ANS, visual, hearing pathways Flashcards

1
Q

outer layer of eye

A

cornea - transparent, a-vascular, refraction

sclera - white opaque area, muscles insert for eye movement

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2
Q

middle, vascular layer of eye

A

choroid- vascular, nourishes cornea, retina
iris- pigmented, vascular, muscles which change diamater of pupil
ciliary body- controls shape of lens via suspensory ligaments
lens- biconvex, A-vascular

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3
Q

inner layer of eye

A

retina (extension of diencephalon)

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4
Q

features of non-neuronal layer of retina

A

pigmented epithelium, sitting against choroid of eye.

absorbs light

maintains the metabolic activity of photoreceptors

provides cap. to the photoreceptors

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5
Q

features of neuronal layer of retina

A

photoreceptors

1st order bipolar neurones

2nd order ganglion nuerones

optic disk –> point where axons of ganglion neurones leave the retina to become the optic nerve

interneurones: horizontal and amacrine interneurones

photochemical reactions occur here

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6
Q

features of rods

A

20 x more common, sensitive to light, vision in dim-light, high level of convergence
found everywhere

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7
Q

features of cones

A

colour vision, high visual acuity, lower levels of convergence , at macula= one cone for every ganglion cell
found in macula/ fovea/ not in periphery

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8
Q

the visual pathway is a 3 neurone chain. the optic nerves will combine to cross at …

A

the optic chiasm: hemi-decusation (nasal fibres will cross, temporal will not)

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9
Q

location of the visual cortex

A

above and below the calcarine sulcus, extending to the occipital pole

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10
Q

our eyes are binocular. what does this mean

A

both of our eyes see the same thing

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11
Q

what is fixation point

A

point of visual acuity corresponding to the fovea. it where all quadrants of visual field meet

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12
Q

define scotoma

A

localised patch of blindness

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13
Q

define anopia and give examples of 2 types

A

the loss of one or more quadrants of the visual field

e. g. hemianopia= one HALF of the visual field is lost (both of upper and lower on that half are lost)
e. g. quadrantanopia= one QUADRANT of the visual field is lost only

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14
Q

define homonymous

A

visual field losses are on same side for both eyes

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15
Q

define heteronymous

A

visual field losses are on different sides for both eyes

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16
Q

3 examples of visual defects

A

monocular blindness (completely blind in ONE eye)

bi-temporal hemianopia (outer half BOTH right and left visual field is missing)

homonymous hemianopia (visual field loss on same side of both eyes)

17
Q

which region of the external ear is bony/cartilaginous

A

lateral 1/3= cartilaginous

medial 2/3= bony

18
Q

tympanic membrane may be called the eardrum. what is its function

A

to separate the external and middle ear.

–> it is part of middle ear

19
Q

middle ear is high risk space why?

A
  1. eustachian tube connects it to naso-pharynx= prone to infection
  2. connected to mastoid air cells= infection spread to middle cranial fossa
  3. inferior is the IJV= risk of thrombosis
  4. anterior is the internal carotid artery= risk of pulsatile tinnitus
  5. transversed by facial nerve and canal= infection spread to facial muscles
20
Q

3 features of the auditory pathway

A

polysynpatic (many neurones/ synpases)

tonotopically organised

bilateral (recieve sound from both ears)

21
Q

auditory centres in brainstem are…

A

cochlear nuclei
SUPERIOR olivary nuclei
inferior colliculus
MEDIAL geniculate nucleus

22
Q

cell bodies of the cochlear nerve (CN8) are in the

A

spiral ganglion. will travel into the dorsal/ventral cochlear nuclei

23
Q

where are low and high frequency sound recieved in cochlear and projected in the heschl’s gyrus

A

base= high
apex=low

low= antero-lateral part of heschl's gyrus
high= postero-medial part of heschl's gyrus
24
Q

secondary auditory areas

A

brocas- anterior of frontal, motor production of speech

wernickes - posterior of temporal, understanding of speech

25
Q

define anxiety

A

a FEELING of worry, nervousness, unease –> typically about an imminent even or something with an uncertain outcome BUT it has physical effects (racing heart, heaving breathing, sweating, dry mouth)

26
Q

function of autonomic NS

A

to monitor the VISCERAL ACTIVITY to maintain homeostasis

27
Q

distinct feature of somatic and autonomic MOTOR efferent fibres

A

in ANS, the visceral motor efferent fibres leave the spinal cord via the LATERAL GREY HORN which is present only within the segmental spinal nerves T1-L2 and S2-4

28
Q

in the ANS there is a 2 neurone chain- not seen in somatic. what are the names of neurones and where are they located

A

pre-ganglionic neurone- somewhere in CNS

post-ganglionic nuerone going to target organ- somewhere in the PNS

NB. synapse at the ‘autonomic ganglion’

29
Q

outflow of symp and para are..

A

sympathetic= thoracolumbar outflow, T1-L2

para= cranio-sacral outflow, S2-S4 (occulomotor, facial, glossopharyngeal, vagus)

30
Q

which neurotransmitter is released by symp/para fibres

A

para=acetylcholine released by BOTH neurones. localised effects (1:1 of pre and post neurones)

symp= acetylcholine by pre and then noradrenaline by post-ganglion neurone BUT sweat glands post-ganglionic neurones release a different neurotransmitter