Special Senses (Eye) Flashcards

1
Q

What is the eye?

A

organ of vision very important to human survival

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2
Q

What is contained within the eye?

A

more than ½ of sensory receptors of human body

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3
Q

What is 40% of the cerebral cortex for?

A

devoted to processing of visual information

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4
Q

What is the eyeball supported and protected by?

A

accessory structures including eyelids, extraocular muscles, and lacrimal apparatus

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5
Q

Eyeball

What is the shape?

A

symmetric, spherical structure

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6
Q

Eyeball

What is the eyeball surrounded by?

A

layer of loose connective tissue that allows its relatively free movement within orbital cavity

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7
Q

Eyeball

What are the 3 layers or tunics of the eyeball?

A

fibrous layer (tunic)
vascular layer
nervous layer

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8
Q

Eyeball - Fibrous Layer (Tunic)

What is the fibrous layer (tunic)?

A

outermost layer

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9
Q

Eyeball - Fibrous Layer (Tunic)

What is the sclera?

A

posterior ⅚ of fibrous layer made up of white-ish dense connective tissue

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10
Q

Eyeball - Fibrous Layer (Tunic)

What does the sclera do?

A
  • protects inner parts of eyeball
  • serves as attachment site for extraocular muscles
  • maintains shape of eyeball
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11
Q

Eyeball - Fibrous Layer (Tunic)

What penetrates the posterior aspect of the sclera?

A
  • optic nerve

- blood vessels

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12
Q

Eyeball - Fibrous Layer (Tunic)

What is the cornea?

A

anterior ⅙ of layer that is transparent, lacks blood vessels, and is covered by conjunctiva

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13
Q

Eyeball - Fibrous Layer (Tunic)

What does the cornea do?

A

contribute in focusing light onto retina

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14
Q

Eyeball - Vascular Layer

What is the vascular layer?

A

middle layer that consists of 3 parts

  • choroid
  • ciliary body
  • iris
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15
Q

Eyeball - Vascular Layer

What is the choroid?

A

forms posterior ⅚ of layer and lines inner surface of sclera

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16
Q

Eyeball - Vascular Layer

What does the choroid do?

A
  • highly vascularized and nourishes retina

- carries melanin pigments that absorbs light rays and prevents reflection of light within eyeball

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17
Q

Eyeball - Vascular Layer

What is the ciliary body?

A

anterior continuation of choroid

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18
Q

Eyeball - Vascular Layer

What does the ciliary body do?

A

secretes aqueous humour and modifies convexity of lens

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19
Q

Eyeball - Vascular Layer

What is the core of the ciliary body formed by?

A

ciliary muscle (circular smooth muscles fibers)

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20
Q

Eyeball - Vascular Layer

What are suspensory ligaments?

A

delicate fibres stretched between inner surface of ciliary body, and circumference of lens

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21
Q

Eyeball - Vascular Layer

What does contraction of ciliary muscle do?

A

alters convexity of lens to adapt for near vision

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22
Q

Eyeball - Vascular Layer

What does relaxation of ciliary muscle do?

A

alters convexity of lens to adapt for far vision

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23
Q

Eyeball - Vascular Layer

What is the iris?

A

anterior ⅙ of vascular layer

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24
Q

Eyeball - Vascular Layer

What does the iris form?

