Sensory systems

Question 1

definition: adequate stimulus

Answer 1

a stimulus that affects only one specific receptor (under normal conditions)

Question 2

what is the difference between receptor potentials and action potentials?

Answer 2

1. 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

Question 3

how does the nervous system know “what” a stimulus is?

Answer 3

labeled line principle - a stimulus anywhere along the chain of neurons from receptor to higher brain centers evokes the same response

Question 4

how does the nervous system know “where” a stimulus is?

Answer 4

1. 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

Question 5

what is the function of lateral inhibition?

Answer 5

makes localization more accurate

Question 6

how does the nervous system code for stimulus duration?

Answer 6

1. maintain continuous signal during stimulation 2. have on-signal and off-signal

Question 7

how does the nervous system code for signal strength?

Answer 7

1. frequency code - increasing frequency of impulses 2. population code - increasing number of fibers activated

Question 8

what is an example of a non-adapting receptor?

Answer 8

nociceptor

Question 9

what is an example of a slowly adapting (tonic) receptor?

Answer 9

Merkel cell

Question 10

what is the function of a slowly adapting (tonic) receptor?

Answer 10

continuous information about stimulus strength and duration

Question 11

what are two examples of rapidly adapting (phasic) receptors?

Answer 11

pacinian corpuscles and meissner’s corpuscles

Question 12

what is the disadvantage of rapidly adapting (phasic) receptors?

Answer 12

cannot give continuous signal in response to continuous stimulus

Question 13

what is the advantage of rapidly adapting (phasic) receptors?

Answer 13

can signal change in stimulus intensity

Question 14

which type of stimulus is useful for giving information about stimulus strength and duration?

Answer 14

slowly adapting (tonic)

Question 15

which type of stimulus is useful for giving information about change in stimulus intensity?

Answer 15

rapidly adapting (phasic) receptors

Question 16

which type of receptors extract dynamic information such as velocity and acceleration?

Answer 16

rapidly adapting (phasic) receptors

Question 17

where are merkel cells located? what is their function?

Answer 17

1. base of epidermis 2. static discrimination of shapes, edges, textures

Question 18

where are meissner’s corpuscles located? what is their function?

Answer 18

1. high density in fingertips and closer to surface 2. sensory feedback information needed for efficient control of grip

Question 19

where are pascinian corpuscles located? what is their function?

Answer 19

1. subcutaneous tissue 2. vibration

Question 20

what kind of information is carried by the dorsal columns?

Answer 20

1. tactile discrimination 2. vibration 3. proprioception

Question 21

where does information in the dorsal columns decussate?

Answer 21

caudal medulla

Question 22

what kind of information is carried by the spinothalamic tracts (anterolateral system)?

Answer 22

pain and temperature

Question 23

where does information in the spinothalamic tracts (anterolateral system) decussate?

Answer 23

spinal cord

Question 24

which type of nerve fiber conducts information at 100 m/s? 50 m/s? 20 m/s? 1 m/s?

Answer 24

1. 100 m/s - Aa 2. 50 m/s - AB 3. 20 m/s - Ad 4. 1 m/s - C

Question 25

Aa fibers are associated with which functions / structures?

Answer 25

1. alpha motor neuron 2. muscle spindle primary ending 3. golgi tendon organ afferent

Question 26

AB fibers are associated with which functions / structures?

Answer 26

1. muscle spindle secondary endings 2. cutaneous mechanoreceptors

Question 27

Ay fibers are associated with which functions / structures?

Answer 27

axon of gamma motor neuron to muscle spindle fibers

Question 28

C fibers are associated with which functions / structures?

Answer 28

sympathetic postganglionic axons