Lab Unit 15 - Special Senses: Vision Flashcards

1
Q

ASTIGMATISM

A

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.

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2
Q

PALPEBRAL CONJUNCTIVA

A

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

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3
Q

BULBAR CONJUNCTIVA

A

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

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4
Q

6 EXTRINSIC EYE MUSCLES

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

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

A
  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.

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6
Q

MYOPIA

A

Another word for nearsighted

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7
Q

EMMETROPIC

A

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

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8
Q

20/15 VISION

A

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.

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9
Q

HYPEROPIA

A

Another word for farsighted

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10
Q

MYOPIC

A

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

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11
Q

LATERAL RECTUS MUSCLE

A

Moves the eyeball laterally

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12
Q

MEDIAL RECTUS MUSCLE

A

Moves the eyeball medially

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13
Q

SUPERIOR RECTUS MUSCLE

A

Moves the eyeball superiorly

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14
Q

INFERIOR RECTUS MUSCLE

A

Moves the eyeball inferiorly

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15
Q

SUPERIOR OBLIQUE MUSCLE

A

Moves the eyeball inferiorly and laterally

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16
Q

INFERIOR OBLIQUE MUSCLE

A

Moves the eyeball superiorly and laterally

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17
Q

LENS

A

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.

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18
Q

ANTERIOR CAVITY

A

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

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19
Q

AQUEOUS HUMOR

A

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.

20
Q

POSTERIOR CAVITY

A

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

21
Q

VITREOUS HUMOR

A

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.

22
Q

FIBROUS TUNIC

A

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.

23
Q

2 PARTS OF THE FIBROUS TUNIC

A
  1. Sclera

2. Cornea

24
Q

SCLERA

A

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.

25
Q

CORNEA

A

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

26
Q

3 PARTS OF THE VASCULAR TUNIC

A
  1. Choroid
  2. Ciliary body
  3. Iris
27
Q

VASCULAR TUNIC

A

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.

28
Q

CHOROID

A

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.

29
Q

CILIARY BODY

A

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.

30
Q

IRIS

A

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.

31
Q

2 PARTS OF THE SENSORY TUNIC

A
  1. Rods

2. Cones

32
Q

SENSORY TUNIC

A

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.

33
Q

RETINA

A

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

34
Q

RODS

A

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.

35
Q

CONES

A

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.

36
Q

MACULA LUTEA

A

Area where the highest numbers of cones are found.

37
Q

FOVEA CENTRALIS

A

Center of the macula lutea, area that contains only cones

38
Q

OPTIC DISC

A

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

39
Q

LACRIMAL GLAND

A

Part of the lacrimal apparatus, produces and drains tears.

40
Q

SENSATION

A

The detection of changes in the internal and external environments.

41
Q

PERCEPTION

A

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.

42
Q

ACCOMMODATION

A

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

43
Q

RHODOPSIN

A

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.

44
Q

PRESBYOPIA

A

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

45
Q

BINOCULAR VISION

A

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.

46
Q

PANORAMIC VISION

A

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.

47
Q

PHOTOPUPILLARY REFLEX

A

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