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Biomedicine II CNM (2024) > 18. Sense Organs > Flashcards

18. Sense Organs Flashcards

1
Q

What cranial nerve is used for hearing and balance?

A

Vestibulocochlear nerve
(CN 8 - connects to pons )

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2
Q

What connects the inner ear with the nasopharynx?

A

Eustachian tube

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3
Q

What makes up the outer ear and what are their functions?

A

Pinna - flap of elastic cartilage covered by skin that traps and directs sound waves into the ear.

External auditory canal - funnels sound waves.

Tympanic membrane (ear drum) - converts sound waves into mechanical vibrations

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4
Q

What is the middle ear?

A

A small air-filled cavity in the temporal bone containing the auditory ossicles.

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5
Q

List the THREE ‘ossicles’ found in the middle ear. And what is their function?

A

Malleus
Incus
Stapes

Transmits sound in the form of vibration from the tympanic membrane to the cochlea.

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6
Q

What does stapes attach to?

A

Oval window which connects to the cochlea.

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7
Q

Explain the role of the ‘stapedius’.

A

A small muscle that dampens large vibrations

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8
Q

Describe specifically the structure of the inner ear.

A

Also called the labyrinth. Consists of the outer bony labyrinth and the inner membranous labyrinth.

Contains 3 cavities:
- Semicircular canals
- Vestibule
- Cochlea

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9
Q

List TWO main functions of the inner ear.

A

Hearing & balance

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10
Q

Briefly describe the cochlea

A

Spiralled hollow chamber
Epithelial cells lined with hair cells containing stereocilia.

Fluid movement caused by vibrations cause stereocilia movement and initiates an electrical impulse.

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11
Q

Describe sound pathology

A

1) Pina concentrates sound waves into the auditory canal causing the tympanic membrane to vibrate.
2) Vibrations are transmitted through the middle ear by movement of the three auditory ossicles.
3) Stapes rocks the oval window causing fluid waves in the cochlear perilymph.
4) Pressure waves are transmitted into the cochlea causing the round window to bulge into the middle ear.
5) This pressure wave is transmitted into the endolymph.
6) This vibrates the basilar membrane and hair cells
7) Bending hair cell stereocilia creates a receptor potential generating an action potential.
8) Nerve impulses generated pass to the cerebrum via the vestibulocochlear nerve where sound is perceived.

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12
Q

Describe the difference between ‘pitch’ and ‘volume’ of sound waves.

A

Pitch = frequency of sound waves
Volume = amplitude of sound waves

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13
Q

Identify the decibel rating above which can contribute to hearing loss.

A

Above 85dB can being to impact hearing if there is prolonged exposure.

140dB can cause immediate damage and pain.

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14
Q

What is white noise and what’s it’s main function?

A

A constant noise that contains all the different frequencies of sound.

Used to mask other sounds.

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15
Q

List TWO functions of the Eustachian tube.

A

1) Equalise pressure
2) Drain mucus

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16
Q

Explain why children are more prone to middle ear infections.

A

Because it’s more horizontal so easier for bacteria to travel to the middle ear

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17
Q

What is the ‘otolithic’ membrane, and what is its structure?

A

Found in the semi-circular canals and vestibule. It’s a thick membrane that covers the stereocilia with a dense layer of calcium carbonate crystals on top.

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18
Q

List THREE ways in which the cerebellum can make postural adjustments to maintain balance.

A

1) Vestibular feedback from the inner ear
2) Visual feedback from the eye
3) Proprioceptors in skeletal muscles.

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19
Q

Explain why insufficient earwax can predispose to ear infections.

A

Ear wax contains lysosomes and oil that create an acidic, lubricating coat. This inhibits bacterial and fungal growth.

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20
Q

What is Otitis externa and some common causes?

A

aka swimmers ear
Inflammation of the outer ear

90% bacterial infection
Or fungal or allergic.

Common in swimmers
Diabetes mellitus
HIV

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21
Q

List the common signs and symptoms of otitis external

A

Pain especially when moving pinna.
Discharge
Swelling
Itching
Red, swollen auditory canal

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22
Q

What is Otitis media and it’s typical signs and symptoms?

A

Inflammation of the middle ear

Earache / pain
Bulging of tympanic membrane
Malaise, fever

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23
Q

What is secretory otitis media and how is it typically treated?

A

An effusion of the middle ear resulting from incomplete resolution of acute otitis media.

AKA Glue ear

A grommet is inserted into the eardrum to drain fluid and circulate air.

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24
Q

What is labyrinthitis and it’s typical signs and symptoms?

A

Otitis interna - Inflammation of the membranous labyrinth in the inner ear.

Sudden and severe vertigo (not triggered by movement)
Nausea and vomiting
Tinnitus.

