nervous system Flashcards

1
Q

21: 3 subdivisions of somatosensory system

A
cutaneous sensations (skin) 
visceral (internal organs) 
proprioception (limbs in body)
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2
Q

21: action potential initiation

A

receptor potential exceeds threshold

nerve fibre fires a.p.

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3
Q

21: sensory transduction - steps

A
  1. receptor potentila
  2. integration at trigger zone
  3. a.p
  4. neurotransmitter release
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4
Q

21: cutaneous skin receptors

A
superficial 
merkels disk 
epidermal dermal border 
free nerve ending 
messiers corpuscle 
deep
pacinian corpuscle 
ruffians corpuscle
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5
Q

21: receptive field

A

area over which stimulus activates receptor

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6
Q

21: receptive field - eye

A

retina

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7
Q

21: receptor adaptation - rapidly adapting receptor vs slowly adapting receptor

A

rapid = neuron stop firing a.p even though stimulus is maintained
slow - nerve continues firing a.p throughout stimulus

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8
Q

21: rapid adaptation of pacinian corpuscle when capsule is present vs when its removed

A

present - rapid adaptation of receptor potential

removed - less adaptation of receptor potential, adaptation eliminated

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9
Q

21: temperature receptors - warm vs cold

A

warm - C fibres

cold - Asigma

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10
Q

21: 2 pathways that transmit cutaneous signals to the brain

A

dorsal column pathway (DC)

spinothalamic tract pathway (STT)

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11
Q

21: where are cell bodies of primary sensory nerve fibres found

A

dorsal root ganglion

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12
Q

21: where do fibres enter

A

spinal cord at dorsal root

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13
Q

21: dorsal column pathway

A
  • first synapse - dorsal column nuclei in medulla
  • pathway crosses over (left to right cortex and right to left cortex)
  • feedback to motor systems
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14
Q

21: forsal column pathway - carries information about

A

stimuli moving over skin

recognition of objects

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15
Q

21: connections of the spinothalamic tract (STT)

A

spinothalamic pathway crosses over with spinal cord and travels up spinal cord in thalamus

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16
Q

21: what does the STT carry information about

A

coarse touch
temperature
nociception painful stimuli

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17
Q

21: body region with largest area of representation on somatosensory cortex

A

hands and face

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18
Q

21: muscle spindles respond to

A

muscle stretch

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19
Q

21: golgi tendons respond to

A

muscle tension

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20
Q

22: muscle coordination - flexion

A

contract flexors and relax extensors

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21
Q

22: muscle coordination - extension

A

contract extensors and relax flexors

22
Q

22: muscle coordination - synergists

A

muscles that pull in the same direction

23
Q

22: muscle coordination - antagonists

A

muscles that pull In the opposite direction

24
Q

22: muscle coordination - e.g of synergists sand anatagonists

A

synergists - brachialis + biceps

antagonists - biceps and triceps

25
Q

22: single motoneuron can innervate several muscle fibres - large motor unit

A
  • each motorneuron innervates many muscle fibres

- strong force

26
Q

22: single motoneuron can innervate several muscle fibres - small motor unit

A
  • each motoneuron innervating a few fibres
  • fine control
  • lots in finger muscles
27
Q

22: 3 sources of input of motor neurones

A

upper motor neurones (command + control, voluntary movement)
interneurones in spinal cord (excitatory + inhibitory)
receptors - muscle spindles and golgi tendons

28
Q

22: response of muscle spindle to stretch - what happens when the muscle contracts

A

spindle is unloaded so it ceases to fire

29
Q

22: muscle spindles + golgi tendon - innervated by (supply with nerves)

A

ms - 1a afferents that go to spinal cord

gt - 1b nerve afferents that go to spinal cord

30
Q

22: muscle spindles - gamma motor neurones

A

contract intrafusal fibres

31
Q

22: 3 types of movement

A
reflex 
- involuntary
- initiated by external stimuli  
voluntary 
- conscious 
- may be learned 
rhythmic 
- initiated + terminated by conscious control
32
Q

22: reflex movement - origin

A

spinal

cranial

33
Q

22: afferent and efferent pathway in a knee jerk reflex

A

afferent - a.p through sensory neurones
efferent - somatic motor neuron
efferent 2 - interneuron inhibiting somatic motor neuron

34
Q

22: voluntary control of movement - what do pathways from the brain control

A

motor neurons in spinal cord

35
Q

22: voluntary control of movement - Brain areas involved in voluntary movement

A

cerebral cortex - plan, coordinate and initiate
basal ganglia - plan and select movements
cerebellum - fine tunes movement

36
Q

23: sound

A

longitudinal pressure wave travelling through air or other medium

37
Q

23: what is sound defined by

A

frequency (Hertz)

amplitude (deciBels)

38
Q

23: the outer ear

A
  • pinna - sound gathered by orientation
  • externalisation of sounds - sound perceived inside head
  • localisation of sounds in vertical plane - sound waves interfere on surface of pinna
39
Q

23: middle ear - consequence of unequal pressure across tympanic membrane

A

impaired hearing

40
Q

23: why do we need the middle ear

A
  • without it there would be a poor transfer of energy from air to cochlear fluid
  • impedance transformer
41
Q

23: function of middle ear

A
  • overcomes air - fluid mismatch

- force on tympanic membrane = increases pressure

42
Q

23: small processes at the end of inner hair cells of human ears

A
  • process called stereocilia

- bend in response to pressure changes

43
Q

23: what happens when sound enters cochlea

A
  • basilar membrane vibrates
  • waves travelling up
  • displacement of basilar membrane excites hair cells
44
Q

23: cochlea - low frequencies vs high

A

low - maximal displacement at apex of cochlea

high - maximal displacement at the base

45
Q

23: stereo cilia bending towards longest vs shortest

A

entry of k+ - no entry

depolarisation, ca2+ entry - hyperpolaristaion

46
Q

23: activation of hair cells - movement of basilar membrane + interaction with tectorial membrane

A

causes bending of stereo cilia of inner + outer cells

47
Q

23: activation of hair cells - inner hair cells only

A

release neurotransmitter

activate cochlear nerve fibres associated with hair cell

48
Q

23: outer hair cells

A
  • shorten + lengthen

- inject energy and amplify basilar membrane

49
Q

23: outer hair cells - what is it driven by

A

motor protein in OHC membrane - prestin

50
Q

23: outer hair cells - elongation and shortening of outer hair cells results in

A

increased displacement of basilar membrane which enhances hearing sensitivity nf frequency selectivity