WEEK 6: 6.2 Special Senses Flashcards

1
Q

What is the labelled lines principle?

A

The specific pathway that transmits information about a specific modality is a ‘labelled line’. Stimulation of a labelled line only produces a sensation of its modality, no matter what type of energy produces the action potentials

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2
Q

What are the steps involved in vision: eye

A
  1. Light waves pass through the cornea (a clear protective outer layer)
  2. light waves pass through the pupil (a small opening in the eye surrounded by the iris which regulates the amount of light entering the eye.
  3. light waves pass through the lens
  4. light waves as projected onto the retina, which contains all of the receptor cells
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3
Q

What receptors do light activate?

A

Photoreceptors, located within the retina of the eye

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4
Q

What are two different types of photo receptors

A
  • Rods (monochromatic & low visual acuity)
  • Cones (mediate colour vision, high visual acuity)
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5
Q

What happens once light information is processed within the retina photoreceptors?

A

this visual info is passed onto bipolar nerve cells -> ganglion cells (their axons form optic nerve)

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6
Q

What is the centre of the retina called

A

Macula, in which the fovea is the pit inside the macula that contains only cones

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7
Q

What is the ratio of rods to cones in the periphery of the retina?

A

Higher ratio of rods to cones

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8
Q

What is the blindspot called in the retina?

A

Optic disc

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9
Q

Image on the retina is ___ and ___

A

inverted and reversed

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10
Q

What is the optic nerve formed from?

A

axons and ganglion cells

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11
Q

optic nerve joins with an opposite optic nerve to form the

A

optic chiasm

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12
Q

What occurs in the optic chiasm

A

The partial crossing of optic nerve fibres, in which medial nasal retinal fibres cross whilst lateral temporal retinal fibres do not crosss

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13
Q

Axons from the optic tract terminate in the?

A

thalamus (in a region called lateral geniculate nucleus)

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14
Q

as the axons leave the thalamus, they form optic ___

A

radiations

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15
Q

After forming optic radiations, the axons then terminate in the

A

primary visual cortex

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16
Q

Where is the primary visual cortex located?

A

above the calcarine sulcus in the occipital lobe

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17
Q

What are the two different streams in which further processing of information happens in visual association areas?

A
  • What stream: towards temporal cortex that recognises what an object is
    -Where stream: Towards the parietal cortex that allows for recognition of where an object is
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18
Q

What 3 parts can the ear be divided into?

A

The external ear, middle ear and inner ear

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19
Q

What is the external ear’s function?

A

Sound collection , localising sound

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20
Q

What is the middle ear’s function?

A

impedance matching between outer ear (air) and inner ear (liquid)

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21
Q

What is the inner ear’s function?

A

signals are analysed and transduced

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22
Q

What are the sensory receptors in the inner ear essential for hearing?

A

hair cells

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23
Q

What is the function of hair cells?

A

to convert sound vibrations into electrical signals

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24
Q

Describe the steps in which hair cells work?

