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MD4001 Physiology > Ascending Pathways > Flashcards

Ascending Pathways Flashcards

1
Q

How many neurons are involved in getting sensation to the brain?

A

3

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2
Q

What are the slowly adapting receptors?

A
  • Golgi tendon organs (JPS)
  • Ruffini endings (skin stretch, pressure, JPS)
  • Merkel endings (pressure, low frq vibration)
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3
Q

What is the difference between rapidly and slowly adapting fibres?

A

Rapidly adapting, or phasic, receptors respond maximally but briefly to stimuli; their response decreases if the stimulus is maintained. Conversely, slowly adapting, or tonic, receptors keep firing as long as the stimulus is present

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4
Q

WHat is a feature of nociceptors?

A

Free nerve endings (carry pain)

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5
Q

What senses do Ruffini endings detect?

A

Skin stretch, pressure, JPS

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6
Q

What do Pacinian corpuscles detect?

A

Vibration, JPS

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7
Q

What do muscle spindles detect?

A

Muscle length, proprioception

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8
Q

What do merkel endings detect?

A

Pressure, low frq vibration

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9
Q

What do meissner corpuscles detect?

A

Light touch

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10
Q

What do hair follicle receptors detect?

A

Touch

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11
Q

What do golgi tendon organs detect?

A

Joint position sense (JPS)

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12
Q

How do generator potentials differ to action potentials?

A
  • Slower

- Increased permeability to all ions (not just Na+,K+)

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13
Q

What are the 4 different types of primary afferent axons?

A
  • Aalpha
  • Abeta
  • Adelta
  • C
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14
Q

What senses are carried by Aalpha axons?

A

Proprioceptors of skeleral muscle

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15
Q

What senses are carried by Abeta axons?

A

Mechanoreceptors of skin

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16
Q

What senses are carried by Adelta axons?

A
  • Pain

- Temperature

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17
Q

What senses are carried by C axons?

A
  • Temperature
  • Pain
  • Itch
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18
Q

What happens to the density of dendrites as you move closer to the cell body?

A

Higher density thus higher density of input

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19
Q

What does lateral inhibition allow for?

A

Sharpens discrimination between two points excenuates location of stimulus

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20
Q

Where can lateral inhibition take place other than the skin?

A

Visual pathway

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21
Q

Dermatomes

A

LEARN

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22
Q

Where is the 1st neuron cell body located on the sensory pathway?

A

Dorsal root ganglion

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23
Q

What fibres does the ventral root carry?

A

Motor

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24
Q

What are the 2 pathways to the cerebral cortex for conscious sensation?

A
  • Dorsal column

- Anterolateral column

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25
Q

Where does the dorsal column pathway cross over?

A

Medulla

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26
Q

What do the anterolateral pathways carry?

A

Pain, temperature, itch

27
Q

Where do the anterolateral pathways cross over?

A

Near level where they come into spinal cord

28
Q

WHat can the dorsal column pathway also be known as?

A

Medial lemniscal pathway

29
Q

What senses are carried through the dorsal column / medial lemniscal pathway?

A

Vibration and canscious position sense, two point discrimination / fine touch

30
Q

Describe the dorsal column / medial lemniscal pathway route?

A
  • 1st neuron - DRG, spinal cord ascends on same side to medulla
  • 2nd neuron - medulla, axon crosses and ascends to thalamus
  • 3rd neuron - in thalamus ascends to cerebral cortex (postcentral gyrus)
31
Q

Where are first neuron leg fibres located in the spinal cord?

A

Gracile tract

32
Q

Where is the second neuron from the leg found in the spinal cord?

A

Gracile nucleus

33
Q

Where are the second neuron fibres from the leg found?

A

Medial lemniscus (vent then dorsal)

34
Q

Where are the first neuron arm fibres found in the spinal cord?

A

Cuneate tract

35
Q

Where are the second neuron arm fibres and neuron found?

A
  • In the cuneate nucleus (crosses midline)

- Continues in medial lemniscus (rotates as ascends)

36
Q

What is fine tactile and proprioceptive information used for?

