic radiation
Visual cortex in occipital lobe of the brain
Internal eye muscles are controlled by the ____ nervous system.
Autonomic
Bright light causes pupils to constrict through action of radial, circular, and ciliary muscles.
Photopupillary reflex
Viewing close objects causes accommodation in what reflex?
Accommodation pupillary reflex
Viewing close objects causes _____.
Convergence (eyes move medially)
Eye focuses images correctly on the retina.
Emmetropia (normal vision)
Distant objects appear blurry, light from those objects fail to reach the retina and are focused in front of it.
Myopia (near-sightedness)
Myopia results from an eyeball that is ___.
Too long
Near objects are blurry, whereas distant objects are clear; distant objects are focused behind the retina.
Hyperopia (far-sightedness)
Hyperopia results from an eyeball that is ___.
Too short or a “lazy lens”
Results from light focusing as lines, not points, on the retina because of unequal curvatures of the cornea or lens.
Astigmatism
A myopic eye is usually corrected with a ____ lens, while a hyperopic eye is corrected with a ____ lens.
concave; convex
An emmetropic eye has no need for correction.
Inhibited rod function the ability to see at night.
Nyctalopia (night blindness)
Development of night blindness is associated with a deficiency of what vitamin?
Vitamin A (necessary for production of rods)
Genetic conditions that result in the inability to see certain colors.
Color blindness
Caused by the lack of one type of cone.
Partial color blindness
Can cause blindness due to increasing pressure within the eye.
Glaucoma
Iris blocks the drainage angle in the eye; trapped fluid inside the eye causes pressure to build up.
Closed-angle glaucoma
Drainage channels are open, but do not drain fluid properly.
Open-angle glaucoma
Loss of the same side of the visual field of both eyes.
Hemianopia
True or False: Hemianopia results from damage to the visual cortex of both eyes.
FALSE. It results from damage to the visual cortex on one side only.
The ear houses which two senses?
Hearing (Audition)
Equilibrium (Balance)
Receptors in the ear are called ____.
Mechanoreceptors
True or False: Different organs houses receptors for each sense.
TRUE
The ear is divided into what three areas?
External ear
Middle ear
Inner ear
The external ear is also called the ___.
Outer ear
The middle ear is also known as the ____
Tympanic cavity
The inner ear is also known as the ____.
Bony labyrinth
True or False: The external and middle ear are involved in hearing and equilibrium.
FALSE. They are involved in hearing only.
What are the structures of the external ear?
Auricle and external acoustic meatus
The auricle is also known as ____.
Pinna
The external auditory meatus is also known as ___.
Auditory canal
Directs sound waves to the external acoustic meatus.
Auricle
Narrow chamber in the temporal bone.
External auditory meatus
The auditory canal is lined with ____.
Skin and ceruminous (wax) glands
Where does the auditory canal end?
Tympanic membrane
Air-filled cavity within the temporal bone.
Middle ear (tympanic cavity)
Where is the tympanic cavity located?
Between the tympanic membrane and oval window and round window
What are the two tubes of the middle ear that are associated with the inner ear?
Opening from the auditory canal
Pharyngotympanic (auditory) tube
The opening from the auditory canal is covered by the ____.
Tympanic membrane
The pharyngotympanic tube connects the middle ear with the ___.
Throat (pharynx)
Allows for equalizing pressure during yawning or swallowing.
Pharyngotympanic tube
True or False: When not yawning or swallowing, the pharyngotympanic tube is collapsed.
TRUE.
What three bones span the tympanic cavity?
Malleus
Incus
Stapes
The malleus, incus, and stapes are collectively called ___.
Ossicles
The malleus is also called ___.
Hammer
The incus is also called ___.
Anvil
The stapes is also called ___.
Stirrup
The inner ear includes sense organs for what two senses?
Hearing and equilibrium
The inner ear is filled with ____.
Perilymph
The tympanic membrane is also known as ___.
Eardrum
What comprises the maze of bony chambers within the temporal bone?
Cochlea
Vestibule
Semicircular canals
The membranous labyrinth is suspended in ____ and contains ____.
perilymph; endolymph
The eardrum serves as a boundary between the ___ and ___.
Outer and middle ear
What are the tiniest bones in the body?
Ossicles (malleus, incus, stapes)
What connects the middle ear and the nasal cavity?
Pharyngotympanic tube
Equilibrium receptors of the inner ear are called ___.
Vestibular apparatus.
What are the two functional parts of equilibrium?
Static equilibrium
Dynamic equilibrium
Receptors in the vestibule
Macula/maculae
The maculae report on the position of the ___.
Head
True or False: Even if we extend, flex, or turn our head to the side, our body is able to maintain equilibrium.
TRUE. This is known as static equilibrium.
The maculae send information via the ____.
Vestibular nerve
Hair cells in the maculae are embedded in the ___.
