Question 1

In a person who is color-blind, which of the following would you most expect to see?

Accepted Answer

Color-blindness is a genetic condition that affects the red or green color receptors in the retina. This is often due to an absence of red or green cones in the fovea, which are responsible for detecting and interpreting color. As a result, individuals with color-blindness have difficulty distinguishing between certain colors, particularly those that are on the red/green spectrum.

Question 2

Hair cells in the spiral organ of the ear are never replaced.

Accepted Answer

Hair cells in the spiral organ of the ear can regenerate to a certain extent, but the extent and success of regeneration varies depending on the species and location within the cochlea. In humans, hair cell regeneration is limited and often insufficient to fully restore hearing loss.

Question 3

Which of the following best describes the function of the iris?

Accepted Answer

The iris is responsible for controlling the amount of light entering the eye by adjusting the size of the pupil. This allows for proper regulation of the amount of light that reaches the retina.

Question 4

Overlap in the visual fields of our eyes .

Accepted Answer

The 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. This is known as binocular disparity and is a key mechanism for depth perception. Additionally, the brain can combine information from both eyes to enhance stereopsis (the perception of depth and 3D structure). Therefore, it is not a waste of brain processing and does not increase visual acuity. While a blind spot does exist in the visual field, it is not significant enough to affect overall vision.

Question 5

The elasticity of the lens decreases with age. This leads to which of the following?

Accepted Answer

The decrease in elasticity of the lens with age leads to reduced ability of the lens to change its shape, resulting in difficulty in focusing on nearby objects (less accommodation). This is a normal age-related change and is known as presbyopia.

Question 6

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 following is the most likely explanation for why this works?

Accepted Answer

Reducing the inertia of head spin by using the technique of "spotting" limits the movement of the head. This, in turn, reduces the flow of endolymph within the semicircular canals of the inner ear, which would otherwise deflect the hair cells of the crista ampullaris. The deflection of these hair cells is a key part of how the body senses rotation. By minimizing this deflection, dancers can reduce the sensation of dizziness that typically accompanies spinning.

Question 7

Paralysis of which eye muscle would prevent the right eye from looking to the left?

Accepted Answer

The medial rectus muscle of the right eye is responsible for moving the eye inward, towards the nose, which is necessary for looking to the left. If the medial rectus is paralyzed, the right eye would not be able to move in this direction.

Question 8

The quality of a sound is based on the atmospheric pressure at the time the sound is generated.

Accepted Answer

The quality of a sound is determined by factors such as frequency, amplitude, harmonics, and timbre. The atmospheric pressure may affect the transmission of sound, but it does not determine the quality of the sound itself.

Question 9

Labyrinthitis is a medical condition often caused by a 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?

Accepted Answer

Labyrinthitis commonly causes loss of balance and dizziness due to swelling and inflammation in the inner ear, which controls balance and spatial orientation. Other symptoms may include nausea, vomiting, and ringing in the ears. However, auditory hallucinations and loss of hearing are less commonly associated with this condition.

Question 10

Select the statement below that is NOT true with regards to the process of light adaptation.

Accepted Answer

The process of light adaptation involves a decrease in retinal sensitivity due to rhodopsin being uncoupled from light transduction, resulting in a reduction in the activity of rods. However, visual acuity actually improves during light adaptation because the increased activity in cones in bright light allows for better discrimination of fine details. Therefore, statement B is not true.

Question 11

If you shine a light into one eye both pupils will constrict. The best explanation for this is .

Accepted Answer

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. Therefore, shining a light into one eye can stimulate both pupils to constrict.

Question 12

A patient has a loss of hearing in only one ear. Which of the following is likely to be a result?

Accepted Answer

Localization of sound requires binaural hearing, or the ability to compare differences in sound between both ears. With hearing loss in only one ear, the patient will not be able to accurately determine the origin of sounds.

Question 13

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?

Accepted Answer

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.

Question 14

The sensation of loudness or the volume of a sound is detected by _.

Accepted Answer

The greater movement of the basilar membrane results in greater deflection of the hair cells, which then send signals to the brain indicating a louder volume of sound. Option A is incorrect because faster vibration of the basilar membrane indicates a higher frequency of sound, not necessarily a louder volume. Option B is incorrect because simply stimulating a greater number of hair cells does not necessarily indicate a louder volume of sound. Option D is incorrect because the sound energy traveling all the way to the apex of the scala vestibule with enough energy remaining to deflect hair cells is a characteristic of high amplitude sounds, not necessarily loudness.

Question 15

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?

Accepted Answer

Color perception is achieved by activation of various combinations between the three cone types. By varying the relative stimulation of the cones, our brain can differentiate between many thousands of colors. This is called trichromatic color vision. The rods also contribute to our perception of brightness and play a role in our ability to see in dim lighting conditions.

Question 16

Which of the following is the best explanation for our perception of color?

Accepted Answer

Cones come in three types, each sensitive to different wavelengths of light.

Question 17

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 cells are maintained?

Accepted Answer

The aqueous humor is continuously replenished and flows from the ciliary process to drain in the scleral venous sinus to provide nutrients and remove waste products from the avascular cells of the cornea and lens in the anterior segment of the eye.

Question 18

As light travels through the eye, it passes through several structures or chambers before reaching the retina. Which list below gives those structures in the correct order?

Accepted Answer

The correct order in which light travels through the eye is: cornea, anterior chamber (the space between the cornea and the iris), pupil (the opening in the iris), lens, and finally the posterior segment (which includes the vitreous humor and leads to the retina). This sequence ensures that light is properly focused onto the retina for clear vision.

Question 19

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?

Accepted Answer

B) explains the higher resolution of color vision by detailing the more direct neural pathway of cones compared to rods, which allows for finer detail to be resolved.

Question 20

Which of the following is the best explanation of why it is difficult to discriminate the color of an object at night?

Accepted Answer

At night, the dilation of pupils allows more light to enter the eye, stimulating the retina where there are more rods than cones. Rods are not as effective as cones in discriminating colors, making it difficult to differentiate colors at night.

Quiz 15: The Special Senses