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25
Q

Using definitions, compare ‘Meniere’s disease’ and ‘tinnitus’.

A

‘Meniere’s disease’ = a disorder of the inner ear caused by change in fluid volume in the labyrinth. Associated with progressive distention of the membranous labrynith

‘tinnitus’ = the perception of sound originating from with the head rather than outside.

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26
Q

List TWO signs and / or symptoms of Meniere’s disease.

A

Vertigo
Tinnitus
Hearing loss

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27
Q

List 3 natural approaches for meniere’s disease.

A

Low salt (reduce fluid build up in inner ear)
Regular exercise
Stress reduction
Smoking cessation
Address fatigue (common trigger)

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28
Q
  1. List TWO causes of the following:

a. Objective tinnitus
b. Subjective tinnitus

A

a. Objective tinnitus (caused by internal noise)
- Valve disease
- Tympanic muscles spasm

b. Subjective tinnitus (no biological origin)
- MS
- Tumour
- Infections
- Drug related

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29
Q

In dB, what are the measures for:
Mild hearing loss
Moderate hearing loss
Severe hearing loss
Profound hearing loss

A

Mild hearing loss - 25-40 dB
Moderate hearing loss - 41 - 70 dB
Severe hearing loss - 71 - 90 dB
Profound hearing loss - 90+ dB

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30
Q
  1. Describe the key difference between ‘conductive’ and ‘sensory’ hearing impairment.
A

Conductive = wave of sound / vibration / fluid becomes impaired. eg an ear canal obstruction.

Sensory - neurological or damage to sensory hairs

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31
Q

List 3 diseases that can cause hearing impairment

A

Measles
Meningitis
Mumps
Rubella
Chlamydia (loss in foetus)

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32
Q

What 2 treatments are there for hearing impairment?

A

Hearing aids
Cochlear impant

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33
Q

What cranial nerve is responsible for sight?

A

Optic nerve
CN 2

34
Q

What do the 3 layers of the eye consist of?

A

Outer layer = Sclera and cornea
Middle layer = Uvea (iris, ciliary body, choroid)
Inner layer - Retina

35
Q

What is the role of the iris?

A

To control the amount of light reaching the retina by adjusting the pupil size

36
Q

List the accessory structures of the eye.

A
  • Eyebrow
  • Eyelids
  • Eyelashes
  • Conjunctiva (this mucous membrane)
  • Lacrimal apparatus (tears)
37
Q

Explain how tears play an important immune role.

A

Contain IgA and lysozymes

38
Q

Describe the path tears take

A

Produced by the lacrimal gland.
Swept across the eye by blinking.
Drain into the lacrimal punctum into the nose

39
Q

Name the cranial nerve that controls tear secretion.

A

Trigeminal nerve
(CN 5)

40
Q

List THREE ways in which clear vision is achieved by the eyes.

A
  • Refraction of the light rays
  • Accommodation of the eyes
  • Changing the size of the pupils
41
Q

What is refraction?

A

The ‘bending’ of light rays. It occurs when light moved from one substance to another which has a different density.

42
Q

Name ONE eye component that refracts most light rays.

A

Cornea
(to a lesser extent, the lens)

43
Q

Describe in detail the difference between:

a. Greater refraction
b. Less refraction

A

a. Greater refraction
When an object is close, the ciliary muscle contracts. This reduces suspensory ligament tension and the lense becomes convex.

b. Less refraction
When an object is distant, the ciliary muscles relax, increasing the tension on the suspensory ligaments and flattening the lens.

44
Q

Explain why an individual may experience ‘double vision’.

A

If convergence is not complete, two images are sent to the brain leading to double vision.

45
Q

Name the location where the optic nerve crosses over in the brain.

A

Optic chiasma

46
Q

Explain why a pituitary tumour can cause ‘tunnel vision’.

A

The optic chiasma is located next to the pituitary gland which is why a pituitary tumour can cause tunnel vision

47
Q

Name one investigative tool that can be used to view the retina.

A

Ophthalmoscope

48
Q

Name the location where the optic nerve exits the eyeball.

A

Optic disc (blind spot)

49
Q

List TWO layers of the retina.

A

Pigmented layer
Photoreceptors layer

50
Q

Describe THREE differences between ‘rod cells’ and ‘cone cells’.

A

Rod cells:
120 million
Allow to see in dim light
Provide black, white and grey scale

Cone cells:
6 million
Produce colour vision
Blue, Red and Green cone cells.

51
Q

Describe TWO features of the ‘fovea centralis’.

A

(Small depression in the centrre of the macula lutea)

  • Only contains cone cells
  • Area of highest visual acuity
52
Q

State where you would expect to find ‘rod cells’ in the retina.

A

Periphery of the retina

53
Q

What are photo pigments and describe how light affects them.

