Sensory systems Flashcards
definition: adequate stimulus
a stimulus that affects only one specific receptor (under normal conditions)
what is the difference between receptor potentials and action potentials?
- receptor potentials are graded - function depends on size 2. a receptor potential can become an action potential if depolarization of the primary afferent ending occurs
how does the nervous system know “what” a stimulus is?
labeled line principle - a stimulus anywhere along the chain of neurons from receptor to higher brain centers evokes the same response
how does the nervous system know “where” a stimulus is?
- law of projection - if a neuron in a sensory pathway is stimulated the subject perceives the stimulus as being in the location of the sensory receptor for that pathway 2. somatosensory cortex
what is the function of lateral inhibition?
makes localization more accurate
how does the nervous system code for stimulus duration?
- maintain continuous signal during stimulation 2. have on-signal and off-signal
how does the nervous system code for signal strength?
- frequency code - increasing frequency of impulses 2. population code - increasing number of fibers activated
what is an example of a non-adapting receptor?
nociceptor
what is an example of a slowly adapting (tonic) receptor?
Merkel cell
what is the function of a slowly adapting (tonic) receptor?
continuous information about stimulus strength and duration
what are two examples of rapidly adapting (phasic) receptors?
pacinian corpuscles and meissner’s corpuscles
what is the disadvantage of rapidly adapting (phasic) receptors?
cannot give continuous signal in response to continuous stimulus
what is the advantage of rapidly adapting (phasic) receptors?
can signal change in stimulus intensity
which type of stimulus is useful for giving information about stimulus strength and duration?
slowly adapting (tonic)
which type of stimulus is useful for giving information about change in stimulus intensity?
rapidly adapting (phasic) receptors
which type of receptors extract dynamic information such as velocity and acceleration?
rapidly adapting (phasic) receptors
where are merkel cells located? what is their function?
- base of epidermis 2. static discrimination of shapes, edges, textures
where are meissner’s corpuscles located? what is their function?
- high density in fingertips and closer to surface 2. sensory feedback information needed for efficient control of grip
where are pascinian corpuscles located? what is their function?
- subcutaneous tissue 2. vibration
what kind of information is carried by the dorsal columns?
- tactile discrimination 2. vibration 3. proprioception
where does information in the dorsal columns decussate?
caudal medulla
what kind of information is carried by the spinothalamic tracts (anterolateral system)?
pain and temperature
where does information in the spinothalamic tracts (anterolateral system) decussate?
spinal cord
which type of nerve fiber conducts information at 100 m/s? 50 m/s? 20 m/s? 1 m/s?
- 100 m/s - Aa 2. 50 m/s - AB 3. 20 m/s - Ad 4. 1 m/s - C
Aa fibers are associated with which functions / structures?
- alpha motor neuron 2. muscle spindle primary ending 3. golgi tendon organ afferent
AB fibers are associated with which functions / structures?
- muscle spindle secondary endings 2. cutaneous mechanoreceptors
Ay fibers are associated with which functions / structures?
axon of gamma motor neuron to muscle spindle fibers
C fibers are associated with which functions / structures?
sympathetic postganglionic axons
