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