Otolithic membrane
____ float in a gel around the hair cells.
Otoliths (tiny stones)
Movements cause otoliths to ___ the hair cells.
Bend
These receptors respond to angular or rotary movements.
Dynamic equilibrium receptors
Dynamic equilibrium receptors located in the semicircular canals
Crista ampullaris
Where are the crista ampullaris located?
In the ampulla of each semicircular canal
In the crista ampulla, there are tufts of hair cells covered with a gelatinous cup known as ___.
Cupula
If the head moves, the cupula drags against the ___.
Endolymph
What stimulates the hair cells in dynamic equilibrium?
Movement of the cupula
In dynamic equilibrium, an impulse is sent via the ____ to the ____.
Vestibular nerve; cerebellum
What is the organ of hearing?
Spiral organ of Corti
Where is the spiral organ of Corti located?
Within the cochlear duct
What are the receptors for the spiral organ of corti?
Hair cells on the basilar membrane
What gel-like membrane is capable of bending hair cells?
Tectorial membrane
What transmits auditory nerve impulses to the brain?
Cochlear nerve
The cochlear nerve transmits nerve impulses to which part of the brain?
Auditory cortex of the temporal lobe
___ disturb the short, stiff fibers of the basilar membrane.
High-pitch sounds
What are stimulated by high-pitch sounds?
Receptor cells close to the oval window
___ disturb the long, floppy fibers of the basilar membrane.
Low-pitch sounds
What are affected by low-pitch sounds?
Specific hair cells further along the cochlea
It is any degree of hearing loss.
Deafness
This type of deafness results when the transmission of sound vibrations through the external & middle ears is hindered.
Conduction deafness
This type of deafness results from damage to the nervous system structures involved in hearing.
Sensorineural deafness
This disease affects the inner ear and causes progressive deafness and perhaps vertigo and tinnitus.
Meniere’s Syndrome
What type of receptors are used to detect smell and taste?
Chemoreceptors
What stimulates chemoreceptors?
Chemicals in solution (in food or in the air)
How many types of receptors does taste have?
Four
True or False: Taste and smell are usually complementary and respond to many of the same stimuli.
TRUE
What receptors can be found in the roof of the nasal cavity?
Olfactory receptors
Olfactory receptor cells with long cilia known as ___ detect chemicals.
Olfactory hairs
Chemicals must be dissolved in mucus for detection by chemoreceptors called ___.
Olfactory receptors
Impulses are transmitted via the ___ to the olfactory nerve.
Olfactory filaments
Interpretation of smells is made in the ___.
Cortex
What houses the taste receptor organs?
Taste buds
Where are taste buds located?
Soft palate, cheeks, tongue
The tongue is covered with projections called ___.
Papillae
What are the three types of papillae?
Filiform papillae
Fungiform papillae
Circumvallate papillae
Sharp papillae with no taste buds
Filiform papillae
Round papillae with taste buds
Fungiform papillae
Large papillae with taste buds
Circumvallate papillae
Where on the papillae can taste buds be found?
On the sides of the papillae
What are the receptors for taste?
Gustatory cells
Gustatory cells possess long microvilli called ___.
Gustatory hairs
Gustatory hairs are stimulated by ___.
Chemicals dissolved in saliva
What cranial nerves carry impulses to the gustatory complex?
VII (Facial)
IX (Glossopharyngeal)
X (Vagus)
Taste buds are replaced frequently by ___.
Basal cells
What are the five types of gustatory receptors?
Sweet, sour, bitter, salty, umami
These gustatory receptors respond to sugars, saccharine, and some amino acids.
Sweet receptors
These gustatory receptors respond to H+ ions or acids.
Sour receptors
These gustatory receptors respond to alkaloids.
Bitter receptors
These gustatory receptors respond to metal ions.
Salty receptors
These gustatory receptors respond to the amino acid glutamate or the beefy taste of meat.
Umami receptors
True or False: Special sense organs are formed late in embryonic development.
FALSE. They are formed early in embryonic development.
Congenital ear problems usually result from ___.
Missing pinnas and closed or missing externa acoustic meatus
What sense requires the most learning?
Vision
True or False: The infant is farsighted and lacks color vision and depth perception at birth.
TRUE
The eye continues to grow and mature util what ages?
8 or 9
Results from unequal pulls by the external eye muscles in babies.
Strabismus
Strabismus is commonly called ___.
“Crossed eyes”
Conjunctivitis resulting from gonorrhea in the mother; baby’s eyelids are swollen, and pus is produced.
Ophthalmia Neonatorum
“Old vision” results from decreasing lens elasticity that accompanies aging.
Presbyopia
True or False: The newborn infant can hear sounds, but initial responses are reflexive.
TRUE
Hardening of ossicles
Otosclerosis
Type of sensorineural deafness that may result from otosclerosis
Presbycusis
What senses are the most acute at birth and decrease in sensitivity with age?
Taste and smell
