Chapter 15 | The Special Senses

Clinical Questions: 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 they, how do they occur, and how are they treated?

A cataract is a clouding of the lens that causes the world to appear distorted, as if looking through frosted glass. Some cataracts are congenital, but most are due to age-related hardening and thickening of the lens, or are a possible consequence of diabetes mellitus. The direct cause is probably inadequate delivery of nutrients to the deeper lens fibers. The metabolic changes that result are thought to promote unfolding of the lens proteins. Unprotected exposure to the UV rays of sunlight over time is also associated with cataract formation. The lens can be removed and replaced with an artificial lens.

Tinnitus, vertigo, and gradual hearing loss typify the disorder called ________. A) Ménière's syndrome B) conjunctivitis C) strabismus D) motion sickness

A) Ménière's syndrome

Select the correct statement about olfaction. A) Olfactory receptors have a high degree of specificity toward a single type of chemical. B) Some of the sensation of olfaction is actually one of pain. C) Substances must be volatile and hydrophobic in order to activate olfactory receptors. D) Olfactory adaptation is only due to fading of receptor cell response.

A) Olfactory receptors have a high degree of specificity toward a single type of chemical.

Which of the following types of receptors are located in the mouth? A) chemoreceptors, mechanoreceptors, thermoreceptors, and nociceptors B) chemoreceptors only C) chemoreceptors, thermoreceptors, and nociceptors only D) thermoreceptors, mechanoreceptors, and nociceptors only

A) chemoreceptors, mechanoreceptors, thermoreceptors, and nociceptors

Receptors for hearing are located in the ________. A) cochlea B) semicircular canals C) tympanic membrane D) vestibule

A) cochlea

Which of the following best describes the function of the iris? A) controls amount of light entering eye B) gives the eye its color C) refracts light through the pupil D) adjusts the shape of the lens

A) controls amount of light entering eye

Seventy percent of all sensory receptors are located in the ________. A) eye B) ears C) skin D) nose

A) eye

26) Which of the following types of neurons are replaced throughout adult life? A) olfactory receptor cells B) retinal bipolar cells C) retinal ganglion cells D) auditory outer and inner hair cells

A) olfactory receptor cells

Which of the following describes a response of the eye to sympathetic stimulation? A) pupil dilation B) pupil constriction C) ciliary muscle contraction D) ciliary muscle relaxation

A) pupil dilation

If you shine a light into one eye both pupils will constrict. The best explanation for this is ________. A) 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 B) a small portion of light always enters the other eye C) information from one eye is directly and immediately transferred to the other eye to maintain alignment of the eyes D) This, in fact, does not occur; information from both eyes is always separated.

A) 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

Match the following: A) Lens B) Aqueous humor C) Fovea centralis D) Retina 1) The sensory layer of the eye. 2) The structure most responsible for focusing light rays that enter the eye. 3) Helps maintain the intraocular pressure; located in the anterior part of the eye. 4) Area of greatest visual acuity.

A2 B3 C4 D1

Match the following: A) Vestibule B) Tympanic membrane C) Pharyngotympanic tube D) Otoliths 5) Ear stones. 6) Connects the middle ear with the nasopharynx. 7) Separates external acoustic meatus from the middle ear. 8) Contains utricle and saccule. 9) Detects linear acceleration.

A9 B7 C6 D5 D8

A patient who has experienced previous jaw and face trauma now reports difficulty tasting with the tip of her tongue. Which cranial nerve was likely damaged in that injury? A) Glossopharyngeal (IX) B) Facial (VII) C) Hypoglossal (XII) D) Trigeminal (V)

B) Facial (VII)

Taste buds are NOT found ________. A) in fungiform papillae B) in filiform papillae C) in circumvallate papillae D) lining the buccal cavity

B) in filiform papillae

The elasticity of the lens decreases with age. This leads to which of the following? A) a clouding of the lenses known as a cataract B) less accommodation of the lenses and difficulty focusing on nearby objects C) less light getting to the retina and diminished visual acuity D) lowered accommodation of the pupillary reflex and blurry vision

B) less accommodation of the lenses and difficulty focusing on nearby objects

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? A) auditory hallucination B) loss of balance and dizziness C) loss of hearing D) ringing in the ears (tinnitus)

B) loss of balance and dizziness

Ceruminous glands are ________. A) saliva glands found at the base of the tongue B) modified apocrine sweat glands C) glands found in the lateral corners of your eye D) modified taste buds

B) modified apocrine sweat glands

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? A) Taste receptors that are active at the same time influence the subtlety of what we smell. B) The olfactory pathway travels to location in the brain in which memories are formed and we simply mix this new sensory information with old memories. C) 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. D) The belief that we can smell so many different distinct odors is a psychological process referred to as an uncinate fit or olfactory hallucination.

C) 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.

Damage to the medial rectus muscles would probably affect ________. A) refraction B) accommodation C) convergence D) pupil constriction

C) convergence

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 ________. A) is not a living tissue B) has no nerve supply C) has no blood supply D) does not contain connective tissue

C) has no blood supply

The eye muscle that rotates the eye upward and turns the eye laterally is the ________. A) lateral rectus B) superior oblique C) inferior oblique D) medial rectus

C) inferior oblique

The only special sense NOT fully functional at birth is the sense of ________. A) smell B) taste C) vision D) hearing E) equilibrium

C) vision

What is the main function of the rods in the eye? A) depth perception B) color vision C) vision in dim light D) accommodation for near vision

C) vision in dim light

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? A) When the eyes send a static vision of stability to the brain, it is tricked into believing the body is still and therefore dizziness will not occur. B) This helps keep the motions detected by the eyes congruent (aligned) with the motions sensed by the vestibular apparatus. C) This will help to reduce the lateral flection of the head and will prevent hyper polarization or depolarization of the hair cells in the macula. D) Reducing the inertia of head spin will reduce the flow of endolymph that deflects the hair cells of the crista ampullaris.