A
  1. sound enters the ear, travels through the ear canal, hits the eardrum and causes it to vibrate
  2. vibrations are transmitted through ossicles, middle ear bones, to the cochlea in the inner ear
  3. inside the cochlea, sound vibrations create waves in fluid-filled chambers
  4. these waves move to the basilar membrane, causing hair cells sitting on it to bend
  5. when hair cells bend, they generate electrical signals sent to the brain via the auditory nerve
  6. the brain interprets these signals as sound
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25
What are the two types of hair cells
Inner hair cell (detects sound and sends it to the brain) Outer hair cell (amplifies sound vibrations to make inner hair cells more sensitive
26
What pathway does the information transmitted by hair cell receptors follow?
1. bipolar cells in spiral ganglion take information from hair cell receptors to the vestibulocochlear nerve 2. this info travels to the cochlear nuclei- medulla oblongata 3. this info then travels to the inferior colliculi (metencephalon) 4. this info then travels to the medial geniculate nuclei (mesencephalon) 5. finally sound info is transmitted to the primary auditory cortex (telencephalon)
27
what does monoaural information refer to?
info from one ear = moved to the other side of the brain
28
what does binaural info refer to?
info about the differences between sounds at two ears
29
The vestibular labyrinth is related to?
Balance
30
What are the main structures in the vestibular system>
three semicircular canals and two otolith organs (the utricle and saccule)
31
the vestibular nuclei in the brainstem have connections to ?
motor centers for control of eye movement, head movement, posture, limb movement and upright position as well as the thalamus and cortex for the conscious perception of where we are in space
32
What do the anterior, posterior and lateral semicircular canals detect?
rotation of the head
33
What do the otolith organs detect?
Linear movements and the position of your head relative to gravity
34
In what steps does information regarding balance move through?
Hair cells -> vestibular ganglion cells -> vestibular nuceli -> cerebellum (info related to control of movement)
35
What is vertigo?
the feeling one is moving with respect to the environment , or the environment is moving when it is stationary
36
What is the broca area
- Language production, speaking words, and comprehension - Posterior inferior frontal gyrus
37
What is Wernicke area
- Comprehension of written and spoken language - Posterior superior temporal gyrus
38
What is the secondary auditory cortex
Where hearing is processed
39
What does the arcuate fasiculus do?
Connect Wernicke's and Broca's areas
40
What is broca's aphasia
Know what to say but you can't
41
What is Wernicke's aphasia
Fluent speech but words lack meaning - inability to comprehend spoken words
42
Briefly list the steps in which information is transmitter when hearing and comprehending words
1. Hearing occurs when sound enters the inner ear 2. transferred this info to Area 41 (gyri transversales, temporal lobe) 3. transfer such info to Wernicke's area for sensory matching 4. Hear and comprehend words
43
Briefly list the steps in which information is transmitted when speaking
1. Wernicke's area is accessed for word storage 2. Wernicke's area transmits info to Broca's area for motor program of speech 3. Broca's area sends speech info to the motor cortex for the purpose of motor execution 4. The motor cortex sends speech info to the cranial nerves Speech occurs
44
Once speech/language information is processed in the wernicke brocas and premotor/motor cortices, this information comes out in the
Corticobulbar tract, motor nuclei of cranial nerves and cranial nerves
45
For speech, the cranial nerves innervate the
muscles of face, tongue, pharynx and suprahyoid muscles
46
the brain and cranial nerves work together to control:
phonation (sound production) articulation (forming speech sounds)
47
What cranial nerves are involved in speech?
1. CN X (vagus nerve) 2. Respiration 3. CN IX (glossopharyngeal) and X (vagus) 4. CN XII (hypoglossal) 5. Facial CN VII
48
What is the pathway from the motor cortex to the cranial nerves?
1. starts in the motor cortex 2. travels via the corticobulbar tract 3. ends at the motor nuclei of cranial nerves X, XI, XII and VII
49
Speech isn't just about motor signals, it involves
Feedback from sensory nerves to fine-tune and adjust speech
50
The vagus nerve provides sensory feedback from the ____ & ___ to control speech accruately
larynx and vocal cords
51
What two branches does the superior laryngeal nerve have?
an internal branch - sensory input an external branch- motor control to cricothyroid muscle
52
What are odourants captured on?
the olfactory epithelium
53
what are two types of epithelium present in the nasal cavity?
respiratory and olfactory epithelium
54
what are olfactory receptor cells?
they are in the olfactory epithelium, and are the site of transduction, they transform chemicals into the sense of smell
55
How do olfactory receptor cells work?
odourants in the air dissolve in mucus, which holds odourants in place so they come in contact with olfactory receptors, this stimulation generates receptor potential
56
What type of neuron are olfactory receptor neurons?
bipolar neurons
57
The thin unmyelinated axons of the olfactory receptor cells form the?
Olfactory nerve
58
Where do the olfactory nerves first synapse?
The olfactory bulb
59
What are glomeruli
synaptic hubs where the olfactory axons meet and synapse with the dendrites of neurons rising in the olfactory bulb
60
So in what order does olfactory info travel?
olfactory bulb -> olfactory tract -> mostly terminates in the primary olfacotry cortex -> other locations for further processing (amygdala, hippocampus, orbitofrontal cortex)
61
What are the 5 basic tastes?
sweet, sour, umami, bitter, salty
62
62
What are papillae
numerous bumbs on the upper surface of the tongue, which contain numerous taste buds that contain taste receptor cells
63
T or F: Taste receptor cells are neurons
F: they aren't neurons, they form synapses with endings of gustatory afferents near the bottom of the taste bud
64
Briefly describe the steps in which gustatory transduction occurs
1. tastant enters the mouth & molecules combine with saliva & bind to taste receptors 2. depolarisation causes calcium channels to open, and an influx of ca2+ ions trigger release of neurotransmitter molecules 3. neurotransmitter excites post synaptic sensory axon to fire action potential
65
T or F: Most of the tongue is sensitive to all basic tastes
T
66
How is this gustatory info transmitted to the brain?
- 3 cranial nerves innervate different regions of the tongue and throat - info is passed onto the medulla (gustatory nucleus, thalamus and finally the cerebral cortex (gustatory cortex)
67
Where is the primary taste cortex located?
in the parietal lobe and insula
68
Flavour is a function of?
Taste and smell - retronasal and orthonasal olfaction