Special Senses: The Eye and The Vision Flashcards

1
Q

Includes the eyes and other accessory structures that aid in sight. These include muscles, glands, and protective layers

A

The visual system

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2
Q

Size and shape of the eye

A

2.5 cm in diameter and has a spherical shape

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3
Q

→ Positioned anterior to the eye
→ Together with eyelashes, they protect the eyes from foreign objects

A

Eyelids (palpebrae)

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4
Q

The space between the eyelids

A

Palpebral fissure

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5
Q

Where the eyelids meet at the corners

A

Lateral commissure (lateral canthus) & Medial commissure (medial canthus)

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6
Q

a reddish-pink mound found within the medial canthus, containing sebaceous and sweat glands

A

Lacrimal caruncle

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7
Q

→ Located in the tarsal plate, a crescent-shaped connective tissue that helps maintain eyelid shape.
→ Produces oily secretions that lubricate the eyes and prevent tears from overflowing.

A

Tarsal (Meibomian) Glands

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8
Q
  • Located between the eyelashes and act as sweat glands.
  • Their ducts open near the base of the eyelashes.
A

Ciliary glands (glands of moll)

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9
Q

→ A mucous membrane that lines the eyelids and covers the outer surface of the eyeball.
→ Secreted mucus to keep the eyes lubricated and moist.

A

Conjunctiva

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10
Q

Covers the anterior white surface of the eye, connecting to the transparent cornea

A

Bulbar conjunctiva

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11
Q

Lines the inner surface of the eyelids

A

palpebral conjunctiva

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12
Q

→ is the white part of the eye, a tough, fibrous outer layer that provides
structure and protection.
→ It helps maintain the shape of the eye and serves as an attachment point for the extrinsic eye muscles.

A

Sclera

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13
Q

Includes the lacrimal glands and ducts, which produce and drain lacrimal fluid (tears).

A

Lacrimal apparatus

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14
Q

Cleanse, protect, moisten, and lubricate the eyes.
Contains: Dilute salt solution, mucus, antibodies, lysozymes

A

Tears (lacrimal fluid)

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15
Q

Pathway of tears

A

Lacrimal gland → Lacrimal canaliculus → Lacrimal sac → Nasolacrimal duct → Empties into the inferior meatus of the nasal cavity.

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16
Q

These six muscles control the movement of the eyes

A

Extrinsic eye muscles

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17
Q

Moves the eye laterally

A

Lateral rectus

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18
Q

Moves the eye medially

A

Medial rectus

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19
Q

Elevates the eye and turns it medially

A

Superior rectus

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20
Q

Depresses the eye and turns it medially

A

Inferior rectus

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21
Q

Elevates the eye and turns it laterally

A

Inferior oblique

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22
Q

Depresses the eye and turns it laterally

A

Superior oblique

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23
Q

Three layers that form the wall of the eyeball

A

Tunic

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24
Q

3 layers of tunic

A

Fibrous, vascular, sensory

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25
Q

Are fluids that fill the interior of the
eyeball

A

Humors

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26
Q

Divides the eye into two chambers

A

Lens

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27
Q

Consists of the sclera and cornea

A

Fibrous layer

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28
Q

→ Thick, white connective tissue layer and anteriorly we see this as the white part of the eye
→ To help maintain the shape of the eyeball and to help protect the internal structures of the eyeball and to provide an attachment point for the muscles that moves the eyeball

A

Sclera

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29
Q

→ The transparent central anterior region of the eyeball
→ It is the area that is exposed and prone to damage but it can repair itself easily
→ It allows the light to pass through it
→ It is the only human tissue that can be transplanted without the fear of rejection. This is because it is less immunologically active.

A

Cornea

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30
Q

→ The term means “membrane.”
→ It is a relatively thin layer located at the posterior part of the vascular layer.
→ The choroid is a blood-rich layer containing dark pigment, which prevents light from scattering within the eye

A

Choroid

30
Q

→ contains most of the blood vessels of the eyeball.
→ It consists of three main structures: the choroid, ciliary body, and iris.

A

Vascular layer

31
Q

→ It is located in the anterior part of the vascular layer and is modified from the choroid into two smooth muscle structures.
→ It is attached to the lens via the zonules (zonular fibers).
→ The function of this is to change the shape of the lens when focusing on objects.

A

Ciliary body

32
Q

Ciliary bodies are attached to the lens via

A

Zonules (zonular fibers)

33
Q

It is the pigmented layer that gives
the eye its color, which varies among
individuals.
→ It is composed of circular and radial
smooth muscle fibers.
→ At the center of the iris is the pupil,
the opening through which light
passes.
→ It acts as a diaphragm that regulates the amount of light entering the eye by controlling the size of the pupil

A

Iris

34
Q

In bright light or when focusing on close objects: The_______ contract, causing the pupil to constrict (get smaller).

A

Circular muscles

35
Q

In dim light or when focusing on distant objects: The _______ contract, causing the pupil to dilate (get larger).

A

radial fibers

36
Q

Composed of the retina.

