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What is a receptor organ
Eyes, ears, olfactory tract, skin
What is the dorsal column system?
white matter, sensory, spinal cord (all sensations follow this)
Where is the dorsal column stream?
Receptor -> DRG -> dorsal horn -> medulla (deccusation) -> Thalamus -> somatosensory parietal cortex
What is sensory transduction?
signals from the environment are transduced into a PNS electrical signal that can be conveyed to the CNS for perception (energy signals transduce from PNS to CNS)
What are the steps of sensory transduction
mechanical stimulation deforms to corpuscle
Tip of axon (unipolar cell) stretches
Axonal ion channels mechanically open
Sodium entry causes a generator potential
What is DRG
Dorsal root ganglion contains the cell bodies of sensory neurons that bring information from the periphery to the spinal cord
Herpes live here
What is the spinothalamic system
It transmits information to the thalamus about pain, temperature, itch, and crude touch
The pathways then deccusate at the level of the spinal cord, rather than in the brainstem
Major role is to sense, and interpret, signals from the environment
Has receptors and sensory processing systems to detect energy and substances in the environment
The Brain spends considerable amount of energy on what?
on noticing change or novelty in the environment
Ascending pain sensory pathway
Axons relay signal to dorsal horn, dorsal column, using glutamate and substance P; spinothalamic system, cingulate gyrus