BIO 321 Chpter 7.4

Müller

Approximately 20% of the volume of the retina is taken up by glial cells which provide metabolic support for retinal neurons and mediate neurotransmitter degradation. These are called ______ cells. Multiple choice question. Müller Rummenigge Breitner Foster Maier

relaxes; flattens

As the distance between the eye and a viewed object increases, the object is kept in focus because the ciliary muscle Blank______ and the lens Blank______. Multiple choice question. contracts; flattens relaxes; flattens relaxes; rounds contracts; rounds

Cornea Lens

Astigmatism results from an irregularity in the curvature of which of the following? Multiple select question. Retina Cornea Lens Pupil Iris

bleaching

During light adaptation, rhodopsin becomes inactivated, a process sometimes called what?

Put the layers of the retina in the order that light passes through them. Start with the first layer on top.

Ganglion cells Bipolar cells Photoreceptor cells

dark adaptation

If you move from a bright place to a dark room, poor vision will temporarily take place until photoreceptors undergo ________.

More active than

In dim light, rods are ______ cones. Multiple choice question. as active as less active than more active than

rods; rhodopsin

In light adaptation, the eye is at first extremely sensitive to light as Blank______ are overwhelmingly activated, and the visual image is too bright and has poor contrast. However, the Blank______ is soon inactivated (sometimes said to be "bleached") as retinal dissociates from it. Multiple choice question. cones; calmodulin rods; rhodopsin rods; calmodulin cones; rhodopsin

outer;inner

In photoreceptor cells, the photopigment discs are found in the _____ segment, while mitochondria and other organelles are located in the ______ segment. Multiple choice question. outer; inner posterior; anterior anterior; posterior inner; outer

low; high; depolarized

In the dark, cGMP-phosphodiesterase activity inside photoreceptor cells is Blank______, cyclic GMP concentration is Blank______, and the membrane is Blank______. Multiple choice question. low; high; depolarized low; low; depolarized high; high; hyperpolarized high; low; depolarized

help light rays pass through the retina by acting like fiber-optic cables

In the eye, the function of the Müller cells is to Blank______. Multiple choice question. help with color vision by containing three different types of photopigments carry action potentials initiated by the photoreceptors through the optic nerve to the lateral thalamus reflect light rays back off of the choroid layer, giving photoreceptors a second chance to respond help light rays pass through the retina by acting like fiber-optic cables help with vision in dim light by containing high amounts of rhodopsin and being very sensitive to light

hyperopia

Inability to focus light rays from nearby objects on the retina is a characteristic of the condition ______. Multiple choice question. astigmatism cataract hyperopia myopia

myopia

Individuals who have difficulty focusing on objects that are further away have a condition called what?

astigmatism

Irregularity of the curvature of the lens or cornea of the eye causes a visual defect known as what?

Epithelium

Light rays that bypass the photoreceptors are absorbed by two pigmented layers in the back of the retina. These are the choroid and the pigment ________.

the eyeball being too long relative to the focusing power of the lens

Myopia is a condition caused by _____.

dark;light

Photoreceptors are depolarized in the Blank______ and hyperpolarized in the Blank______.

rhodopsin

Rod cells of the retina have a unique photopigment called ______. Multiple choice question. fovea choroid rhodopsin retinal kodachrome

photoreceptor cells

Rods and cones are examples of ______. Multiple choice question. photoreceptor cells components of tears myoepithelial cells suspensory ligament cells

sympathetic neurons innervating the iris

Stimulation of the ______ would cause the dilation of the pupil. Multiple choice question. sympathetic neurons innervating the lens parasympathetic neurons innervating the iris parasympathetic neurons innervating the lens sympathetic neurons innervating the iris

ciliary muscle

The accommodation reflex of the eye occurs due to contraction and relaxation of the what?

Retinal

The chromophore in all of the different types of photopigments found in the human eye is what?

ganglion cells, bipolar cells, amacrine cells, horizontal cells, photoreceptor cells, choroid

The correct order of the structures in the figure, beginning with the front of the retina on the far left to the optic nerve fibers on the far right is Blank______. Multiple choice question. photoreceptor cells, choroid, amacrine cells, bipolar cells, horizontal cells, ganglion cells ganglion cells, bipolar cells, amacrine cells, horizontal cells, photoreceptor cells, choroid horizontal cells, bipolar cells, photoreceptor cells, amacrine cells, ganglion cells, choroid bipolar cells, horizontal cells, amacrine cells, ganglion cells, choroid, photoreceptor cells choroid, photoreceptor cells, horizontal cells, bipolar cells, amacrine cells, ganglion cells

parasympathetic neurons innervating the iris

The pupil is constricted by increased activity of the ______. Multiple choice question. sympathetic neurons innervating the lens sympathetic neurons innervating the iris parasympathetic neurons innervating the iris parasympathetic neurons innervating the lens

presbyopia

The reduced ability to accommodate for near vision that commonly occurs with aging is called what?

True

True or false: The bleaching reaction of rhodopsin occurs when stepping from a dark place into a bright one.

pigment epithelium

Two layers at the back of the eye absorb stray light rays and prevent blurring of the visual image, the choroid layer and the what?

Cone cells Rode cells

What are the two principle types of photoreceptor cells?

rod cells

What is the photoreceptor cell that is extremely sensitive and is responsible for night vision?

Refraction

When a light ray passes from air into water its direction changes, a phenomenon called Blank______. Multiple choice question. resolution refraction reflection diffraction accommodation

Refraction

When diverging light rays enter a dense medium at an angle to its convex surface, the wave changes direction at an angle that depends on the density of the medium and the angle at which it strikes the surface. This bending of light waves is called what?

Negative

When light rays activate a photoreceptor, the cell's membrane potential becomes more ______. Multiple choice question. positive negative

Retina

When light waves diverging from a point on an object pass from air into the curved surfaces of the cornea and lens of the eye, they are refracted inward, converging back into a point on the what?

cGMP

Which of the following binds to cation channels on the inside of photoreceptor membranes, maintaining them in an open state? Multiple choice question. Retinal Transducin Phosphodiesterase cGMP Rhodopsin

Contraction of the ciliary muscle

Which of the following increases the refractive power of the lens? Multiple choice question. Contraction of the superior oblique muscle Relaxation of the medial rectus muscle Contraction of the medial rectus muscle Contraction of the ciliary muscle Relaxation of the superior oblique muscle Relaxation of the ciliary muscle

outer segment

Which part of the photoreceptor cell contains the photopigment molecules that absorb light? Multiple choice question. Outer segment Inner segment

Cornea

Which structure of the eye has the largest quantitative role in focusing light waves? Multiple choice question. Cornea Vitreous humor Lens Aqueous humor

presbyopia

With aging, accommodation for near vision becomes more difficult as the lens becomes less flexible. This condition is called what?

ganglion cells

the specialized cells which lie behind the bipolar cells whose axons form the optic nerve which takes the information to the brain