Lab Unit 15 - Special Senses: Vision

Question 1

ASTIGMATISM

Answer 1

Irregularities in the surfaces in the cornea and/ or the lens. These irregularities decrease visual acuity because these structures are unable to focus light precisely on the retina.

Astigmatism test: wheel with lines and numbers, looks like a clock. All lines should appear equally distant and black. If any of the lines appear blurry or gray, astigmatism may be present.

Question 2

PALPEBRAL CONJUNCTIVA

Answer 2

Thin mucous membrane that lines the internal surface of the palpebrae (eyelids). This is called the palpebral conjunctiva.

Question 3

BULBAR CONJUNCTIVA

Answer 3

Where the mucous membrane contact the eyeball, it curls around and becomes the bulbar conjunctiva. It lines much of the eyeballs superficial surface.

Question 4

6 EXTRINSIC EYE MUSCLES

Answer 4

1. Superior rectus muscle
2. Medial rectus muscle
3. Lateral rectus muscle
4. Inferior rectus muscle
5. Superior oblique muscle
6. Inferior oblique muscle

Question 5

Which 4 refractive media does light have to pass before it hits the retina?

Answer 5

1. The cornea
2. The aqueous humor
3. The lens
4. The vitreous humor

Note: the cornea and the lens have the greatest refractive power.

Question 6

MYOPIA

Answer 6

Another word for nearsighted

Question 7

EMMETROPIC

Answer 7

The distance at which the normal eye can read. 20/20 vision

Question 8

20/15 VISION

Answer 8

You can see at 20 feet what a normal eye sees at 15 feet. If you have 20/15 vision, you have better than normal vision.

Question 9

HYPEROPIA

Answer 9

Another word for farsighted

Question 10

MYOPIC

Answer 10

If someone has less than normal acuity, such as 20/40

Question 11

LATERAL RECTUS MUSCLE

Answer 11

Moves the eyeball laterally

Question 12

MEDIAL RECTUS MUSCLE

Answer 12

Moves the eyeball medially

Question 13

SUPERIOR RECTUS MUSCLE

Answer 13

Moves the eyeball superiorly

Question 14

INFERIOR RECTUS MUSCLE

Answer 14

Moves the eyeball inferiorly

Question 15

SUPERIOR OBLIQUE MUSCLE

Answer 15

Moves the eyeball inferiorly and laterally

Question 16

INFERIOR OBLIQUE MUSCLE

Answer 16

Moves the eyeball superiorly and laterally

Question 17

LENS

Answer 17

One of the structures in the eye that refracts (bends) light coming into the eye to focus it. The lens is also the boundary separating the anterior and posterior cavities.

Question 18

ANTERIOR CAVITY

Answer 18

The cavity anterior to the lens, filled with watery fluid called aqueous humor.

Question 19

AQUEOUS HUMOR

Answer 19

Aqueous humor is a watery fluid in the anterior cavity, anterior to the lens. It is produced relatively constantly and drained by the scleral venous sinus. Aqueous humor helps to refract light coming into the eye. Produced by the ciliary body in the vascular tunic.

Question 20

POSTERIOR CAVITY

Answer 20

Located posterior to the lens, the posterior cavity is filled with vitreous humor.

Question 21

VITREOUS HUMOR

Answer 21

Thicker than aqueous humor, vitreous humor is found in the posterior cavity, posterior to the lens. Vitreous humor is present at birth and remains relatively unchanged throughout life. Like aqueous humor, vitreous humor helps to refract light coming into the eye.

Question 22

FIBROUS TUNIC

Answer 22

The outermost layer of the eyeball, consists mostly of dense irregular collagenous connective tissue. It is avascular and consists of the sclera and the cornea.

Question 23

2 PARTS OF THE FIBROUS TUNIC

Answer 23

1. Sclera

2. Cornea

Question 24

SCLERA

Answer 24

The white part of the eyeball and makes up 5/6 of the fibrous tunic. It’s white because of the collagen fibers that contribute to its thickness and toughness.

