Sense Organs Flashcards

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1
Q

Which parts of the ear make up the outer ear

A

Pinna and auditory canal

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2
Q

What is the function of the pinna

A

Directs sound waves to the auditory canal

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3
Q

What is the function of the auditory canal

A

Transmits sound from pinna to the tympanic membrane

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4
Q

What are the parts of the middle ear

A

Tympanic membrane
Ear ossicles
Oval window
Round window
Eustachian tube

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5
Q

What is the tympanic membrane and what is its function

A

Tympanic membrane: a thin membrane that covers the opening between the auditory canal and the middle ear
Function:convert sound waves to vibrations that are transmitted to ear ossicles

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6
Q

What do the ear ossicles consist of and what are their function

A

Consists of anvil, hammer and stirrup
Function: transmit vibration in middle ear to oval window
Magnify the vibration (to accommodate for the fluid in the inner ear because sound in fluid becomes muffled/less clear)

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7
Q

What is the oval window and what is its function

A

Oval window: a thin membrane connecting middle ear to inner ear
Function: transmits vibration to inner ear

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8
Q

What is the Eustachian tube and what is its function

A

Eustachian tube: tube connecting the middle ear to the throat
Function: allows pressure in the middle ear to be equal to the atmospheric pressure so that pressure is the same on both sides of the tympanic membrane

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9
Q

What is the structure of the inner ear

A

Consists of bony labyrinth and membranous labyrinth
Bony labyrinth is system of canals and cavities in the skull
Bony labyrinth filled with perilymph
Membranous labyrinth is a system of membranous tubes and sacs found floating in the perilymph
Membranous labyrinth has the same shape as the bony labyrinth
Membranous labyrinth filled with endolymph
Bony labyrinth and membranous labyrinth filled divided in two sections: 1. Vestibular apparatus - for balance
2. Cochlea - for hearing

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10
Q

What is the vestibular apparatus comprised of and what is each part responsible for

A

Three semi-circular canals - direction and speed
Utriculus - have maculae which detect gravity
Sacculus - have maculae which detect gravity

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11
Q

What is the role of the utriculus and sacculus

A

Utriculus and sacculus contain maculae
Each macula has sensory cells with fine hairs embedded in a layer of jelly
Small crystals of calcium carbonate on the jelly called otoliths
Depending on position of head the weight of the otoliths will pull on different hairs
Interpreted by brain to tell us if we’re upright or not

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12
Q

What is the structure of the semi-circular canals

A

Three semi-circular canals positions at right angles to each other
Ampulla at base of each semi-circular canal
Ampullae contain sensory crista

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13
Q

What the function of the semi-circular canals

A

Responsible for detecting movement in head (direction and speed)
Endolymph fluid fills semi-circular canals and stimulates sensory crista as head moves
Fluid will flow in one of the semi-circular canals more than the others depending on the direction of movement of the head
This information is fed to the cerebellum help maintain balance

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14
Q

What is the cochlea

A

A Long, coiled, structure which is divided along its length into three compartments

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15
Q

What is the structure of the cochlea

A

3 compartments
Upper compartment: has perilymph and connects to oval window
Middle compartment: has endolymph and organ of corti
Lower compartment: has perilymph and connected to round window
Organ of corti has many sensory hairs which connected to the auditory nerve

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16
Q

How does the cochlea work

A

Vibration is transmitted from the stapes to the oval window then into the endolymph
Vibrations tug at the hair cells of the organ of corti
Sensory hair cells send impulse to the auditory nerve to the cerebrum (temporal lobe) which interprets the sound
Vibrations continue through perilymph of the lower chamber to the round window where they are lost to the air of the middle ear

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17
Q

What’s the function of the round window

A

Releases inner ear pressure and basilar membrane vibration

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18
Q

What is the difference between conductive deafness and neural deafness

A

When one of the mechanisms conducting the sound waves/vibrations fails e.g: tympanic membrane damaged
Neural deafness: problems of the inner ear (organ of corti) or the auditory nerve or temporal lobe of brain

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19
Q

What are the possible causes of deafness

A

Accumulation of wax against tympanic membrane
Long term exposure to loud noise
Hereditary
Infections e.g: meningitis

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20
Q

What are possible treatments of deafness

A

Hearing aids
Cochlear transplants

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21
Q

How does a hearing aid work

A

Amplifies sound
Patient must have some hearing

22
Q

What is a cochlear transplant

A

An electronic device that is implanted surgically to enable hearing in people with serious or profound deafness, where the inner ear is damaged

23
Q

How do cochlear transplants work

A

Device has 2 parts:
External part has a microphone, speech processor and transmitter which allow for sound in the environment to be detected, converted to an electrical signal and sent to the internal part of the cochlear transplant
Internal part: receives the transmitted electrical signal, converts it to an electrical impulse which stimulates the auditory nerve to conduct them to the brain

24
Q

How do middle ear infections happen so easily

A

Middle ear has Eustachian tube which is connected to throat
Throat infections can easily connect to the middle ear

