0520 Biological Basis of Pain Flashcards
• Explain the difference between somatosensation and pain • Outline the range of responses to pain evoked from different structures of the body • Explain the difference between tactile sensory receptors and nociceptors • Describe the different varieties of nociceptors • Explain how nociceptors can be modulated • Summarise the afferent pathways of somatic and visceral pain • Describe the ascending neural pathways of tactile and pain/temp pathways from the periphery to the brainstem/corte
Describe pain. What is the difference between nociception and pain
Pain is an unpleasant sensory and emotional experience. Nociception is the sensory process of carrying signals to mediate pain. They are not mutually inclusive
What is hyperalgesia and allodynia? What is a potential cause of each
Hyperalgesia is an increased sensitivity to nociceptor activation (from tissue damage or reaction to it). Allodynia is perceived pain from normally non-nociceptive stimulia (often changes in CNS)
Give atleast 2 response to superficial (skin) and deep pain
Skin = brisk movement, invigoration and icrease in pulse. Deep = inactivity, slowing of pulse, decrease blood pressure, sweating, nausea
What is acute and chronic pain ? What are their causes/functions?
Acute is short lasting pain, often in response to injury (warning system). Chronic pain is long lasting pain, often physiological (indication of illness/disease)
What are the differences between somatosensation and pain neural pathway
Primarily how the thalamus (spinothalamic tract vs dorsal column)
Pain = dorsal horn - zone lissaur and relay to thalamus via spinothalamic tract (synapse in substantia gelatinosa. Somatosensation = dorsal horn - dorsal colum - thalamus (synapse in dorsal horn
List the different types of mechanoreceptors (Identify whether they are fast/slow (F/S) and superficial or deep (S/D)
Meissner (F, S) pacinian (F,D) Merkel (S,S) Ruffin (S,D) Hair
List the different types of nociceptors. Which two are fast (A delta axons)
Thermal (A-delta) , Mechanical (A-delta) , C-polymoidal (C), Chemical (C) Mechanoheat-insensitive afferent (C)
Which types of axons do non-nociceptive and nociceptive afferents travel? List them from fastest to slowest
Non-noci = A-alpha, beta and delta. Noci = A-delta and C
What is nociceptor modulation? Is it post or presynaptic modulation? Give at least 3 examples of it
It a change in excitability of nociceptors due to chemical mediators from injury. It is presynaptic modulation. Examples include bradykinin, prostaglandins, substance P and histamine
What is neurogenic inflammation
Inflammation caused by release of chemical mediators from peripheral nerve terminals
Briefly describe the neural pathway of visceral and cutaneous pain
Signals Join at the sympathetic ganglion of the Autonomic NS. Travel through dorsal rt ganglion. Enter dorsal horn and cross to contralateral side. Ascend via spinothalamic tract to thalamus
What is referred pain and what causes it
Referred pain is perception of pain away from a site of origin. It is caused by cross-interactions between nociceptive viscera and cutaneous inputs
List the 4 pathways to the somatosensory cortex
Spino-spinal, spinothalamic, spinoreticular and spinomesencephalic
What sensations is the spinothalamic tract responsible for
Pain locaiton, intensity, snesory quality and emotional component
What are some inputs of the spinothalamic tract (name at least 2 )
cutaneous and visceral nociceptors, noxious stimulationf rom muscle and joints and convergant inputs from cutaneous receptors