Question 25

CORNEA

Answer 25

The cornea is clear and makes up the anterior 1/6 of the fibrous tunic. It is the fourth refractory medium of the eyeball.

Question 26

3 PARTS OF THE VASCULAR TUNIC

Answer 26

1. Choroid
2. Ciliary body
3. Iris

Question 27

VASCULAR TUNIC

Answer 27

Aka the uvea. The vascular tunic carries most of the blood supply to the tissues of the eye. Composed of the choroid, the ciliary body, and the iris.

Question 28

CHOROID

Answer 28

The choroid is highly vascular and makes up the posterior part of the vascular tunic. The choroid is brown to prevent light scattering in the eye.

Question 29

CILIARY BODY

Answer 29

The ciliary body is at the anterior aspect of the vascular tunic. It helps control the shape of the lens. The ciliary body also produces aqueous humor.

Question 30

IRIS

Answer 30

The pigmented iris is the most anterior portion of the vascular tunic. Its muscle fibers are arranged around the pupil, and when the fibers contract, the pupil either constricts or dilates. The iris also divides the anterior cavity into an anterior segment and posterior segment.

Question 31

2 PARTS OF THE SENSORY TUNIC

Answer 31

1. Rods

2. Cones

Question 32

SENSORY TUNIC

Answer 32

The sensory tunic consists of the retina and the optic nerve. Input from the sensory tunic is eventually delivered to the visual cortex in the occipital lobe of the brain.

Question 33

RETINA

Answer 33

In the sensory tunic, the retina is a thin, delicate structure that consists of photoreceptors (rods and cones), bipolar neurons, and ganglion cells.

Question 34

RODS

Answer 34

Photoreceptors in the retina, rods are scattered throughout the retina and are responsible for vision in dim light and for peripheral vision they can produce vision in black and white only.

Question 35

CONES

Answer 35

The second type of photoreceptors, cones are concentrated at the posterior portion of the retina. They are found in highest numbers in the macula lutea. cones are responsible for color and high-acuity (sharp) vision in bright light.

Question 36

MACULA LUTEA

Answer 36

Area where the highest numbers of cones are found.

Question 37

FOVEA CENTRALIS

Answer 37

Center of the macula lutea, area that contains only cones

Question 38

OPTIC DISC

Answer 38

Aka the blind spot, because it lacks photoreceptors (cones and rods), and cannot produce images.

Question 39

LACRIMAL GLAND

Answer 39

Part of the lacrimal apparatus, produces and drains tears.

Question 40

SENSATION

Answer 40

The detection of changes in the internal and external environments.

Question 41

PERCEPTION

Answer 41

Something of which you are consciously aware, such as the taste of food and the level of light in a room. This happens when information eventually gets taken to the cerebral cortex for integration and interpretation.

Question 42

ACCOMMODATION

Answer 42

The lens becomes rounder, an adjustment that allows the lens to provide the additional refraction necessary to focus light on the retina.

Question 43

RHODOPSIN

Answer 43

The purple pigment contained in the rods of the retina. When light strikes, it triggers a photochemical reaction that causes the rhodopsin to be split into its colorless precursor molecules - called bleaching of the pigment.

Question 44

PRESBYOPIA

Answer 44

A condition that happens when the elasticity of the lens decreases dramatically with age, resulting in difficulty in focusing for near or close vision

Question 45

BINOCULAR VISION

Answer 45

Aka two eyed vision - humans, cats, predatory birds, and most primates have this. Both eyes look in approximately the same direction, but they see slightly different views. Allows us to see in 3D and gives us depth perception.

Question 46

PANORAMIC VISION

Answer 46

Pigeons and fish have this, where the eyes are more on the sides of their head. Animals who have panoramic vision see in two different directions and have a panoramic field of view.

Question 47

PHOTOPUPILLARY REFLEX

Answer 47

A sudden illumination of the retina by a bright light causes the pupil to contract reflexively in direct proportion to the light intensity.