Development of the eye Flashcards

1
Q

What is the optic vesicle?

A

An outgrowth of the eye from the neural tube

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2
Q

What is the lens placode?

A

thickened portion of ectoderm that acts as a precursor to the lens

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3
Q

What is the function of the outer layer (tunicae)?

A

Dense and tough collagen tissue, it protects and holds the eyeballs shape

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4
Q

What is the function of the middle (vascular) tunic?

A

Contains the blood vessels and also the structures that hold the lens in place/ regulate pupil size

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5
Q

What does the fibrous tunic consist of?

A

The sclera and the cornea

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6
Q

What does the vascular tunic consist of?

A

Choroid, Ciliary body and the iris

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7
Q

What is another word for vascular tunic?

A

Uvea

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8
Q

What produces the aqueous humour?

A

It is produced by the ciliary epithelium, this fluid then fills the front chambers of the eye

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9
Q

Where is the aqueous humour reabsorbed?

A

reabsorbed by the trabecular meshwork

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10
Q

What is glaucoma?

A

Too much fluid building up in the eye without proper drainage

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11
Q

What is the function of the nervous tunic?

A

Connected to the brain and converts light information to a nerve signal

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12
Q

What is the lens composed of?

A

clear, transparent cells contained within an elastic capsule

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13
Q

What is cataracts?

A

clouding of the lens

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14
Q

Where does the eye sit in the skull?

A

within the bony orbit

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15
Q

What is the function of the bony orbit?

A

Houses and protects the eyeball

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16
Q

Binocular vision

A

In animals with front facing eyes, better depth perception but more limited field of view

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17
Q

Monocular vision

A

In animals with lateral facing eyes, little depth perception but better field of view

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18
Q

What are the extra-occular muscles?

A

Act together to produce/ coordinate eye movements

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19
Q

What are eye-lids?

A

skin folds that cover the eye

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20
Q

Where do the tear glands drain?

A

Drains through nasolacrimal duct into nose

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21
Q

What keeps the third eye retracted?

A

Smooth muscle under a sympathetic influence

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22
Q

What is the function of the retractor bulbi?

A

pulls the eye back into the head

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23
Q

What is the cartilage at the third eyelid like?

A

T-shaped cartilage

24
Q

Where does the lens placode sit?

A

Inside of the optic cup

25
Q

What does the overlying ectoderm become?

A

The cornea

26
Q

What do the two layers of the optic cup go on to become?

A

The neural and pigmented retina

27
Q

What is the function of the cornea?

A

transparent part at the front of the eye, it allows light to enter

28
Q

What is the vascular tunic also known as?

A

The uvea

29
Q

What is the choroid and what artery supplies it?

A

The choroid is a highly vascular part at the back of the eyeball and is supplied by the opthalmic artery

30
Q

What attaches the ciliary muscle to the lens?

A

Zonules/ Zonulas

31
Q

Where is the vitreous chamber found?

A

Behind the lens

32
Q

What are the three main functions of the eyelid?

A

Blocks light, Protects the cornea and keeps the surface moist

33
Q

What does the lens vesicle induce?

A

The lens vesicle induces the overlying ectoderm to become the cornea

34
Q

What does the mesenchyme surrounding the optic cup become?

A

The fibrous and vascular layers

35
Q

What does the optic stalk become?

A

The optic stalk becomes the optic nerve

36
Q

What do the hyaloid vessels leave behind once they regress?

A

They leave behind a non-functional hyaloid canal

37
Q

What is the main function of the choroid?

A

To supply nutrients/nourish to the outer retina

38
Q

What is the iris a continuation of?

A

The iris is a continuation of the ciliary body

39
Q

What is the name of the smooth muscle that keeps the third eyelid retracted under sympathetic influence?

A

m. orbitalis

40
Q

What is the function of the top layer of the eye lid?

A

It is a lipid top layer (tarsal glands) and it prevents evaporation

41
Q

What is the function of the middle layer of the eyelid?

A

It is a watery middle layer (lacrimal gland and third eyelid) and it nourishes the cornea

42
Q

What is the function of the bottom layer of the eyelid?

A

Mucous bottom layer that sticks tear film to the eye

43
Q

What is a species difference of the retina in birds?

A

There are fewer blood vessels to ‘block’ the retina, therefore birds have better vision

44
Q

What are sclerotic rings and what are there function?

A

Sclerotic rings are bony plates within the eye and they function to hold the eyeball shape and counteract water pressure

45
Q

What is the name of the artery that supplies the choroid?

A

opthalmic artery

46
Q

What is the main function of the lens?

A

To keep objects in focus (accommodation)

47
Q

What are suspensory ligaments attached to?

A

Zonulas

48
Q

Where is aqueous humour reabsorbed?

A

trabecular meshwork at the iridocorneal angle

49
Q

What is derived from the outer part of the optic cup?

A

The pigmented layer of the retina

50
Q

Where do all axons from the ganglion converge?

A

at the optic nerve that takes information to the brain

51
Q

Which tear gland layer contains the third eyelid and lacrimal duct?

A

The watery middle layer

52
Q

What is the function of the mucous bottom layer of the tear gland?

A

It sticks tear films to the eye

53
Q

What is the purpose of blinking?

A

spreads tear films over the eye

54
Q

What is the organ that separates the anterior and posterior chambers?

A

The lens/ the suspensory ligaments holding it

55
Q

What is the name of the device that allows you to view the tympanic membrane when the auditry canal is straightened?

A

otoscope

56
Q

What is the name of the glands that line the external ear?

A

sebacous and modified apocrien (ceruminous) glands