Lab Quiz Material: Exercise 23 & 24

LABEL DIAGRAM CORRECTLY; KNOW

(circled)

Smooth muscle structures (2)

1) iris 2) ciliary body

In the experiment on the photo pupillary reflex, what happened to the pupil of the eye exposed to light?

Constricted

What does the retina look like?

Thin yellow-white/tan membrane (often becomes crumpled during dissection of the eye)

The eyeball is wrapped in adipose tissue within the orbit. What is the function of the adipose tissue?

To package, protect, and cushion the eyeball in the bony orbit

Ability to focus for close (less than 20 feet) vision

accommodation

Fluid filling the anterior segment of the eye

aqueous humor

Blurred vision due to unequal curvatures of the lens of cornea

astigmatism

Forms the bulk of the heavily pigmented vascular layer

choroid

During close vision, the ciliary muscle is ___

contracted

Medial movement of the eyes during focusing on close objects

convergence

Anterior continuation of the sclera--your "window on the world"

cornea

Light refraction is ___

decreased

The convexity of the lens is ___

decreased

What is the advantage of binocular vision?

depth perception

Normal vision

emmetropia

Area of critical focusing and discriminatory vision

fovea centralis

The axons of the ___ cells form the optic nerve, which exits from the eyeball

ganglion

The iris is composed primarily of two smooth muscle layers, one arranged radially and the other circularly. Which of these dilates the pupil?

the radial layer

Substance occupying the posterior segment of the eyeball

vitreous humor

(1) are the photoreceptors that operate best in bright light and allow for color vision.

(1) Cones

In farsightedness, the light is focused (1) the retina. The lens required to treat myopia is a (2) lens. The "near point" increases with age because the (3) of the lens decreases as we get older. A convex lens, like that of the eye, produces an image that is upside down and reversed from left to right. Such an image is called a (4) image.

(1) behind (2) concave (3) flexibility (4) real

Only (1) are found in the fovea centralism, whereas mostly (2) are found in the periphery of the retina.

(1) cones (2) rods

WHY DOES ONE USUALLY NEED TO BLOW ONE'S NOSE AFTER CRYING?

--> Because tears drain/flow to the nasal cavity via the nasolacrimal ducts.

WHAT COLORS OF LIGHT DO THE CONES RESPOND TO?

--> blue, green, & red

DEFINE ASTIGMATISM.

--> blurred vision due to unequal curvatures of the lens or cornea

WHAT IS THE TAPETUM LUCIDUM AND WHAT IS ITS FUNCTION?

--> it is the membrane that animals have that allows them to see in the dark & reflects light

WHAT IS THE BLIND SPOT AND WHY DOES ITS NAME FIT IT PROPERLY?

--> the optic disc is the blind spot because it doesn't have photoreceptors, therefore, it does not allow vision to occur here

You would expect the pupil to be dilated in which of the following circumstances?

1) In dim light 2) observing distant objects

NAME THREE ACCESSORY STRUCTURES THAT CONTRIBUTE TO FORMATION OF TEARS AND/OR LUBRICATE THE EYEBALL AND THE MAJOR SECRETORY PRODUCT FOR EACH.

1) Lacrimal apparatus (gland) --> dilute salt solution (tears); has lysosomes which fights off bacteria (antibacterial enzyme) 2) conjunctiva --> mucous that aids in lubrication 3) tarsal glands --> secretes an oily substance

Light-bending media of the eye (4)

1) aqueous humor 2) cornea 3) lens 4) vitreous humor

The visual pathway to the occipital lobe of the brain consists most simply of a chain of five cells. Beginning with the photoreceptors cell of the retina, name them and note their location in the pathway.

1) photoreceptor cell; retina 2) bipolar cell; retina 3) ganglion cell; retina 4) neuron; lateral geniculate nucleus of the thalamus 5) cortical neuron; visual cortex of the cerebral hemispheres

Why is the ophthalmoscopic examination an important diagnostic tool

Allows noninvasive examination of the retinal condition and vasculature

Explain why vision is lost when light hits the blind spot

Area lacks photoreceptors

At what point is it attached to the posterior aspect of the wall?

At the optic disc

Explain the difference between binocular and panoramic vision

Binocular: visual fields overlap considerably but not completely --> slightly difference views received by each eye Panoramic: little to no overlap of visual fields --> each eye "sees" different view

How can astigmatism be corrected?

Glasses, contacts, cured --> laser eye surgery

What is a sty?

Inflammation of a sweat gland associated with eye exterior

Conjunctivitis

Inflammation of the conjunctiva of white parts of the eye specifically

What happened to the pupil of the non illuminated eye? & Explanation

Regulation of pupil. Constriction, by parasympathetic division of autonomic nervous system is coordinated and prevents over illumination of the delicate retinal cells

What factors(s) are responsible for binocular vision?

Slight different between visual fields of the two eyes and parietal crossover at optic nerve

What modification of the choroid that is not present in humans is found in the cow eye?

Tapetum

What is the Tapetum's function?

To reflect light that enters the eye, thus increasing light stimulation of the retina under dim light

How can you explain the fact that we see a great range go colors even though only three cone types exist?

When more than one cone type is stimulated simultaneously immediate colors are seen

LABEL DIAGRAM CORRECTLY.

aqueous humor () cornea (a) sclera (h) choroid (f) fovea centrales (q) optic disc (r) optic nerve (l) anterior chamber (c) photoreceptors (u) anterior segment (m) dura mater (k) posterior chamber (g) bipolar cells (t) posterior segment (o) ganglion cells (s) retina (j) ciliary body and processes (i) iris (p) ciliary muscle (e) scleral venous sinus (d) ciliary muscle (e) ciliary zonule (suspensory ligament) (n)

Modification of the choroid that controls the shape of the crystalline lens and contains the ciliary muscle

ciliary body

Form (by filtration) the aqueous humor

ciliary processes of ciliary body

Inability to focus well on close objects (farsightedness)

hyperopia

Lens convexity is ___

increased

Nearsightedness

myopia

Part of the retina that lacks photoreceptors

optic disc

The two major layers of the retina are the pigmented and neural layers. In the neural layer, the neuron populations are arranged as follows from the pigmented layer to the vitreous humor.

photoreceptors, bipolar cells, ganglion cells

Light bending

refraction

During distance vision, the ciliary muscle is ___

relaxed

The ciliary zonule is

relaxed

Layer containing the rods and cones

retina

The dim light receptors are the ___.

rods

Composed of tough, white, opaque, fibrous connective tissue

sclera

The "white" of the eye

sclera

Drains aqueous humor from the eye

scleral venous sinus

The ciliary zonule is ___

taut