4 Sections of the spinal cord
~~> 1. Cervical
2. Thoracic
3. Lumbar
4. Sacral
A beta Fibers
~~> Large sensory fibers involved in rapidly transmitting sensation.
Responds to touch
(around 50 m/s)
A delta Fibers
~~> Slower fiber that responds to sharp pain ( around 10m/s)
C ...
✓ ~~> Allows us to perceive the texture of materials, the "slippage"
between the skin and grasped object and the small vibrations of tools.
EX Detecting change in amplitude when you're running you fingers across an
etched design.
Stimulus Response Spike Train
✓ ~~> Merkel and Ruffini cells have an onset response (dynamic phase)
and an ongoing response (static phase)
Meissner and Pacinian cells respond to the first part of the stimulus
Merkel Cells and Mechanotransduction
✓ ~~> When skin is presed:
1) Mechanically-gated ion channels in the A beta membrane open, letting in
ions (Na)
2) This causes the first ("dynamic phase") action potential
3) Mechanically-gated ion channels in the Merkel cell membrane also open,
letting in ions (Na)
4) This depolarizes the Merkel cell and results in the opening of voltage gated
Ca channels
5) As a result, a neurotransmitter (norepinephrine) is released onto the A beta
axon terminal, which contains transmitter receptors
6) This causes the second ("static") action potentials
Master01 | September, 2024/2025 | Latest update
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