Sensation (3) Flashcards
How many neurons does it take to transmit information to sensory cortex?
3 neuronal chain
1st order neuron
periphery
associated with receptor
cell body in DRG
central process enters spinal cord
Where does 1st order neuron synapse with 2nd order neuron?
in spinal cord
Where is the 3rd cell body located?
thalamus
Where does the 3rd order neuron project?
to cortex
What are cells that transduce “environmental interaction” to produce an AP?
receptors
Which receptors respond to DOMS (lactic acid accumulation)?
chemoreceptors
Which receptors respond to pressure/touch?
mechanoreceptors (mechanical deformation)
Which receptors respond to taste?
chemoreceptors
What rate do free nerve endings adapt?
slowly adapting
TONIC input
What rate do ruffini endings adapt?
slowly adapting
Which receptors are non-encapsulated?
Free nerve endings, ruffini endings, merkels disks, hair endings
What rate do Merkel’s disks adapt?
rapidly adapting
Which receptors are most receptive to fine touch and velocity of touch?
Merkel’s disks
MOST rapidly adapting receptor type?
pacinian corpuscles
Which receptor can detect vibration?
pacinian corpuscles
What rate do hair endings adapt?
rapidly adapting
Which receptor category has crude awareness to joint movement tissues?
joint and muscle free nerve endings
Receptors encode different sensory information based on their structure through a process called ________ .
transduction
Transduction is the conversion of one form of energy (light, mechanical, etc) into ____________ that the nervous system can make sense of.
action potentials
What is a receptor field?
Area innervated by receptors and the single sensory axon associated with them.
If two points are applied to the same receptor field, what happens?
brain cannot differentiate - it only feels one input
If two points are applied to two receptor fields, what happens?
brain CAN differentiate - it feels two separate inputs “2 point discrimination”
Bigger receptor fields are associated with?
back, back of legs..
smaller receptor fields are associated with?
fine motor areas… lips, hands…
Crude touch, pain and temp on what kind of axon(s)?
unmyelinated and lightly myelinated axons.
Discriminative touch, vibration, joint position on on what kind of axon(s)?
large myelinated axons
Spinothalamic tract carries which signals?
crude touch, pain, and temperature
smaller axons
Dorsal column medial lemniscal system carries which signals?
Fine, discriminative touch, vibration, proprioception
larger axons
Early loss of sensation first affects?
vibration (attached to the largest axons)
What is the fxn of cortical sensory association areas?
add recognition to simple sensory processing; combine receptors to conscious experience
Babinski is also known as? What does positive response tell us?
extensor plantar response
positive response = toes flare up
indicates cortico-spinal lesion