A

Sensory layer

37
Q

The retina consists of two main layers:

A
  1. Outer pigmented layer
  2. Inner neural layer
38
Q

→ Composed of pigmented simple
cuboidal epithelial cells
→ Absorbs light: Prevents light from
scattering inside the eye.
→ Phagocytic activity: Acts as phagocytes to remove dead and damaged receptor cells.
→ Storage of Vitamin A: Essential for vision

A

Outer pigmented layer

39
Q

Contains different receptor cells
known as photoreceptors

A

Inner neural layer

40
Q

2 types of photoreceptors

A

Rods and cones

41
Q

How many cones do we have?

A

Approx. 6 to 7 million

41
Q

Respond to light, enabling vision

A

Photoreceptors

41
Q

→ Location: Primarily found on the
edges of the retina
→ Function:
○ Enable vision in dim light
○ Provide peripheral vision
→ do not perceive color; they are more sensitive to light.

A

Rods

42
Q

How many rods do we have?

A

Approx. 12 million

43
Q

→ Location: Densely concentrated in the center of the retina, particularly in the fovea centralis
→ Function:
○ Allow for detailed color vision
→ There are three types, each sensitive to different wavelength of light (red, green, and blue)

A

Cones

44
Q

Electric signals generated by
photoreceptors are transmitted via a two-neuron pathway, which includes:

A

Bipolar cells and Ganglion cells

45
Q

The signals from these cells (bipolar and ganglion) converge
and travel through the ______ to reach the brain.

A

optic nerve

46
Q

where the neural layer of the retina meets and optic nerves

A

Optic disc

46
Q

It is a crucial structure in the retina
where:
○ The central retinal artery
enters
○ The central retinal vein exits
○ Optic nerve exits the eye

A

optic disc

47
Q

Images focused on the optic disc cannot be seen because it lacks photoreceptors, creating a

A

blind spot

48
Q

→ Location: Lateral to the blind spot in the retina.
→ It is the area where light is most focused when looking directly at an object.
→ It contains only cone cells, which are more densely packed than in other areas of the retina.
→ This high concentration of
photoreceptors results in the greatest visual acuity or sharpest vision.

A

Fovea centralis

49
Q

→ Sensitive to short wavelengths of light.
→ Responds best to light around 420 nm (nanometers), which appears as blue.

A

blue cones

50
Q

→ Sensitive to medium wavelengths of light.
→ Most responsive to light around 530 nm, corresponding to green light.

A

Green cones

51
Q

→ Sensitive to long wavelengths of light.
→ Responds strongly to light around 560 nm, which is perceived as red.
→ Can also detect some yellow and
orange hues due to overlapping wavelengths with green cones

A

Red cones

52
Q

○ This is a flexible, crystal-like structure.

A

Lens

53
Q

What is the anterior side of the lens made of?

A

Layer of cuboidal epithelial

54
Q

What is the posterior side of the lens made of?

A

Long columnar epithelial cells known as lens fibers

55
Q

The lens is held in place by _______ attached to the ciliary body.

A

suspensory ligaments

56
Q

→ Located anterior to the lens
→ Contains aqueous humor, a clear,
watery fluid.

A

Anterior segment (aqueous segment)

57
Q

→ Located posterior to the lens.
→ Contains vitreous humor, a gel-like
substance.

A

Posterior segment (Vitreous segment)

58
Q

Location: Found in the anterior segment of the eye (aqueous segment). Watery fluid found between lens and cornea
Similar to blood plasma Composition:99.9% water (similar to blood plasma).
Helps maintain intraocular pressure (the pressure inside the eye). Provides nutrients for the lens and cornea , which are avascular (lack blood supply). Drains into the venous blood through the scleral venous sinus (canal of Schlemm) to prevent pressure buildup, which can lead to vision loss. Should be supplied at and drained at an equal rate to prevent build up of pressure that can cause vision loss

A

Aqueous humor

59
Q

Location: Found in the posterior segment of the eye (vitreous segment). Gel-like substance posterior to the lens
→ Prevents the eye from collapsing
→ Helps maintain intraocular pressure
→ Cannot be regenerated or actively
replenished.

A

Vitreous humor

60
Q

→ Instrument used to illuminate the
interior of the eyeball
→ Can detect diabetes, arteriosclerosis, degeneration of the optic nerve and
retina
→ Allows visualization of the retina,
optic disc, and internal blood vessels at the fundus (posterior wall of the eye).

A

Ophthalmoscope

61
Q

Bundle of axons that exit the back of
the eye carrying impulses from the retina to the brain

A

Optic nerve

62
Q

→ The location where optic nerves cross.
→ Fibers from the medial side of each eye cross over to the opposite side of the brain

A

Optic chiasma

63
Q

→ Fibers from the medial side ofeach
eye cross over to the opposite side of
the brain.
→ These tracts synapse with neurons in the thalamus.

A

Optic tracts

64
Q

Axons from the thalamus run to the
occipital lobe, synapsing with cortical cells where visual interpretation occurs (seeing).

A

Optic radiation

65
Q

→ Each eye perceives a slightly different view.
→ The field of viewoverlaps for both
eyes, enabling binocular vision.

A

Visual field

66
Q

Two-eyed vision provides depth
perception (three-dimensional vision) by fusing the two slightly different images into one.

A

Binocular vision

67
Q

A reflexive movement where the eyes
move medially when focusing on a close object

A

Convergence

68
Q

The pupils constrict in response to
bright light to protect photoreceptors.

A

Photopupillary reflex

69
Q

The pupils also constrict when viewing close objects to improve focus.

A

Accomodation pupillary reflex