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Nervous System > Lecture 6.1: Special Senses – The Eye and the Ear > Flashcards

Lecture 6.1: Special Senses – The Eye and the Ear Flashcards

1
Q

How many fibres does the Optic nerve have?

A

> 1million

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2
Q

How many fibres does the Auditory nerve have?

A

30,000

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3
Q

What percentage of blindness is preventable?

A

50%

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4
Q

Name 4 preventable causes of blindness (4)

A
  • ARMD
  • Glaucoma
  • Cataracts
  • Diabetic Retinopathy
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5
Q

What is Phototransduction?

A

Process by which light energy is translated into electrical
energy

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6
Q

What are the 2 Photoreceptors found in the Eye?

A

Rods and Cones

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7
Q

What are Rods sensitive to? Where are they found?

A
  • Sensitive to low level light – night vision
  • All areas of retina except fovea
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8
Q

What are Cones sensitive to? Where are they found?

A
  • 3 different photopigments – red, green and blue
  • Daytime vision
  • Highest density at fovea
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9
Q

What is Myopia?

A
  • Short-sightedness is a very common eye condition
    where you cannot see objects far away clearly
  • Eyeball too long or lens too curved
  • Image formed in front of the retina
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10
Q

What is Hypermetropia?

A
  • Long-sightedness is where you find it hard to see
    things nearby, but you can see things far away clearly
  • Eyeball too short or lens too flat
  • Image formed behind the retina
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11
Q

What is Visual Acuity?

A
  • How well we can resolve fine detail
  • Snellen chart
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12
Q

What is the Ishihara Test?

A
  • Test of colour vision
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13
Q

What do you check when assessing vision? (8)

A
  • Visual acuity
  • Ishihara test
  • Pupillary reflexes
  • Blind spot
  • Ophthalmoscopy (retina, optic nerve)
  • Visual fields
  • Eye movements
  • Ocular alignment
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14
Q

Why is an Ophthalmoscopy done?

A
  • Visualisation of the vitreous and retina
  • Can use pupillary dilatation
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15
Q

What does Black blobs in the Vitreous mean?

A

Vitreous haemorrhage

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16
Q

What is found in the Fovea?

A

Region of highest density of photoreceptors in retina

17
Q

What is Presbyopia?

A
  • Lens becomes stiffer with age resulting in a decrease
    in accommodation/focusing
  • Close objects no longer focused onto the retina
  • Corrected with convex lens’ of increasing strength
18
Q

Who uses a convex lens?

A

People with farsightedness

19
Q

Who uses a concave lens?

A

People with shortsightedness

20
Q

Corneal Reflex

A
  • Also known as the blink reflex or eyelid reflex
  • It is an involuntary blinking of the eyelids elicited by
    stimulation of the cornea
  • Caused by a loop between the trigeminal sensory
    nerves and the facial motor (VII) nerve innervation of
    the orbicularis oculi muscles
21
Q

Pupillary Reflex

A

An autonomic reflex that constricts the pupil in response to light, thereby adjusting the amount of light that reaches the retina

22
Q

Optic Pathway (7)

A
  • Eye
  • Optic Nerve
  • Optic chiasm
  • Optic tract
  • Lateral geniculate nucleus
  • Optic radiation
  • Visual cortex
23
Q

Conditions that affect the Eye: Front

A
  • Cataract
  • Glaucoma
  • Vitreous Humour (flashes and floaters)
24
Q

Conditions that affect the Eye: Retinal Diseases (5)

A
  • Retinitis Pigmentosa
  • Retinal Detachment
  • Red/Green Colour Blindness
  • Diabetic Retinopathy
  • ARMD (age related macular degeneration)
25
Q

Conditions that affect the Eye: Optic Nerve (2)

A
  • Multiple Sclerosis
  • Raised ICP (Intracranial Pressure)
26
Q

Conditions that affect the Eye: Nervous (4)

A
  • Visual Field Defects
  • CVA (cerebrovascular accident)
  • Pituitary Tumour
  • RAPD (relative afferent pupillary defect)
27
Q

Conductive Hearing Loss

A

When sounds are unable to pass from your outer ear to your inner ear

28
Q

Sensorineural Hearing Loss

A

Occurs if the sensitive hair cells inside the cochlea are damaged, or as a result of damage to the auditory nerve

29
Q

What happens in the Cochlea?

A
  • Vibration of stapes at oval window→ vibrations of
    perilymph in scala vestibuli
  • Transmitted to endolymph in cochlear duct and spiral
    organ of Corti on basilar membrane
  • Hair cells stimulated→impulses travel along CNVIII to
    brain
30
Q

How does Auditory Transduction work?

A
  • 4 rows of hair cells
  • 1 inner hair cells row (provide most of the signal to CN
    VIII)
  • 3 outer hair cell rows (role in modulating the response
    of the inner hair cells)
31
Q

Auditory Pathway: Primary (Lemniscal) Pathway

A

Main pathway through which auditory information reaches the primary auditory cortex

32
Q

Auditory Pathway: Non-Lemniscal Pathway

A

Mediating unconscious perception eg. attention, emotional response, and auditory reflexes

Nervous System (18 decks)

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