A
  • To determine the shape of an object (without sight) (proprioception from finger joints + fine discriminating touch)
  • To determine the texture of an object (without sight) (meissner)
  • Requires the somatosensory association area in the parietal lobe to be functioning normally (higher order processing)
37
Q

What kind of senses does the anterolateral tract take?

A
  • Coarse touch
  • Pain
  • Temperature
  • Itch
38
Q

Where is the 2nd neuron located in the anterolateral tract?

A

Posterior horn - crosses to opposite side close to same level in white comissure ascends to thalamus

39
Q

What are the 2 different tpes of pain and what fibres are they carried by?

A
  • Discriminitive “localising” - well localised and brief via delta fibres (small myelinated)
  • Affective “suffering pain” - less localised and longer lasting via unmyelinated C fibres
40
Q

Where do discriminitive pain fibres terminate on the brain?

A
  • Discriminitive - post central gyrus
41
Q

Where do the paleospinothalamic tracts go to in the brainstem?

A

Reticular formation

42
Q

How can prolonged stimulation of the paleo-spinothalamic pathway affect mood and output?

A

Fibres can terminate in amygdala and cingulate gyrus

43
Q

What part of the brain stem prevents sleep (associated with paleospinothalamic pathway)?

44
Q

What part of the brain stimulates autonomic circuitry? - pain makes you sweat and feel sick (associated with paleospinothalamic pathway)?

A

Hypothlamus

45
Q

What part of the brain provides us with avoidance behaviours? (associated with pain pathways)?

46
Q

What part of the brain provides us with a strong memory forming circuit? (associated with paleospinothalamic pathway)?

A

Hippocampus and amygdala

47
Q

What cortical area is associated with affective pain?

A

Cingulate gyrus

48
Q

At what level do opoids work?

A

Higher levels (brain and spinal cord)

49
Q

What theory do TENS (trans-electrical nerve stimulators) apply to?

A

Gate theory - touch fibres inhibit pain fibres

50
Q

What are the main functions of the thalamus?

A
  • Conscious sensation relay and processing
  • Motor circuits
  • Emotion/memory
  • Special sense hearing and vision
51
Q

WHat control centre is thought to inhibit extreme pain?

A

Periaqueductal grey (PAG) descends to dorsal horn (substantia felatinosa via raphe nuclei) - can be activated through electrical stimulation

52
Q

What are the main paths through thalamus nuclei?

A
  • Sensory relay
  • Motor circuits
  • Limbic system
  • Special sense
53
Q

HOW THALAMUS AND CORTEX ARE CONNECTED THE WHITE MATTER BUNDLES

54
Q

Lesions in the anterolateral tract caused decreased perception of pain and temperature on what side of the body?

A

Contralateral side

55
Q

What is a cervical cordotomy?

A

Surgical procedure for terminal disease where part of anterolateral cord is lesioned (on opposite side to pain) in order to deacreased perception (pain returns after about a year)

56
Q

What conditions may affect the dorsal spinal cord?

A
  • Vitaminn B12 deficiency (SCDC)
  • HIV myelopathy
  • Tabes dorsalis (syphilis)
  • MS
57
Q

What is the function of the cerebellum?

A

Gathers information about the movements of the body, and then compares them with planned and active movements of the body. It then issues real time correctional information to achieve smooth accurate movements. Error based learning

58
Q

Do sensory fibres to the cerebellum cross over?

A

They terminate on the same side in the cerebellum to the body

59
Q

What does information from the lower body extremities travel in?

A

Fasciculus gracillis

60
Q

What does information from the upper body extremities travel in?

A

Fasciculs cuneatus

61
Q

What information is carried by the dorsal and ventral spinocerebellar tracts?

A

Proprioceptive info from muscle spindles (dorsal) and golgi organs (ventral)

62
Q

What tract fibres are susceptible to central cord pathologies?

A

Spinothalamic tract (anterolateral) fibres - cross early

63
Q

What can the anterolateral tract also be known as?

A

Spinothalamic

MD4001 Physiology (22 decks)

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