15. Special Senses

The accessory structures of the eye do NOT include the __________.

The __________ dilate the pupils of the eyes.

Choose the true statement about the cornea.

The conjunctival mucous membrane covers __________.

Arrange the tunics of the wall of the eyeball in their correct sequence from deep to superficial.

The __________ is NOT a part of the vascular layer of the eye.

Internal structures of the eye

Identify the structures in the following horizontal section of the eye. a. ___ b. ___ c. ___ d. ___ e. ___ f. ___ g. ___ h. ___ i. ___ j. ___

A blind spot occurs in the retina where (a) the fovea centralis is located, (b) ganglion cells synapse with bipolar cells, (c) the optic nerve attaches to the retina, (d) rod cells are clustered to form the macula, (e) amacrine cells are located.

Multiple Choice More than one choice may apply. Which cranial nerve controls contraction of the circular smooth muscle of the iris? a. Trigeminal b. Facial c. Oculomotor d. Abducens

Multiple Choice More than one choice may apply. The cornea is nourished by a. corneal blood vessels. b. aqueous humor. c. vitreous humor. d. scleral blood vessels.

Multiple Choice More than one choice may apply. When the eye focuses for far vision, a. the lens is at its thinnest. b. the ciliary muscles contract. c. the light rays are nearly parallel. d. suspensory fibers of the ciliary zonule are slack.

The retina is also called (a) the vascular layer, (b) the fibrous layer, (c) the inner layer, (d) all of these.

Multiple Choice More than one choice may apply. Convergence a. requires contraction of the medial rectus muscles of both eyes. b. is needed for near vision. c. involves transmission of impulses along the abducens nerves. d. can promote eyestrain

At sunset, your visual system adapts to (a) fovea vision, (b) rod-based vision, (c) macular vision, (d) cone-based vision.

A better-than-average visual acuity rating is (a) 20/20, (b) 20/30, (c) 15/20, (d) 20/15.

The phenomenon of dark adaptation is best explained by the fact that a. rhodopsin does not function in dim light, b. rhodopsin breakdown occurs slowly, c. rods exposed to intense light need time to generate rhodopsin, d. cones are stimulated to function by bright light.

Nearsightedness is more properly called a. myopia, b. hyperopia, c. presbyopia, d. emmetropia.

Multiple Choice More than one choice may apply. Match the letter of the appropriate structure on the figure to its description. Attachment of the optic nerve at this site results in a blind spot

Multiple Choice More than one choice may apply. Match the letter of the appropriate structure on the figure to its description. Gel-like fluid filling the posterior eye chamber

Multiple Choice More than one choice may apply. Match the letter of the appropriate structure on the figure to its description. Smooth muscle that contracts to cause lens accommodation

Multiple Choice More than one choice may apply. Match the letter of the appropriate structure on the figure to its description. Pigmented, vascular tunic deep to the fibrous tunic

Which reactions occur when a person looks at a distant object? a. pupils constrict, ciliary zonule (suspensory ligament) relaxes, lenses become less convex; b. pupils dilate, ciliary zonule becomes taut, lenses become less convex; c. pupils dilate, ciliary zonule becomes taut, lenses become more convex; d. pupils constrict, ciliary zonule relaxes, lenses become more convex.

The blind spot of the eye is a. where more rods than cones are found, b. where the macula lutea is located, c. where only cones occur, d. where the optic nerve leaves the eye.

Compare and contrast emmetropia, hyperopia, and myopia. What type of lenses will help correct each of these?

Trace the pathway of light from the time it hits the cornea until it excites the rods and cones.

(a) What structures make up the fibrous layer of the eye?

(b) What are the functions of the fibrous layer?

What structures make up the vascular layer of the eye?

Nine children attending the same day-care center developed red, inflamed eyes and eyelids. What are the most likely cause and name of this condition?

What is the usual result if a sebaceous gland of an eyelash or a tarsal gland becomes infected?

Damage to the medial recti muscles would probably affect a. accommodation, b. refraction, c. convergence, d. pupil constriction.

Blockage of the scleral venous sinus might result in a. a sty, b. glaucoma, c. conjunctivitis, d. a cataract.

Explain the role of vitamin A in vision.

When viewing an object close to you, your lens should be more_______. (a) rounded, (b) flattened, (c) concave, (d) lateral, (e) medial.

You are at a park watching some deer 35 feet away from you. A friend taps you on the shoulder to ask a question. As you turn to look at your friend, who is standing just 2 feet away, what changes would your eyes undergo?

Your friend Shelly suffers from myopia (nearsightedness). You remember from your physics class that concave lenses cause light waves to spread or diverge and that convex lenses cause light waves to converge. What type of corrective lenses would you suggest to your friend? (a) concave lenses, (b) convex lenses.

Of the neurons in the retina, the axons of which of these form the optic nerve? a. bipolar cells, b. ganglion cells, c. cone cells, d. horizontal cells.

The vast majority of refractive problems in the eye are related to the __________.

When focusing on a distant object, the lens is __________.

Which sequence best describes a normal route for the flow of tears from the eyes into the nasal cavity? a. lacrimal canaliculi, lacrimal sacs, nasolacrimal ducts; lb. acrimal ducts, lacrimal canaliculi, nasolacrimal ducts; c. nasolacrimal ducts, lacrimal canaliculi, lacrimal sacs.

The portion of the fibrous layer that is white and opaque is the a. choroid, b. cornea, c. retina, d. sclera.

Accessory glands that produce an oily secretion are the a. conjunctiva, b. lacrimal glands, c. tarsal glands.

Since there are only three types of cones, how can you explain the fact that we see many more colors?

Describe the response of rhodopsin to light stimuli. What is the outcome of this cascade of events?

Which sequence follows the correct passage of light entering the cornea?

Which of the following shows the correct order of light transmission from the air to the retina?

The optic disc on the retina is __________.

How do rods and cones differ functionally?