Module 6 Flashcards
first-third order sensory neurons
first order: sensory receptor, receives sensation
second order: neuron between first and third
third order: takes second order neuron and transmitts signal to brain
how is the location of a stimulation determined?
post central gyrus has a body map that maps onto what region of the cortex is activated
what kind of information is transmitted in a sensory receptor?
modality, location, intensity, and duration
what does the somatic sensory system detect?
external forces on the body, internal changes, and information about the position of limbs
where are somatic sensory receptors?
skin, muscles, tendons, joints, viscera
how is the amount of firing determined by senation?
more stretch leads to more action potentials (rate of firing is directly proportional to the magnitude of depolarization)
Ia, II afferent axons
fast conductance, large diameter, lots of myelin
use: proprioception, muscle spindle (balance)
Ab afferent axon
second most myelin
use: touch, merkel, meissner, pacinian, ruffini cells
Ag afferent axons
slowish conductance
Use: pain and temperature
C afferent axons
no myelin, slow conductance
Use: pain, temperature, itch
what is two point discrimination?
the minimum distance to perceive two stimuli as distinct (smaller is better perception)
what does it mean for a receptor to be slow to adapt?
it keeps firing when there is a continuous stimuli
what is the mechanosensory pathway for?
touch, vibration, pressure
meissner sensory receptors
Detect: movement across skin, slippage of textured objects
adapting: rapidly
corpuscle
merkel sensory receptors
detect: edges, points, shapes, texture
adapting: slow
*low two point discrimination in fingertips
also detects pain, temp, no capsulation
ruffini sensory receptors
detect: skin strech, hand shape
adapting: slow
corpuscle
pacinian sensory receptors
detect: vibrations, tool use
adapting: rapidly
corpuscle
conveying mechanosensory info to cortex from periphery afferent pathways
- two pathways (upper and lower body, cudeate and gracile), end at dorsal column nuclei of medulla
- jump over to other side, end at VPL nucleus of thalamus
- end at primary somatosensory cortex (S1)
mechanosensory info to cortex from face
- trigeminal ganlion
- projects to thalamus
- VPM nucleus of thalamus
what is the procioceptive pathway for?
position of limbs, body parts in space
group 1A afferent axons
detect limb movement, muscle changing length
group II afferent axons
detect static position (moving and stretching)
axonal 1B afferent
measures tendon tension
where do procioceptive pathways map to?
reflexes to cerebellum and cortex, everything else to dorsal column nuclei