25
Q

How does a middle ear infection happen

A

Eustachian tube blocks and pressure builds up in the middle ear = causes tympanic membrane to to bulge = pain in middle ear

26
Q

How can middle ear infection be treated

A

Anti-biotics

27
Q

What is the difference between a sense organ and a receptor

A

SO: comprised of many tissues and one of them is receptors
R: the actual issue/cells responsible for receiving stimulus

28
Q

How are our eyes positioned and structured (from outside pov)

A

Eyes positioned in skull sockets to protect from injury
6 eye muscles hold eye in place and help with side to side and up and down movement
Eyelids and eyelashes help protect eye from foreign objects
Tear gland secretes antiseptic tears to protect conjunctiva from infection and dehydration

29
Q

What is the name of the strong, white inelastic layer in the eye and what is its function

A

Sclera
Protects eye
Helps eye keep its shape
Place of attachment for muscles
Cornea forms in front of it

30
Q

What is the name of the transparent layer of the eye and what is its function

A

Cornea
Allow light to enter the eye
Helps bend/refract light rays to focus the image

31
Q

What is the choroid

A

The layer that has pigment which prevents internal reflection of light

32
Q

What is the ciliary body and what is its function

A

Part of the eye comprised of ciliary muscles and suspensory ligaments
Changes the shape of the lens to focus the image

33
Q

What is the name of the pigmented, muscular layer with a hole in the middle and what is its function

A

Iris - controls the amount of light entering the eye (hole in the middle = pupil)

34
Q

what is the lens and what is its function

A

Lens - a rubbery, elastic, transparent Biconcave structure
It can change shape to focus the image on the retina

35
Q

How does the retina work

A

Has photoreceptors: rods and cones
Rods = sensitive to low light, only allow black and white vision
Cones = sensitive to bright light, allow for colour
Cones located in the yellow spot (fovea) the part of the retina that is the centre of our focus

36
Q

What is the function of the optic nerve

A

Transmits impulses from eye to cerebrum (occipital lobe)

37
Q

Where is the blind spot

A

Where the optic nerve leaves the retina; no photoreceptors here

38
Q

What is the vitreous humour and What is its function

A

Clear jelly-like substance
Maintains the shape of the eye
Hold retina against the choroid

39
Q

How does sensation of light occur

A

Light is refracted as it passes cornea, lens and vitreous humour
The refraction forms an image which is centred at the fovea (yellow spot) of the retina
The image is small and inverted
Many photoreceptors record small parts of the images and send the information to the optic nerve
Optic nerve transmits the information and the brain pieces the information together to form a picture

40
Q

What is accommodation

A

The process whereby the eye adapts to focus on objects closer than 6m

41
Q

How does the eye work when focused on images further than 6m away

A

The circular ciliary muscles are relaxed
Natural elasticity of eyeball pull ciliary body away from lens on all sides
Sensory ligaments pulled taught
This flattens the lens and its becomes less convex (less confer = less bending of light)
Less refraction occurs
Image is focused on retina

42
Q

How does the eye work when it focuses on an image closer than 6m away

A

The circular ciliary muscles contract
Ciliary body moves in towards the lens (because the diameter of the circle created by the ciliary muscle decreases)
Tension on the suspensory ligaments is released
The lens has a more convex shape (more convex = bends light more)
More refraction of light occurs
Image is focused on retina

43
Q

What is binocular vision

A

Our two eyes overlap so objects in front of us are observed by both eyes simultaneously
This helps to judge distance more accurately
Field of binoculars vision = 140 degrees

44
Q

What is pupillary reflex

A

Reflex action that controls the amount of light that enters the eye by changing the size of the pupil via the circular muscles and radial muscles in the iris

45
Q

How does the pupillary reflex action work in bright light

A

Radial muscles relax
Circular muscles contract
Pupil constricts
Less light enters the eye

46
Q

How does the pupillary reflex work in dim light

A

Radial muscles contract
Circular muscles relax
Pupil dilates
More light enters the eye

47
Q

Why is the iris pigmented

A

So that light only enters through the pupil

48
Q

What is myopia, what causes it, and how can it be fixed

A

When distant object are out of focus
Caused by elongated eyeball or abnormal curvature of the cornea
Fixed with concave lenses or laser surgery

49
Q

What is hypermetropia, what causes it and how can it be fixed

A

Close up objects are out of focus
Caused by shortened eyeball or an abnormally flat cornea
In some older people it can be becuase the eyeball has lost elasticity and does not return to its round shape when tension in the suspensory ligaments is released
Fixed with convex lenses or laser surgery

50
Q

What is astigmatism and how can it be fixed

A

Visual defect caused by an irregularly shaped cornea or lens, causes blurred images at all distances
Fixed with prescription lenses or surgery

51
Q

What are cataracts and how can they be fixed

A

Cataract = clouding of the lens that happens gradually leading to gradual loss of vision
Fixed with surgery where lens is replaced with synthetic lens