Lab Quiz 5

How many extrinsic eye muscles are attached to the exterior surface of each eyeball?

6

Humans, cats, predatory birds, and most primates are endowed with ____________. Their visual fields, each about 170 degrees, overlap to a considerable extent; thus there is two-eyed vision at the overlap area.

Binocular vision

Superior oblique. Name the action and controlling cranial nerve.

Depresses eye and turns it laterally, IV (trochlear)

Inferior rectus. Name the action and controlling cranial nerve.

Depresses eye and turns it medially, III (oculomotor)

Inferior oblique. Name the action and controlling cranial nerve.

Elevates eye and turns it laterally, III (oculomotor)

Superior rectus. Name the action and controlling cranial nerve.

Elevates eye and turns it medially, III (oculomotor)

True or False. Texture, temperature, and smell have little or no effect on the sensation of taste.

False

The outermost __________ is a protective layer composed of dense avascular connective tissue.

Fibrous layer

True or False. At the optic chiasma, the fibers from the medial side of each eye cross over to the opposite side.

True

True or False. Receptors for olfaction and taste are classified as chemoreceptors because they respond to chemicalsin solution.

True

________, or sharpness of vision, is generally tested with a Snellen eye chart, which consists of letters of various sizes printed on a white card.

Visual acuity

Photoreceptors stimulate _________ neurons, which in turn stimulate ganglion cells.

bipolar

The retina consists of two main types of cells: a pigmented _________, which abuts the choroid, and an inner cell layer composed of _________, which is in contact with the vitreous humor.

epithelium and neurons

Projecting from the border of each eyelid is a row of short hairs, the __________.

eyelashes

In the center of the macula lutea is the __________, a minute pit about 0.4 mm in diameter, which contains mostly cones and is the area of greatest visual acuity. This is where the focusing for discriminative vision occurs.

fovea centralis

Farsightedness. Such persons have no problems with distant vision but need glasses with convex lenses to augment the converging power of the lens for close vision.

hyperopia

The _________ is composed of circularly and radially arranged smooth muscle fibers and acts as a reflexively activated diaphragm to regulate the amount of light entering the eye.

iris

The most anterior part of the uvea is the pigmented _________, which is incomplete, resulting in a rounded opening, the _________, through which light passes.

iris and pupil

Light entering the eye is focused on the retina by the ________, a flexible crystalline structure held vertically in the eye's interior by the __________, more specifically called the ciliary zonule, attached to the ciliary body.

lens and suspensory ligament

The lacrimal secretion contains __________, an anti bacterial enzyme which cleanses and protects the eye surface as it moistens and lubricates it.

lysozyme

Lateral to each blind spot, and directly posterior to the lens, is an area called the ___________, an area of high cone density, "yellow spot".

macula lutea

Individuals in whom the image normally focuses in front of the retina are said to have ________, or nearsightedness; they can see close objects without difficulty, but distant objects are blurred or seen indistinctly.

myopia

The organ of smell is the _________, located in the roof of the nasal cavity.

olfactory epithelium

Photoreceptor cells are distributed over the entire neural retina, except where the optic nerve leaves the eyeball. This site is called the macula lutea/optic disc.

optic disc

Most taste buds are located in ___________, peg like projections of the tongue mucosa.

papillae

The outer _____________ abuts the choroid and extends anteriorly to cover the ciliary body and the posterior side of the iris.

pigmented epithelium

The innermost sensory layer of the sensory layer of the eye is the delicate, two-layered _________.

retina

________ are specialized receptors for dim light. Visual interpretation of their activity is in gray tones.

rods

The transparent inner neural layer extends anteriorly only the the ciliary body. It contains the photoreceptors, ________ and _________, which begin the chain of electrical events that ultimately result in the transduction of light energy into nerve impulses that are transmitted to the optic cortex of the brain.

rods and cones

In order to taste something, it has to be in ___________.

