Pain and analgesics 1

Question 1

What is pain?

Answer 1

The subjective conscious appreciation of a stimulus that is causing, or threatening to cause, tissue damage

Question 2

What is nociception?

Answer 2

The physical process of detection and transmission of damaging or potentially damaging (noxious) stimuli

Question 3

What are nociceptors?

Answer 3

Structures that detect noxious stimulus

Question 4

What is algesia?

Answer 4

The induction of a condition leading to nociception and pain

Question 5

What is analgesia?

Answer 5

Reduction or prevention of either nociception or pain without loss of consciousness

Question 6

What is the detection of touch?

Answer 6

Mecanoception

Question 7

Which specific structures are involved in the perception of touch?

Answer 7

Merkel’s Disc, Pacinian Corpuscle, Meissners Corpuscle

Question 8

What are the two main types of nociceptor?

Answer 8

Polymodal, mechanical

Question 9

What type of mechanical stimuli do both types of nociceptor respond to?

Answer 9

High intensity

Question 10

What level of thermal input can stimulate polymodal nociceptors?

Answer 10

> 45 degrees, <10 degrees

Question 11

What level of thermal stimuli can stimulate mechanical nociceptors?

Answer 11

> 60 degrees

Question 12

What is the order of structures for detecting a noxious stimulus?

Answer 12

Skin/viscera–> Sensory receptor–> primary afferent axon–> spinal cord

Question 13

What are the types of receptor in nociceptors?

Answer 13

ASIC (acid sensing ion channel), Purinergic receptors (P2x3), Voltage gated Na+ channels, VR-1/TRPV-1

Question 14

What is the main agonist of ASICs?

Answer 14

Protons

Question 15

What is the main agonist of Purinergic receptors?

Answer 15

ATP

Question 16

What type of stimulation do purinergic receptors respond to?

Answer 16

High intensity mechanical stimulation

Question 17

What type of stimulation do voltage gated sodium channels respond to?

Answer 17

Mechanical stimulation

Question 18

What is the main agonist of VR-1/TRPV-1?

Answer 18

H+, high levels of heat and capsaicin

Question 19

Speed of nociceptive APs compared to touch APs?

Answer 19

Slower

Question 20

Why are nociceptive APs slower than touch ones?

Answer 20

The C fibres are very thin and unmyelinated

Question 21

Which type of fibre is used for nociception?

Answer 21

C and a delta

Question 22

Which type of nociceptor is linked to c fibres?

Answer 22

Polymodal

Question 23

Which type of nociceptor is linked to A delta fibres?

Answer 23

Mechanical

Question 24

Why do APs flow down Adelta fibres quicker than C fibres?

Answer 24

The Adelta fibres are myelinated

Question 25

Why is there an initial pain felt, then a throbbing?

Answer 25

Different fibres transmit at different speeds so one transmits slower after the other

Question 26

Which fibres are responsible for the initial pain?

Answer 26

A delta

Question 27

Which pain fibres are responsible for the second pain?

Answer 27

C fibres

Question 28

Which receptors detect reasonable temperatures (10-40 degrees)?

Answer 28

Thermoreceptors

Question 29

Which receptors detect extreme temperatures?

Answer 29

Cold/heat pain receptors

Question 30

Why do thicker fibres transmit APs quicker?

Answer 30

There is less resistance

Question 31

Where does sensory input enter the spinal cord?

Answer 31

Through the dorsal root

Question 32

Where is the first synapse (in the spinal cord) that is responsible for nociceptive input into the brain?

Answer 32

The most dorsal part of the spinal cord

Question 33

Where does the AP go after it has gone through the first synapse in the spinal cord?

Answer 33

Crosses over to the other side of the body and goes up into the brain

Question 34

What can the somatosensory part of the cortex receive input from?

Answer 34

Touch and nociception

Question 35

What does the somatosensory cortex do with the touch and nociception?

Answer 35

Tells the brain where it has come from

Question 36

Role of insular and anterior cingulate cortex in nociception?

Answer 36

Tells the brain that it is pain that is being experienced, affect your mood

Question 37

How is the body mapped regarding pain perception and location?

Answer 37

As you go round the outside of the somatosensory cortex, different parts of it receive input form different body areas

Question 38

What is the pain pathway to the brain?

Answer 38

Spinothalamic pathway/tract

Question 39

Why is pain referred?

Answer 39

Not enough space in somatosensory cortex to have an acute sensation to map every part of the bodys pain

Question 40

Which body parts have a good pain mapping (know where the pain is coming from)?

Answer 40

Skin

Question 41

Which body parts have a poor pain mapping (don't know where the pain is coming from)?

Answer 41

Internal organs

Question 42

Where does pain sourced in the oesophagus feel like its coming from?

Answer 42

Heart

Question 43

What can hurt when having a heart attack?

Answer 43

Left arm

Question 44

Which neurons are shared in referred pain?

Answer 44

Second order

Question 45

What is the second order neuron?

Answer 45

The one after the first synapse in the spinal cord

Question 46

What is hyperalgesia?

Answer 46

Increased response to a noxious stimulus

Question 47

What is allodynia?

Answer 47

Painful responses to a non-noxious stimulus

Question 48

Why is hyperalgesia a thing?

Answer 48

To protect already injured/damaged areas of the body

Question 49

How does nociceptor sensitisation work?

Answer 49

Cut skin--> skin cells break--> intracellular components of skin cells is released into extracellular space--> some of these components are H+, ATP, K+ which are nociceptor agonists

Question 50

Why does an elevated conc of extracellular K+ increase the amount of APs fired from a neuron?

Answer 50

Conc grad is disrupted meaning it is harder for the neurons to repolarise, makes them more excitable

Question 51

What is unusual about nociceptive neurons?

Answer 51

They can release NTs from their dendritic end

Question 52

Which NT is released from the dendritic end of nociceptive neurons?

Answer 52

Substance P

Question 53

What does substance P do to blood vessels?

Answer 53

Activate receptors on blood vessels that makes them leaky

Question 54

Outcome of substance P's action on blood vessels?

Answer 54

More nociceptor agonists are released, generating more nociceptive APs

Question 55

Which cells does substance P recruit?

Answer 55

Mast cells

Question 56

Action of mast cells?

Answer 56

Release histamine which makes blood vessels leaky

Question 57

Which three molecules are used for healing the part of the body that has been damaged?

Answer 57

Bradykinin, prostagladin, neural growth factor

Question 58

What does nerve growth factor do?

Answer 58

Sensitise the nociceptors by lowering their threshold for opening

Question 59

What is peripheral sensitization?

Answer 59

Increased sensitivity of peripheral nociceptors

Question 60

What is central sensitization?

Answer 60

Increased transmission in spinal cord

Question 61

Which fibres do itch sensations travel down?

Answer 61

Adelta and C

Question 62

Difference between pain and itch?

Answer 62

Analgesics don't inhibit itch, can imagine an itchy sensation but not a painful one

Question 63

What kind of input cures an itch?

Answer 63

Nociceptive (scratching it hard)