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Y2 Neuroscience and Mental Health > Structure and Function of the Eye > Flashcards

Structure and Function of the Eye Flashcards

1
Q

Label the anterior view of the eye

A 
Upper eyelid
Palpebral fissure
Lateral canthus
Medial canthus
Lower eyelid 
Pupil
Iris
Sclera
Caruncle
Limbus
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2
Q

What are the types of tears

A

Basal tears
Reflex tears
Crying/emotional tears

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3
Q

Describe the reflex pathway for tears

A

Afferent - corner CN V1 (ophthalmic branch of the trigeminal)
Efferent - parasympathetic
NT - acetylcholine

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4
Q

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A

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5
Q

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A

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6
Q

What are the functions of the tear film

A

Maintains smooth cornea-air surface
Provides oxygen supply
Removal of debris
Bactericide

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7
Q

Describe the structure of the tear film

A

Superficial oily
Aqueous tear film
Mucinous later on the corneal surface

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8
Q

Describe the conjunctiva

A

Thin, transparent tissue that covers the outer surface of the eye
Begins at the outer edge of the cornea, covers the visible part of the eye and lines the inside of the eyelids
Nourished by tiny blood vessels (invisible to the eye)

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9
Q

In which conditions may the vessels of the eye become visible

A

Conjunctivitis

Uveitis

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10
Q

Label a sagittal section of the eye

A 
Cornea 
Iris 
Ciliary body 
Rectus muscle 
Retina 
Choroid 
Sclera
Optic nerve
Optic disc 
Vitreous
Lens
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11
Q

Describe the coat of the eye

A 
Anterio-posterior diameter - 24mm 
3 layers
Sclera - hard and opaque 
Choroid - pigmented and vascular 
Retina - neurosensory tissue
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12
Q

Describe the sclera

A

Tough, opaque tissues that serves as the eye’s protective outer coat
High water content

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13
Q

Describe the cornea

A

Transparent, dome-shaped window covering the from
Refractive surface, providing 2/3 eye focusing power
Low water content

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14
Q

-

A

-

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15
Q

Describe the layers of the cornea

A 
1 - epithelium 
2 - Bowman's membrane
3 - stroma
4 - Descemet's membrane
5 - endothelium
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16
Q

Describe the storm layer of the cornea

A

Regularity contributes to transparency
Corneal nerve endings provides sensation and nutrients for healthy tissue
No blood vessels in normal cornea

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17
Q

Describe the endothelial layer o the cornea

A

Pumps fluid put of the cornea and prevents

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18
Q

Describe the uvea

A

Vascular coat of the eye ball
Lies between sclera and retina
Composed of iris, ciliary body and choroid
They are connected and a disease of one part will affect the others

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19
Q

Describe the choroid

A

Lies between retina and sclera

composed of layers of blood vessels that nourish the back of the eye

20
Q

Describe the iris

A

Coloured part of the eye
Controls light levels in the eye
Embedded with tiny muscles that dilate and constrict the pupil size

21
Q

Describe the structure of the lens

A

Outer acellular capsule
Regular inner elongated cell fibres - transparency
May lose transparency with age e.g. cataracts

22
Q

Descriebe the function of the lens

A 
Transparency (regular structure)
Refractive power (1.3 power, higher refractive index than aqueous fluid and vitreous)
Accommodation (elasticity)
23
Q

What are lens zonules

A

Lens is suspended by a fibrous ring (lens zonules) consisting of passive connective tissue

24
Q

Describe the retina

A

Thin layer of tissue lining the inner part of the eye
Responsible for capturing light rays that enter the eye
Light impulses are then sent to the brain via the optic nerve

25
Q

Describe the optic nerve

A

Transmits electrical impulses from the retina to brain
Connects to the back of the eye near the macula
Visible portin = optic disc

26
Q

Describe the macula

A

Located roughly in the centre of the retina. temporal to the optic nerve
Small and highly sensitive part of the retina - central vision
Fovea is the centre of the macula
Allows for appreciating detail (reading)

27
Q

Describe the anterior chamber

A

Froms the lens forwards
Between cornea and lens
Filled with clear aqueous fluid
Supplies nutrients

28
Q

What is the ciliary body made up of

A

Ciliar muscle
Ciliary epithelium
Dilator
Sphincter

29
Q

What are the functions of the ciliary body

A

Secretes aqueous fluid into the eye

Aqueous fluid supplies nutrients

30
Q

Describe the ciliary body

A

Intraocular fluid flow anteriorly into the anterior chamber along
Normal pressure = 12-21

31
Q

-

A

Canal of scheme - 80-90%

Uveal -sclera outlaw

32
Q

What is glaucoma

A

Medical condition of sustained raised intraocular pressure

Retinal ganglion cell death and enlarged optic disc cupping

33
Q

What can glaucoma lead to

A

Visual field loss

Blindness

34
Q

What are the types of glaucoma

A

Primary open angle glaucoma

Closed angle glaucoma

35
Q

What is the blind spot

A

Where the optic nerve meets the retina there are no light sensitive cells. It is a blind spot.

36
Q

Describe primary open angle glaucoma

A

Trabecular Meshwork Dysfunction

37
Q

Describe closed angle glaucoma

A

Increased pressure pushing the iris/lens complex forwards, blocking the trabecular meshwork – vicious cycle
Risk factors - small eye (hypermetropia), narrow angle at trabecular meshwork
May present with sudden painful red eye with acute drop in vision
Can be treated with peripheral
laser iridotomy to create a drainage hole on the iris

38
Q

Describe the fovea

A

most sensitive part of the retina.

Has the highest concentration of cones, but a low concentration of rods.

39
Q

Describe central vision

A

Detail Day Vision, Colour Vision – Fovea has the highest concentration of cone photoreceptors
to navigate in environment, patient may
need white stick even with perfect visual acuity

40
Q

Describe peripheral vision

A 
Shape, Movement, Night Vision
– Navigation Vision
– Assessed by Visual Field 
Assessment – Extensive loss of Visual Field – unable
Central and Peripheral Vision
 –
41
Q

Describe the structure of the retina

A

Outer Layer – Photoreceptors (1st Order Neuron) – Detection of Light Middle Layer – Bipolar Cells (2nd Order Neurons) – Local Signal Processing to
improve contrast sensitivity, regulate sensitivity
Inner Layer – Retinal Ganglion Cells (3rd Order Neurons) – Transmission of Signal from the Eye to the Brain

42
Q

macula and fovea

A

-

43
Q

Describe the rod receptor

A

-

44
Q

Describe the cone receptor

A

-

45
Q

Whichisthe commonest form of colour vision deficiency in humans

A

Red-green confusion

Y2 Neuroscience and Mental Health (22 decks)

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