Eyes Flashcards

1
Q

What receptors are found in the eye?

A

Photoreceptors.

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2
Q

Which area of the brain processes visual information?

A

The Occipital lobe.

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3
Q

What is the function of the Lacrimal apparatus?

A

Production of Lacrimal fluid/tears.

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4
Q

State the flow of Lacrimal passage from the apparatus to the nasal cavity.

A

Lacrimal apparatus,
Lacrimal gland,
Lacrimal ducts to canal,
Lacrimal sac,
Nasolacrimal duct,
Nasal cavity.

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5
Q

What is the function of Lacrimal fluid?

A

Contains lysozyme which protects and cleanses the eyes.

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6
Q

What are the THREE tunics of the eye?

A

Fibrous tunic,
Vascular tunic,
Retina.

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7
Q

What does the fibrous tunic consist of?

A

Cornea & Sclera.

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8
Q

What does the Vascular tunic consist of?

A

Choroid, Ciliary body, Iris & Pupil.

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9
Q

What does the Retina consist of?

A

Photoreceptors- Rods & cones,
Optic disc,
Macula lutea,
Fovea Centralis

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10
Q

What is the function of the Cornea?

A

The transparent layer over the iris, protects the eye and has a curved shape to focus light. Accounts for 75% of refraction.

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11
Q

What is the function of the Sclera?

A

The white of the eyes,
Covers the entire eye except the cornea,
Provides shape & support.

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12
Q

What is the function of the Choroid?

A

Contains Melanocytes which produce melanin to absorb light.
Highly vascular.

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13
Q

What is the function of the Ciliary body?

A

Secretes aqueous humor,
ciliary muscles alter shape of the lens to focus image - Accomodation.

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14
Q

What is the function of the Iris?

A

The coloured portion of the eye - determined by melanin count.
Regulates the amount of light entering the eye.
Contains circular and radial smooth muscle.

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15
Q

What is the function of the Pupil?

A

The hole in the centre of the iris,
Point where light enters the eye.

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16
Q

What is the function of the Retina?

A

Forms the beginning of the visual pathway, Contains photoreceptors.
Contains the optic disc which is the location where the optic nerve exists the eye.

17
Q

What is the function of the Macula Lutea?

A

The exact centre of the posterior retina, contains the Fovea Centralis which contains only cones - highest area of visual activity.

18
Q

What is the difference between rods & cones?

A

Rods are specialised for black and white vision, aswell as shapes and movement. 120million in each eye.
Cones are specialised for colour vision. 6 million in each eye.

19
Q

What are the TWO cavities of the eye?

A

Anterior cavity,
Posterior cavity.

20
Q

What is the Anterior cavity?

A

Anterior to the lens,
Contains two chambers- Anterior chamber: between cornea & iris.
Posterior chamber: between iris & lens - contains aqueous humor which nourishes the lens and cornea.

21
Q

What is the Posterior cavity?

A

Lies between the lens and retina,
contains the vitreous body- a jelly like substance which maintains the shape of the eye.

22
Q

What is Intraocular pressure?

A

The pressure from Aqueous humor and Vitreous body.

23
Q

What are the FOUR steps of image formation?

A

Refraction,
Accomodation,
Pupil Constriction,
Convergence of the eyes.

24
Q

What is Refraction?

A

The Cornea & Lens bend light rays to focus an image on the Central fovea.

25
Q

What is Accomodation?

A

The change in shape of the Lens to allow sharp focusing of light into the Retina.

26
Q

What is Pupil constriction?

A

The smooth muscle of the Iris controls the amount of light entering the eye & helps prevent light scattering.

27
Q

What is Convergence of the eyes?

A

Medial movement of both eyes to focus on an object.

28
Q

What is the definition of Refraction?

A

A bending of light as it passes from one substance into another with a different density.

29
Q

Where does Refraction occur? and at what percent?

A

75% of Refraction occurs in the Cornea,
25% of Refraction occurs in the Lens.

30
Q

What is a potential abnormality that affects Refraction?

A

Presbyopia: Loss of lens elasticity which results in a decreased ability to focus on near objects.

31
Q

What is the process for focusing on a DISTANT object?

A

Ciliary muscles relax - pulls on suspensory ligament - which pulls on the Lens. Flat lens = reduced refraction.

32
Q

What is the process for focusing on a NEAR object?

A

Ciliary muscles contract - lessens tension on suspensory ligaments - lens thickens - increased curvature of lens= increased refraction.

33
Q

What is meant by Binocular vision?

A

Both eyes focus on the same object.

34
Q

What is the first step of vision transduction?

A

Absorption of light by photopigments in rods & cones.
This initiates an action potential.

35
Q

What is the flow of Visual pathway?

A

Visual info in the Optic nerve travels to the: Hypothalamus - establishes sleep patterns based on circadian rhythm.
Midbrain: Contains some visual reflex centres that control movement of the head, eyes & trunk in response to visual stimuli.
Primary Visual area: Location in which visual imagery is processed and associated.

36
Q

What are the THREE cranial nerves involved in the movement of Extrinsic eye muscles.

A

Oculomotor,
Abducens,
Trochlear.

37
Q

What are the accessory structures of the eye?

A

Eyelid,
Eyebrow,
Eyelash,
Canthus,
Lacrimal Caruncle.