A

vertical disc in front of lens, and behind cornea

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25
Eyeball - Vascular Layer What is the core of the iris formed by?
smooth muscle fibers arranged in circular or radial manner
26
Eyeball - Vascular Layer What is the pupil?
central opening of iris whose diameter is altered by contraction of smooth muscles fibers, which determines amount of light entering eyeball
27
Eyeball - Vascular Layer What does parasympathetic activation of the iris do?
contracts circular muscle fibers that entails constriction of pupil
28
Eyeball - Vascular Layer What does sympathetic activation of the iris do?
contracts radial muscle fibers that leads to dilation on pupil
29
Eyeball - Vascular Layer What does the iris carry?
melanin pigments, and the amount determines eye colour
30
Eyeball - Nervous Layer How many parts of the nervous layer are there?
2
31
Eyeball - Nervous Layer What is the retina?
posterior ¾ of nervous layer that carries photoreceptors that are sensitive to light
32
Eyeball - Nervous Layer Describe the anterior ¼ of the nervous layer.
doesn’t have any photoreceptor, but carries pigments and lines ciliary body and posterior surface of iris
33
Eyeball - Nervous Layer Where does the optic nerve leave the retina?
optic disc (blind spot), which lacks photoreceptors
34
Eyeball - Nervous Layer What is the macula lutea?
situated lateral to optic disc, and is very sensitive to light due to abundance of colour detecting photoreceptors
35
Eyeball - Nervous Layer What is the fovea centralis?
center of macula lutea that contains highest concentration of these colour detecting photoreceptors
36
Lens What is the lens?
transparent, biconvex, elastic body that lacks blood vessels
37
Lens Where is the lens?
posterior to iris
38
Lens What holds the lens in place?
suspensory ligaments that act as tendons of ciliary muscles
39
Interior of Eyeball What are the 3 chambers?
anterior chamber posterior chamber vitreous chamber
40
Interior of Eyeball Where is the anterior chamber?
lies between cornea and iris
41
Interior of Eyeball What is the anterior chamber filled with?
aqueous humour (a clear fluid)
42
Interior of Eyeball What does aqueous humour do?
- cushions lens and cornea | - provides transport system for nutrients and waste materials
43
Interior of Eyeball Where is the posterior chamber?
lies behind iris and in front of lens, and is continuous with anterior chamber through pupil
44
Interior of Eyeball What is the posterior chamber filled with?
aqueous humour, that is secreted by ciliary body
45
Interior of Eyeball Where does aqueous humour flow in the posterior chamber?
fills posterior chamber, flows through pupil, fills anterior chamber, and eventually drains into canal of Schlemm (scleral venous sinus) at junction of sclera and cornea
46
Interior of Eyeball Where is the vitreous chamber?
lies between lens and retina
47
Interior of Eyeball What is the vitreous chamber filled with?
vitreous body (vitreous humour) - clear jelly-like substance
48
Interior of Eyeball What does vitreous body (vitreous humour) do?
- helps maintain shape of eyeball - cushions lens - holds retina against choroid
49
Interior of Eyeball When does vitreous body (vitreous humour) form?
during embryonic life
50
Interior of Eyeball Compare vitreous body (vitreous humour) vs. aqueous humour.
vitreous body (vitreous humour) does not undergo constant turnover, unlike aqueous humour
51
What are the 3 accessory structures of the eye?
- eyelids (palpebrae) - lacrimal apparatus - extraocular muscles
52
Eyelids (Palpebrae) What are eyelids?
thin skin folds in front of eyeball that protect eye against excessive light and foreign objects
53
Eyelids (Palpebrae) What is the core of the eyelids formed by?
tarsal plate (fibroelastic plate) and skeletal muscles
54
Eyelids (Palpebrae) What is the inner surface lined by?
conjunctiva - mucous membrane that reflects on eyeball to cover cornea
55
Eyelids (Palpebrae) What is found at the free margin of eyelids? (3)
eyelashes sweat glands sebaceous glands
56
Lacrimal Apparatus What is the lacrimal apparatus composed of? (4)
group of structures that produce and drain tears - lacrimal gland - lacrimal canaliculi - lacrimal sac - nasolacrimal duct
57
Lacrimal Apparatus Where is the lacrimal gland?
occupies superolateral part of orbital cavity
58
Lacrimal Apparatus What does the lacrimal gland do?
release tears on surface of eye – tears are swept across ocular surface by blinking movements of eyelids and are collected at medial corner of eye
59
Lacrimal Apparatus What are the lacrimal canaliculi?
pair of small tubes on medial corner of eye that drain tears into lacrimal sac
60
Lacrimal Apparatus What is the lacrimal punctum?
opening of lacrimal canaliculi
61
Lacrimal Apparatus What is the lacrimal sac?
membranous sac that fills lacrimal groove of lacrimal bone, and receives tears from lacrimal canaliculi
62
Lacrimal Apparatus What is the nasolacrimal duct?
distal continuation of lacrimal sac which empties into lateral wall of nasal cavity at inferior nasal meatus
63
Extraocular Muscles What are extraocular muscles?
extrinsic muscles of eye that arise from different parts of orbit, and insert to sclera skeletal muscles that move eyeball in different directions
64
Extraocular Muscles What are the intrinsic muscles of the eye?
smooth muscles of iris and ciliary body