The Eye Flashcards

1
Q

How does the retina generate impulses

A

Through a series of chemical reactions which are then conducted along the optic nerve

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2
Q

How are the impulses from the retina carried on

A

By fibres of the optic tract to synapse with cells in the lateral geniculate nucleus of the thalamus
Axons then reach the primary visual cortex in the occipital lobe through optic radiation

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3
Q

What are the 6 extra ocular muscles of the eye

A

Medical and lateral recti
Superior and inferior recti
Superior and inferior obliques

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4
Q

What are the 3 nerve supplies for the extra ocular muscles

A

Oculomotor
Trochlear
Abducens

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5
Q

What is the laevator palpebrae superioris innervated by

A

The oculomotor nerve

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6
Q

What are the 3 main functions of the eyelids

A

Provide mechanical protection
Blinking facilitates replenishing of the protective tear film
Contains glands which secrete outermost lipid layer of tear film

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7
Q

What is the function of the iris

A

Regulate the amount of light that can enter the retina

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8
Q

What is the function of the cornea

A

Protecting the eye from outside infiltrates and ultraviolet radiation

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9
Q

What is the function of the pupil

A

Allow light to enter the eye so it can be focused on the retina to being the process of sight

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10
Q

What is the function of the lens

A

Transmit and focus the light onto the retina in order to create clear images of objects at various distances

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11
Q

What is the function of the sclera

A

Helps maintain eye shape and protects from injury

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12
Q

What is the function of the eyes ciliary body

A

Produces the fluid in the eye called aqueous humor

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13
Q

What is the function of the choroid in the eye

A

Supplies oxygen and nutrients to outer retina, light absorption, thermoregulation and modulation of intraocular pressure

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14
Q

What is the function of the macula

A

Translates light that enters your eye into the images you see

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15
Q

What is the function of the retina

A

Converts light that enters the eye into electrical signals which the optic nerve sends to the brain the create the image

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16
Q

What is the function of the vitreous

A

Maintain the round shape of the eye

17
Q

How does the parts of the eye work together

A

Light passes through the cornea which can bend the light to help focus the eye - some light enters the eye at the opening called the pupil - iris controls how much light the pupil lets in - light passes through the lens which works together with the cornea to focus light correctly on the retina - photoreceptors turn the light into electrical signals

18
Q

What are rod cells for

A

More abundant
Cylindrical shaped
High sensitivity to light
Function in night vision
Low visual acuity
Absent at the fovea

19
Q

What are cone cells for

A

Fewer in number
Conical shaped
Low sensitivity to light
Responsible for colour vision
Localised at fovea

20
Q

What is the fovea

A

A small depression within the neurosensory retina where visual acuity is the highest

21
Q

What is the extra cranial pathway of the optic nerve

A

Formed by the convergence of axons from the retinal ganglion cells - leave the bony orbit via optic canal (passage through sphenoid bone) and enters cranial cavity running along the surface of the middle cranial fossa

22
Q

What is the optic chiasm

A

Within the middle cranial fossa the optic nerves from each eye unite to form this

23
Q

What happens at the optic chiasm

A

Fibres form the nasal (medial) half of each retina cross over to the contralateral optic tract while fibres from the temporal (lateral) halves remain ipsilateral

24
Q

What does the left optic tract contain

A

Fibres from the left temporal (lateral) retina and the right nasal (medial) retina

25
Q

What does the right optic tract contain

A

Fibres from the right temporal retina and the left nasal retina

26
Q

What is conjunctiva

A

Formed of a mucus membrane that covers the inner surface of both eyelids covers the anterior portion of the sclera and ends at the corneo scleral junction

27
Q

What is the appearance of viral conjunctivitis

A

Clear, watery discharge

28
Q

What is the appearance of bacteria conjunctivitis

A

Mucopurulent discharge

29
Q

What is keratoconus

A

A non inflammatory usually bilateral protrusion of the cornea

30
Q

What is glaucoma

A

Occurs due to faulty drainage of aqueous humor leading to build up of pressure manifests as loss of peripheral vision

31
Q

What is cataract

A

Caused by opacification clouding of the crystalline lens