The only special sense not fully functional at birth is the sense of ________.
vision
Most newborns ________.
often use only one eye at a time
The first vestiges of eyes in the embryo are called ________.
optic vesicles
Nutrients are delivered and waste products are carried away from the cells of the posterior segment of the eye by blood vessels. However, the cells in the cornea and lens (in the anterior segment) are avascular. Which is the best explanation for how these
The aqueous humor is continuously replenished and flows from the ciliary process to drain in the scleral venous sinus.
The blind spot of the eye is caused by ________.
there are no photoreceptors where the optic nerve leaves the eye
Ordinarily, it is not possible to transplant tissues from one person to another, yet corneas can be transplanted without tissue rejection. This is because the cornea ________.
has no blood supply
What prevents the eyelids from sticking together when the eyes close?
tarsal gland secretions
Which of the following could not be seen as one looks into the eye with an ophthalmoscope?
optic chiasma
The tarsal plate of the eyelid ________.
is connected to the levator palpebrae
The eye muscle that elevates and turns the eye laterally is the ________.
inferior oblique
Damage to the medial rectus muscles would probably affect ________.
convergence
Seventy percent of all sensory receptors are located in the ________.
eye
The elasticity of the lens decreases with age. This leads to which of the following?
less accommodation of the lenses and difficulty focusing on nearby objects
The ability to clearly see objects at a distance but not close up is properly called ________.
hyperopia
What structure regulates the amount of light passing to the visual receptors of the eye?
iris
Light passes through the following structures in which order?
cornea, aqueous humor, lens, vitreous humor
Visible light fits between ________.
UV and infrared
In a person who is color blind, which of the following would you most expect to see?
absence of green or red cones in their foveae
Which of the following is the best explanation of why it is difficult to discriminate the color of an object at night?
Rods contain a single kind of visual pigment.
Which of the following is the best explanation for why night vision is fuzzy and indistinct?
The foveae are densely packed with cones.
Which of the following is the best explanation for our perception of color?
Cones come in three types, each sensitive to different wavelengths of light.
Photoreceptors are modified neurons. However, they differ from most neurons in the fact that ________.
photoreceptors will hyperpolarize when stimulated
Select the statement below that is not true with regards to the process of light adaptation.
Visual acuity is diminished.
Humans can see several thousand shades of color but have cone photoreceptors that are sensitive to only three (perhaps four) wavelengths of light. What is the best explanation for why we see so many colors?
Color perception is achieved by activation of various combinations between the three cone types.
Color vision has much greater resolution than night vision (vision that is mostly in shades of gray). Which of the following is the best explanation for why this is so?
A single cone photoreceptor often connects to a single bipolar cell and a single ganglion cell while as many as 100 rods will converge to a single ganglion cell.
What is the main function of the rods in the eye?
vision in dim light
There are three layers of neurons in the retina. The axons of which of these neuron layers form the optic nerves?
ganglion cells
Dark adaptation ________.
involves accumulation of rhodopsin
The cells of the retina in which action potentials are generated are the ________.
ganglion cells
During dark adaptation ________.
rhodopsin accumulates in the rods
Which of the following is true about photoreceptors?
Rods absorb light throughout the visual spectrum but confer only gray tone vision.
Overlap in the visual fields of our eyes ________.
allows us to subconsciously estimate the distance of objects based on the different angles the image strikes our two retinas
If you shine a light into one eye both pupils will constrict. The best explanation for this is ________.
sensory input from the retinas of both eyes converges at the optic chiasm and information from each eye is delivered to both the left and right sides of the brain
Nerve fibers from the medial aspect of each eye ________.
cross over to the opposite side at the chiasma
The first "way station" in the visual pathway from the eye, after there has been partial crossover of the fibers in the optic chiasma, is the ________.
lateral geniculate body of the thalamus
Another name for the primary visual cortex is ________.
striate cortex
Conscious perception of vision probably reflects activity in the ________.
occipital lobe of the cortex
In the visual pathways to the brain, the optic radiations project to the ________.
primary visual cortex
Visual inputs to the ________ serve to synchronize biorhythms with natural light and dark.
suprachiasmatic nucleus
Visual processing in the thalamus does not contribute significantly to ________.
night vision
Humans can smell as many as 10,000 different odors but have significantly fewer types of olfactory receptors. Which of the following is the best explanation for why humans can distinguish so many smells?
The sensation of a single, distinct smell is a combination of a variety of chemicals that stimulate different combinations of olfactory receptor cells all at once.
Olfactory cells and taste buds are normally stimulated by ________.
substances in solution
Which of the follow types of neurons are replaced throughout adult life?
olfactory receptor cells
Which of the following is not a characteristic of olfactory receptor cells?
They are unipolar neurons.
Flavor preferences, our likes and dislikes are said to have a "homeostatic value". Which of the following is the best example of this homeostatic value for taste preferences?
Alkaloids are chemical compounds in plants that are frequently toxic "antifeedant" chemicals. Alkaloids are often unpleasantly bitter.
Which of the following is true about gustatory receptors?
Complete adaptation occurs in about one to five minutes.
Taste buds are not found ________.
in filiform papillae
Select the correct statement about olfaction.
Some of the sensation of olfaction is actually one of pain.
Which of the following taste sensations is incorrectly matched to the chemicals that produce it?
umami-triglycerides and fatty acids
The receptor membranes of gustatory cells are ________.
gustatory hairs
Bitter taste is elicited by ________.
alkaloids
What is a modiolus?
a bone pillar in the center of the cochlea
Ceruminous glands are ________.
modified apocrine sweat glands
Which of the following structures is not part of the external ear?
pharyngotympanic tube
The oval window is connected directly to which passageway?
scala vestibuli
As sound levels increase in the spiral organ (of Corti), ________.
outer hair cells stiffen the basilar membrane
Receptors for hearing are located in the ________.
cochlea
Which pairing of terms is incorrectly related?
frequency of sound waves: loudness of the sound
The sensation of loudness or the volume of a sound is detected by ________.
greater movement of the basilar membrane resulting in greater deflection of the hair cells
A patient has a loss of hearing in only one ear. Which of the following is likely to be a result?
The patient will not be able to localize the origin of sounds.
Tom is a 45-year-old male that has lost his ability to hear high frequency sounds. The most likely explanation for this would be ________.
damage to the hair cells near the oval window in the cochlear duct
Which statement about sound localization is not true?
It requires processing at the cortical level.
Labyrinthitis is a medical condition often caused by viral infection, resulting in swelling and inflammation of the membranous labyrinth. Which of the following symptoms would you most associate with the condition of labyrinthitis?
loss of balance and dizziness
Dancers will use a technique called "spotting" when they perform spins of the body. By holding their head and eyes on a fixed point in front of them as their body spins they reduce the amount of head spinning and this prevents dizziness. Which of the foll
Reducing the inertia of head spin will reduce the flow of endolymph that deflects the hair cells of the crista ampullaris.
Information from balance receptors goes directly to the ________.
brain stem reflex centers
Motion sickness seems to ________
result from mismatch between visual and vestibular inputs
An essential part of the maculae involved in static equilibrium is (are) the ________.
otoliths
Select the correct statement about equilibrium.
Cristae respond to angular acceleration and deceleration.
The receptor for static equilibrium is the ________.
macula
Which statement about malnutrition-induced night blindness is most accurate?
Vitamin supplements can reverse degenerative changes.
Tinnitus, vertigo, and gradual hearing loss typify the disorder called ________.
M�ni�re's syndrome
Which of the following is not a possible cause of conduction deafness?
cochlear nerve degeneration