Chapter 15

Night blindness Conduction deafness Otitis media Glaucoma

-A condition that can result from a deficiency of vitamin A. -A condition of deafness that may result from otosclerosis. -An inflammation of the lining of the middle ear. -A condition often leading to blindness due to increased intraocular pressure.

Which of the following is not a possible cause of conduction deafness?

-Cochlear nerve degeneration.

Vision is fully developed at birth.

-False.

Sensorineural deafness Conduction deafness Tinnitus Conduction deafness Conduction deafness

-Loss of hearing resulting from prolonged exposure to high-intensity sounds. -Can result from the fusion of the auditory ossicles. -A possible side effect of medications such as aspirin. -One of the most common results of otitis media. -Can result from impacted cerumen.

Tinnitus, vertigo, and gradual hearing loss typify the disorder called ________.

-Ménière's syndrome.

Motion sickness seems to ________.

-Result from mismatch between visual and vestibular inputs.

Retina Lens Aqueous humor Fovea centralis

-The sensory layer of the eye. -The structure most responsible for focusing light rays that enter the eye. -Helps maintain the intraocular pressure; located in the anterior part of the eye. -Area of greatest visual activity.

The only special sense not fully functional at birth is the sense of ________.

-Vision.

Ling, a 75-year-old grandmother, complained that her vision was becoming obscured. Upon examination by an ophthalmologist she was told she had cataracts. What are cataracts, how do they occur, and how are they treated?

A cataract is a clouding of the lens. Some cataracts are congenital, but most are due to age-related hardening and thickening of the lens, diabetes mellitus, or exposure to UV rays over time. The lens can be removed and replaced with an artificial lens.

What term means that the lens can change shape so that the eye can focus on items either close at hand or far away?

Accommodation.

Bitter taste is elicited by ________.

Alkaloids.

Receptors for hearing are located in the ________.

Cochlea.

Damage to the medial rectus muscles would probably affect ________.

Convergence.

Light passes through the following structures in which order?

Cornea, aqueous humor, lens, vitreous humor.

Seventy percent of all sensory receptors are located in the ________.

Eye.

Taste is independent of smell.

False.

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.

Dark adaptation ________.

Involves accumulation of rhodopsin.

The visible colored portion of the eye is the __________.

Iris.

What condition results when distant objects focus in front of the retina, rather than on it?

Myopia.

Most taste buds are located __________.

On the tongue.

What part of the eye constitutes the blind spot?

Optic disc.

The major function of the conjunctiva is to __________.

Produce mucus to prevent the eyes from drying out.

Which photoreceptors respond to very dim light?

Rods.

Olfactory cells and taste buds are normally stimulated by ________.

Substances in solution.

Roger went for his yearly eye examination and was informed that his intraocular pressure was slightly elevated (at 22 mm Hg). The physician expressed concern over this condition and noted that if the condition got worse, eyedrops would be merited. What is wrong with Roger's eyes? What are the possible consequences of this condition? What is the function of the eyedrops?

The condition is glaucoma. Blindness could result if not treated or caught early. The eyedrops increase the rate of aqueous humor drainage or decrease its production.

Which of the following is a characteristic of the lens?

The lens focuses light on the retina.

The blind spot of the eye is where ________.

The optic nerve leaves the eye.

Which of the following is NOT a requirement for something to be tasted?

The tastant must contact the basal epithelial cells of the taste buds.

Ringing in the ears is called __________.

Tinitus.

Odorants must be volatile to be smelled.

True.

The function of the lens of the eye is to allow precise focusing of light on the retina.

True.

The optic disc is the location where the optic nerve leaves the eyeball.

True.

The photoreceptor cells are sensitive to damage from light.

True.

When we move from darkness to bright light, retinal sensitivity is lost, but visual acuity is gained.

True.

The boundary between the external and middle ear is the __________.

Tympanic membrane.

Which of the following taste sensations is incorrectly matched to the chemicals that produce it?

Umami-triglycerides and fatty acids

What is the main function of the rods in the eye?

Vision in dim light.