nociception, pain and analgesia

Question 1

what is the somatosensory pathway?

Answer 1

a complex network of nerves that transmit sensory information.
general somatic senses are the sense of touch, proprioception, pain, and temperature

Question 2

what is the difference between pain and nociception?

Answer 2

nociception refers to neural encoding of impending or actual tissue damage
pain refers to the subjective experience of actual or impending harm

Question 3

what is analgesia?

Answer 3

the inability to feel pain

Question 4

what is opium?

Answer 4

one of the earliest known drugs used by man; comprises of the dried sap of the opium poppy
- is sedative and analgesic

Question 5

what is morphine?

Answer 5

a strong opiate that is found naturally in opium, a dark brown resin in poppies. It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids
- highly effective analgesic

Question 6

how does morphine act in the brain?

Answer 6

• was first believed to act as an antagonist but is actually an agonist (mimics the native neurotransmitter)

Question 7

what are the specific receptors for opioids?

Answer 7

• (mu)
• (delta)
• (kappa)
• naloxone is an antagonist at all opioid receptors

Question 8

how does opioid analgesia operate in the brain?

Answer 8

• morphine injected into the lateral ventricles relives pain
• intracerebral injection of morphine induces analgesia

Question 9

what is stimulation analgesia?

Answer 9

electrical stimulation in localised brain areas suppress pain perception in areas PAG (periaqueductual grey matter), PVG (periventricular grey matter) and RVM (strove trail medulla)
- can be blocked by naloxone

Question 10

similarities between opioid analgesia and stimulus produce analgesia (SPA)

Answer 10

• effects the same areas; PVG, PAG & RVM
• both blocked by naloxone
• causes a blockade of spinal reflexes therefore both mediated at the level of the spinal cord

Question 11

levels of opioid analgesia

Answer 11

• supraspinal = opiod receptor activation in brain stem; receptor mediated
• spinal = opiod receptors activation in spinal cord
• hormonal = stress-induced analgesia

Question 12

what are alternative analgesics?

Answer 12

• TENS (transcutaneous electrical nerve stimulation) =alters transmission of nociceptive signal to brain
• acupuncture
• placebo
• hypnosis
• stress
• cognitive