PNS PT. 2 Flashcards
what is an indicator of a simple receptor
if dendrites of neurons are sensory neurons
describe simple receptors in three ways
most receptors; little specificity (respond to chemical, pressure, temp, trauma); not protected by accessory structures
what is an indicator of a complex receptor
dendrites are not sensory neurons
what an example of a complex receptor
photoreceptors
describe complex receptors in three ways
found in sense organs; protected by accessory cells + connective tissue; specific
what do encapsulate nerve endings sense
pressure
name four examples of encapsulated nerve endings
meissner’s corpuscle, Krause’s end bulb, pacinian corpuscle, Ruffini’s corpuscle
what do nonencapsluated nerve endings sense + whats an example
sense pain + temp. changes; example = Merkel’s discs
what are the three brain levels that work to transmit information
receptor level (sensory neurons) -> circuit level (ascending pathways) -> perceptual level (neurons in cerebral cortex)
where is the info transmission process located
somatosensory system
describe info going from first to second to third
anything that depolarizes first order sensory receptor neuron, will go to circuit level (second order)
but will not allways go to the third level (bc the second decides if we send to the third)
how does a sensation occur
stimulus must excite a receptor and an action potential must reach the cns
what are the four requirements for a sensation to occur
stimulus must match receptor specificity
stimulus must fall within receptor’s receptive field (area it monitors)
receptor must convert stimulus to graded potential
graded potentials in the first order sensory neuron must reach threshold
what are the two types of graded potentials
receptor potential (receptor is separate cell - most are special senses)
generator potential (receptor part of sensory neuron)
describe the activity of ion channels at the receptor level (aka sensory receptors aka first level) - 5 steps (ending with at circuit level)
- info enters activation gate as it opens during depolarization
- input/info flows through upstroke
- during repolarization, inactivation gate closes because cell is refractory
- once membrane potential ends, both gates close awaiting another depolarization
- now input is at circuit level
what are inotropic receptors
form an ion channel pore
give three examples of inotropic receptors
mechanoreceptor, thermoreceptor, electroreceptor
what are metabotropic sensory receptors
indirectly linked with ion channels on the plasma membrane of the cell through signal transduction mechanisms (aka some kind of second messenger is necessary, like a G-protein)
what are examples of metabrotropic sensory receptors
chemoreceptor + photoreceptor
describe the circuit/second level of somatosensory processing
deliver impulses to correct region of cerebral cortex for localization and perception of stimulus
describe ascending sensory pathways at the circuit level
consist of chains of neurons; 1st order take info from receptor level to spinal cord; inputs synapse with second order neurons in brain which synapse with third order which transfer input to the cerebral cortex
does some input go to spinal cord and never reach the brain
yes
describe the percuptal/third level of somatosensory processing
intrepration in cerebral cortex by sensory fibers
what do sensory fibers at neuronal circuits in cerebral cortex do
tell brain “who” and “where” info is coming from (aka action potential is just info and brain doesnt know how to interpret it yet)
what are three examples of sensory fiber complexity
magnitude of stimulus, quality (sweet vs bitter), pattern (melody of music)
name the six levels of perceptual complexity
percuptal detection, magnitude estimation, spatial discrimination, feature abtrasction, quality discrimination, pattern recognition
describe perceputal detection
detected that stimulus occurred
describe magnitude estimation
detect stimulus intensity (determined by frequency coding)
describe spatial discrimination
identify site of pattern of stimuli (how far can two points be before considered as one?)
describe feature abstraction
difference in properties; velvet v marble
describe quality discrimination
differentiate subsodalities of a sensation (sweet vs biter)
describe pattern recognition
take in scene and recognize patterns (dot paintings, melody)