solution

The site where photoreceptor cells are NOT distributed, or blind spot is called the ________.

optic disc

The __________, specific receptors for the sense of taste, are widely but not uniformly distributed in the oral cavity.

taste buds

Most taste buds are mad of two/three types of modified epithelial cells.

two

The middle layer, called the _________, is the vascular layer.

uvea

The ___________ provides the major internal reinforcement of the posterior part of the eyeball, and helps to keep the retina pressed firmly against the wall of the eyeball. It is formed only before birth

vitreous humor

Ishihara's color plates are designed to test for deficiencies in the cones or color photorecetor cells called_________.

Color blindness

This specialized surface reflects the light within the eye and is found in the eyes of animals that live under conditions of low-intensity light. It is not found in humans.

Tapetum lucidum

The ability of the eye to focus differentially for objects of near vision (less that 6m, or 20 feet) is called _______.

accommodation

The ability of the eye to focus differentially for objects of near vision is called _______.

accommodation

You will use absorbent cotton and oil of wintergreen, peppermint, or cloves to test for olfactory.

adaptation

The aqueous humor/vitreous humor is a clear, watery fluid that helps maintain the intraocular pressure of the eye and provides nutrients for the avascular lens and cornea.

aqueous humor

Irregularities in the curvatures of the lens and/or the cornea lead to a blurred vision problem called __________.

astigmatism

Olfactory receptor cells are bipolar/unipolar neurons whose olfactory cilia extend outward from the epithelium.

bipolar

The posterior most part of the uvea is the __________, is a blood-rich nutritive region containing a dark pigment that prevents light scattering within the eye.

choroid

The aqueous humor is continually formed by the capillaries of the _________ of the ciliary body.

ciliary processes

Photoreceptors of the eye include rods and cones. Which one is responsible for interpreting color, but can function only under conditions of high light intensity?

cones

________ are color receptors that permit high levels of visual acuity, but they function only under conditions of high light intensity.

cones

Inflammation of the conjunctiva, often accompanied by redness of the eye, is called ________.

conjunctivitis

___________, or medial eye movements, which is essential for near vision. When this occurs, both eyes are directed toward the near object viewed. The extrinsic eye muscles are controlled by the somatic nervous system.

convergence

The wall of the eye has 3 layers. The outermost fibrous layer is composed of the opaque, white sclera and the transparent ___________.

cornea

Lateral rectus. Name the action and controlling cranial nerve.

Moves eye laterally, VI (abducens)

Medial rectus. Name the action and controlling cranial nerve.

Moves eye medially, III (oculomotor)

The fibrous layer contains two regions. The opaque white ________ knows as the "white of the eye" and the transparent _________, through which light enters the eye.

Sclera and Cornea

There are five basic taste sensations. Name one.

Sweet

___________ helps to maintain the intraocular pressure of the eye and provides nutrients for the avascular lens and cornea.

aqueous humor

The lens divides the eye into two segments: the anterior segment which contains a clear watery fluid called the ________, and the posterior segment, filled with a gel-like substance, the __________.

aqueous humor and vitreous humor

The choroid is modified to form the _________, which is chiefly composed of ciliary muscles, important in controlling lens shape, and ciliary processes, which secrete aqueous humor.

ciliary body

Name the mucous membrane that lines the internal surface of the eyelids and continues over the anterior surface of the eyeball.

conjunctiva

The afferent fibers from the taste buds to the sensory cortex in the postcentral gyrus of the brain are carried in three cranial nerves: the __________ serves the anterior two-thirds of the tongue; the _________ serves the posterior third of the tongue; and the _________ carries a few fibers from the pharyngeal region.

facial nerve (VII), glossopharyngeal nerve (IX), vagus nerve (X)

The anterior surface of each eye is protected by eyelids or __________.

palpebrae

The long microvilli of the receptor cells penetrate the epithelial surface through an opening called the ________.

taste pore