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MBBS - Year 1 > Physiology - Fractures and Dislocation > Flashcards

Physiology - Fractures and Dislocation Flashcards

1
Q

Nociceptors

A

Peripheral receptors of pain (noxious stimuli)

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2
Q

Types of nociceptors

A

Mechanical nociceptors
Polymodal nociceptors
Thermal nociceptors

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3
Q

Mechanical nociceptors

A

Stimulated by intense pressure

Have fast conducting myelination - give rise to sharp fast (1st) pain (localised)

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4
Q

Polymodal nociceptors

A

Respond to multiple stimuli

Afferents are C fibres

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5
Q

C fibres

A

Slower than A delta fibres - unmyelinated
Result in slow (2nd) pain - aching or burning natures
High threshold thermo, mechano and chemical receptors

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6
Q

Thermal nociceptors

A

C fibre afferents

Respond to extremes of hot and cold

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7
Q

Primary hyperalgesia

A

Occurs within areas of damaged tissue

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8
Q

Secondary hyperalgesia

A

Occurs ~ 20mins after an injury, tissues surrounding a damaged area may become supersensitive

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9
Q

What is pain proportionate to

A

Nociceptive input

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10
Q

Pain pathways

A

A delta and C fibres enter dorsal horn and interact w/ projection neurons
Ascension via spinothalamic tract to thalamus
3rd order neurons project and terminate in the 1’ somatosensory centre - determine which region of body is experiencing pain

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11
Q

Limbic cortex

A

Emotional centre

Tells us pain is unpleasant and concerning

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12
Q

Molecular sensor for noxious heat stimuli

A

TRPV1 (capsaicin - chilli)

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13
Q

Molecular sensor for noxious mechanical stimuli

A

TRPA1
TRPV4
Piezo

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14
Q

Molecular sensor for noxious chemical stimuli

A

ASIC
TRPA1
TRPV1

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15
Q

Molecular sensors for noxious cold stimuli

A

TRPM8 (menthol)

TRPA1

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16
Q

Molecular sensor for ATP

A

ATP comes from damaged tissue

P2X3

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17
Q

What happens when molecular sensor channels have been opened

A

Triggers an influx of Na+ —-> causing an action potential

Mediated by Na channels (1.8 and 1.9)

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18
Q

Where do projection neurons cross to

A

Cross to diagonal side of dorsal horn (ventral aspect)

19
Q

Anatomy of pain pathways

A

Transduction
Transmission
Modulation
Perception

20
Q

Transduction

A

Conversion of noxious stimuli into electrical energy

21
Q

Transmission

A

Electrical stimulus is sent to the dorsal horn of the spinal cord and synapse at the 2nd order neuron

22
Q

Modulation

A

Inhibition vs amplification of signal (facilitated by EAA)

23
Q

Inflammatory soup

A 
ATP
Bradykinin
PGE2
Serotonin
Histamines
COX-2 activation
Substance P
24
Q

PGE2

A

Prostaglandins

25
Q

NGF

A

Nerve growth factor

26
Q

What happens during transduction

A

Afferent fibres enter into dorsal horn and transmit signal to WDR neurons at diff laminae

27
Q

WDR neurons

A

Wide Dynamic Range neurones
Receive stimulation from both small diameter and big diameter fibres
Found in lamina V

28
Q

EAA

A

Excitatory Amino Acids

29
Q

Endogenous relievers of pain

A

Opioids
Gate theory (TENS)
NSAIDs
Local anaesthetic

30
Q

How do opioids work as an endogenous relievers of pain

A

Produce analgesia via binding and acting on opioid receptors causing body to produce endorphins - inhibit ascending pathway

31
Q

Types of pain

A

Physiological (nociceptive) pain
Pathological (neuropathic) pain
Psychogenic pain

32
Q

Pathological pain

A

Caused by damage of nerve pathway

33
Q

Psychogenic pathway

A

In depression and anxiety

34
Q

Main pain gates

A

Spinal gate
Brain stem gate
Thalamic gate

35
Q

Gate control theory

A

Concurrent activity in large-diameter (Aβ) primary afferents reduces the transmission of pain signals in small-diameter (Aδ and C) afferents due to inhibitory neuron at lamina II
Explains why rubbing skin (exciting tactile and pressure receptors) relieves pain

36
Q

Spinoreticular pathway

A

Ascension tract for pain detected by C fibres

37
Q

Where do pain pathways pass before reaching thalamus

A

Medulla, pons and midbrain

Spinothalamic and spinoreticular pathways cross at diff levels

38
Q

A- alpha fibres

A

Motor neurones

39
Q

A-beta fibres

A

Large diameter fibres

Transmit info about touch and pressure - mechanoceptor

40
Q

When is infl soup released

A

In response to injury form leaky blood vessels and damaged tissues
Directly excites nociceptors or makes them more sensitive to other agents

41
Q

NSAIDs pain relieving mechanisms

A

Inhibit COX enzymes - no PGE2 or leukotrienes produced

42
Q

Local anaesthetic pain relieving mechanism

A

Reversibly blocks the conduction of action potentials by blocking Na+ channels on axon

43
Q

Stimulation of inhibitory interneuron at lamina II

A

Stimulated by A-beta fibres

MBBS - Year 1 (93 decks)

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