A

Photo-pigments are transmembrane proteins within the discs of both rod and cone cells.

They change shape when light hits them, initiating action potential.

Once activated, they must regenerate which requires Vitamin A

54
Q

State where Vitamin A is stored in the eye.

A

The pigmented layer of the retina

55
Q

Name the protein bound to Vitamin A in the eye.

A

Opsin

56
Q

List two food sources of:

a. Pre-formed vitamin A
b. Carotenoids

A

a. Pre-formed vitamin A
Live
Eggs

b. Carotenoids (precursors for Vit A)
Carrots
Sweet potato
Leafy greens
Squash
Mango

57
Q

Describe how the eyes adjust in the following situations:

a. Moving from dark to light sensitivity
b. Moving from light to dark sensitivity

A

a. Moving from dark to light sensitivity
Adapt quickly by decreasing sensitivity

b. Moving from light to dark sensitivity
Adapt much slower in the increase in sensitivity.
Rod cells take longer to regenerate.

58
Q

What is Blepharitis and who does it commonly affect?

A

Inflammation of the eye margin.
More common in adults

59
Q

What are the characteristic signs and symptoms of blepharitis?

A

Red eyelid margins
Sore, gritty eyes
Scales and flakes on the eye margin.
Eyelids may stick together in the mornings.

60
Q

Why are Omega-3 fatty acids good for some eye pathologies?

A

Improves tear quality (boosting immune function)

61
Q

What is a stye and its common cause?

A

Inflammation of the sebaceous glands of the eye lid.
Usually bacterial infection.

62
Q

What are the characteristic signs and symptoms of styes?

A

Red, swollen and/or painful infection of sebaceous glands of the eyelid.

63
Q

List ONE endocrine pathology that increases the risk of styes.

A

Diabetes melititus

64
Q

What is conjunctivitis and it’s common causes?

A

A highly contagious inflammation of the conjunctiva.
Caused by virus, bacteria or allergies.

65
Q

What are the characteristic signs and symptoms of conjunctivitis?

A

Red irritated/uncomfortable eye
Watery/purulent discharge

66
Q

With regards to conjunctivitis, describe the key difference in discharge from the eye due to a:

a. Virus
b. Bacteria
c. Allergy

A

a. Virus - watery
b. Bacteria - purulent
c. Allergy - watery

67
Q

What is the term used to describe inflammation of the uvea?

A

Uveitis

68
Q
  1. List ONE viral and one autoimmune disease cause of uveitis.
A

Viral - herpes
autoimmune - Ankylosing spondylitis

69
Q

Describe THREE characteristic signs and/or symptoms of uveitis.

A

Progressive unilateral red eye with pain, blurred vision, and photophobia.

70
Q

Explain why a corneal ulcer is a medical emergency.

A

Possible loss of sight

71
Q

What is strabismus and list ONE pathology that can cause it.

A

Misalignment of the eyes.

Stroke or brain tumour causing damage to the nerves supplying extra-ocular muscles

72
Q

Describe the difference between a healthy lens and a lens affected by cataracts.

A

A healthy lens is clears
Cataract lens is opaque

73
Q

List TWO causes (not age) of cataracts.

A

Diabetes mellitus
Smoking
Steroids

74
Q

Define age-related macular degeneration (AMD).

A

Describes the aging changes that occur in the central areas of the retina.

75
Q

List TWO causes (not age) of AMD.

A

Smoking
Cardiovascular disease
Family history

76
Q

Describe how vision is affected in AMD.

A

Reduced visual acuity
Particular difficulty with near vision
Gradual and progressive loss of central vision

77
Q

List TWO diagnostic methods used to diagnose AMD.

A

Amsler grid
Ophthalmoscope

78
Q

Identify the following pathology:
‘Floaters in vision, flashing lights, curtains descending over vision’.

Explain how the pathology develops

A

Retinal detachment.

Separation of the neurosensory layer of the retina from the pigmented epithelium.

79
Q

Describe specifically how glaucoma produces eye symptoms.

A

Glaucoma is the increased intraocular pressure caused by inadequate drainage.

Causes compression of the retina and optic nerve.

80
Q

List ONE lifestyle factor that may cause glaucoma.

A

Smoking

81
Q

List TWO signs and / or symptoms associated with:

a. Mild acute glaucoma
b. Severe acute glaucoma

A

a. Mild acute glaucoma
Pain in the eyes
Haloes around light

b. Severe acute glaucoma
Rapid deterioration of vision
Intense eye pain
Redness and watering of the eye
Sensitivity to light
Nausea & vomiting

82
Q

List TWO signs/symptoms of late chronic glaucoma.

A

Loss of peripheral vision
Blurred objects directly in front of the person
Loss of night vision

Biomedicine II CNM (2024) (8 decks)

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