D) Reducing the inertia of head spin will reduce the flow of endolymph that deflects the hair cells of the crista ampullaris.

The blind spot of the eye is caused by ________. A) more rods than cones within the retina B) the macula lutea interrupts the nerve pathway C) an absence of cones in the foveae D) an absence of photoreceptors where the optic nerve leaves the eye

D) an absence of photoreceptors where the optic nerve leaves the eye

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? A) cornea, lens, pupil, anterior chamber, posterior segment B) cornea, pupil, anterior chamber, lens, posterior segment C) cornea, pupil, lens, anterior chamber, posterior segment D) cornea, anterior chamber, pupil, lens, posterior segment

D) cornea, anterior chamber, pupil, lens, posterior segment

Nerve fibers from the medial aspect of each eye ________. A) go to the superior colliculus only B) pass posteriorly without crossing over at the chiasma C) divide at the chiasma, with some crossing and some not crossing D) cross over to the opposite side at the chiasma

D) cross over to the opposite side at the chiasma

What structure regulates the amount of light passing to the visual receptors of the eye? A) aqueous humor B) lens C) cornea D) iris

D) iris

Which of the following structures is NOT part of the external ear? A) pinna B) external acoustic meatus C) tympanic membrane D) pharyngotympanic tube

D) pharyngotympanic tube

T/F: Sound is generally perceived in the occipital lobe of the cerebral cortex.

False

T/F: The anterior chamber of the eye is filled with vitreous humor.

False

T/F: The structure that allows equalization of the pressure in the middle ear with the atmospheric pressure is the external auditory meatus.

False

Short Answer: The middle ossicle in the ear is the___

Incus

Paralysis of which eye muscle would prevent the right eye from looking to the left? A) Lateral rectus B) Superior rectus C) Medial rectus D) Inferior rectus

Medial rectus

Short Answer: Hot chili peppers contain a chemical compound called capsaicin that stimulates which type of receptor?

Nociceptors

Short Answer: Explain why prolonged periods of reading tire the eye muscles and result in eye strain.

Prolonged periods of reading tend to tire the eye muscles and result in eye strain because of the continuous use of pupillary constriction and convergence. As one is reading, they tend to blink less as well, and blinking nourishes your eye with oxygen and nutrients. This keeps your eyes healthy and comfortable

Short Answer: Taste is solely a response to chemicals dissolved in the___

Saliva

Clinical Questions: A 60-year-old woman is experiencing vertigo. She ignores the symptoms initially, but now her attacks are accompanied by severe nausea and vomiting. Following an attack, she hears a roaring in her ears that causes temporary deafness for some time after. What do you think her problem is, and what is its suspected cause?

She most likely has a condition known as Ménière's syndrome. It affects both the semicircular canals and the cochlea. The cause of the syndrome is uncertain, but it may result from distortion of the membranous labyrinth by excessive endolymph accumulation. Less severe cases can usually be managed by antimotion drugs. For more debilitating attacks, salt restriction and diuretics are used to decrease overall extracellular fluid volumes.

Short Answer: Trace the pathway of sound as it enters the external ear until it is perceived in the brain.

Sound first enters through the external acoustic meatus which causes vibration of the eardrum. Those vibrations are then delivered by the auditory ossicles through the oval window. This creates fluid pressure waves in the cochlea which stimulates the hair cells of the spinal organ. Then the impulses are sent by the cochlear nerve to the temporal lobe of the brain. Then the auditory cortex perceives the information as sound.

Clinical Questions: Baby Susie's pediatrician notices that one of her eyes rotates outward and that she does not appear to be using it for vision. What is her condition and what does the pediatrician recommend?

Susie has strabismus, caused by congenital weakness of the external eye muscles in her affected eye. To prevent this eye from becoming functionally blind, the doctor will recommend either eye exercises or putting a patch on the unaffected eye to force her to use the affected eye. If her case is deemed severe, surgery on the eye muscles will be recommended.

Short Answer: What is the pharyngotympanic tube and what is its purpose?

The pharyngotympanic tube is what connects your middle ear to the lateral wall of the nasopharynx. Its purpose is to ventilate the ear systems, clearing mucus from within the middle ear into the nasopharynx. It tends to close and flatten, but simply yawning or swallowing can open it briefly, equalizing air pressure.

Short Answer: Explain why a bad cold can result in food not tasting the same as it normally does.

This is because taste is correlated greatly with smell. Therefore, if someone has a bad cold, their ability to smell is blocked by nasal congestion. Because they can't smell as well, they won't be able to taste as well either.

Short Answer: When you go to the fair and ride the roller coaster, where do those wild sensations come from?

Those wild sensations we feel comes from when the crista ampullaris becomes excited by excessive movement in our semicircular canals. The wild sensations are a result of our eyes telling us one thing while our semicircular canals are telling us another thing. Symptoms that can occur include dizziness and sickness.

T/F: The function of the lens of the eye is to allow precise focusing of light on the retina.

True

T/F: The mucous membrane that lines the eyelids and is reflected over the anterior surface of the eyeball is the conjunctiva.

True

T/F: The optic disc forms a blind spot where the optic nerve leaves the eyeball.

True

Short Answer: Explain why your nose runs during and immediately after a good cry.

Your nose tends to run during and immediately after a good cry because your tears go into the lacrimal canaliculi. It goes from there into the nasolacrimal sac. As a result of the sac filling up, the tears will run down the nasolacrimal duct of your nose.