Physiology Flashcards
Nociceptive Pain
Intense stimuli e.g thermal, mechanical, chemical
What order of neurones are nociceptors?
First order neurones, they relay information to second order neurones in the CNS by chemical synaptic transmission
Do nociceptors have a high or low threshold?
High (only provoked by intense stimuli)
Inflammatory pain has low threshold
What type of pain causes hypersensitivity and allodynia?
Inflammatory pain
Pathological Pain
Neuropathic pain is triggered by lesions to the somatosensory nervous system that alter its structure and function so that pain occurs spontaneously and responses to noxious and innocuous stimuli are pathologically amplified
Congenital Insensitivity to Pain
A very rare condition, congenital insensitivity to pain (CIP) results due to loss of function mutations (missense or in frame deletions) in the gene SCN9A that encodes a particular voltage-activated Na+ channel (Nav1.7) that is highly expressed in nociceptive neurones
Gene that has mutations which gives rise to CIP
SCN9A
What does SCN9A encode?
Voltage activated Na+ channel (this particular one is highly expressed in nociceptive neurones)
What kind of stimuli do alpha-delta fibres respond to?
Mechanical and thermal
myelinated
Which type of fibres mediate first pain?
Alpha-delta fibres
C fibres mediate second pain (C fibres are polymodal and unmyelinated)
Where are cell bodies of nociceptors contained?
Ganglia
Where do the nociceptor dorsal root ganglia lie?
Lateral to the spinal column
(The dorsal root ganglia lie lateral to the spinal column – project centrally to the dorsal horn of the spinal cord and peripherally to the skin, muscle, tendons, joints, internal organs)
The nociceptors from which ganglia innervate the viscera?
The Nodose (inferior vagal) ganglia
