Somatosensation II Flashcards
What are the two major pathways of the somatosensory system?
β Dorsal column
β spinothalamic tract
What does the dorsal column receive inputs from?
β Large diameter myelinated afferents : tactile
What does the spinothalamic tract receive inputs from?
β small diameter
β thinly myelinated
β coarse touch, nociception and temperature sensitivity
What happens if there is a cut on one half of the spinal cord?
β You interrupt all the ascending axons on one side
What are the two types of pain?
β Sensory discriminative
β Affective motivational
What are nociceptors?
β Neurons specialized for the detection of painful stimuli
What are the 3 types of nociceptors?
β Mechanical
β Chemosensory
β Thermal
When does temperature become painful?
β 45 degrees or higher
What is the difference between non nociceptive and nociceptive thermal receptors?
β non nociceptive plateau above a certain range
β nociceptors donβt response until the temperature approaches the range that is deemed painful
What is the TRPV1 receptor involved in?
β Transduction of noxious heat
What kind of a receptor is TRPV1?
β Ion channel that allows both Na+ and Ca2+ to pass
What can activate TRPV1 and why?
β Capsaicin
β it is lipid soluble
What does capsaicin binding to TRPV1 cause?
β Activation of thermal nociceptor
What is the conduction of the A delta fibres like?
β Slowest of the myelinated fibres
β Conduct moderately compared to C fibres
How do C fibres conduct?
β Unmyelinated
β Slowly
What pain does the A delta fibre mediate?
β Mediates the sharp first pain
What pain does the C fibre mediate?
β second dull burning pain