receptor physiology

Question 1

what is a first order sensory neuron?

Answer 1

afferent neuron with its peripheral receptor that first detects stimulus

Question 2

what is a second order sensory neuron?

Answer 2

either in spinal cord or medulla, synapses with a third order neuron

Question 3

where is a third order sensory neuron located?

Answer 3

thalamus

Question 4

what does a somatic sense sense?

Answer 4

body senses

Question 5

what does visceral senses relay?

Answer 5

information from internal organs

Question 6

what are the special senses?

Answer 6

vision, hearing, balance, taste, smell

Question 7

where are sensory receptors located and what are their purpose?

Answer 7

at peripheral endings of afferent neurons or receptor cells
detect stimuli

Question 8

what is sensory transduction?

Answer 8

conversion of different forms of energy into electrical signa;s

Question 9

what is modality?

Answer 9

different types of sensation

Question 10

what are exterocceptors?

Answer 10

used for information from the external world

Question 11

what are proprioceptors?

Answer 11

used for information from the muscleoskeletal system

Question 12

what are interoceptors?

Answer 12

used for information from internal organs

Question 13

what are photoreceptors?

Answer 13

used to respond to visible wavelengths of light

Question 14

what are mechanoreceptors?

Answer 14

receptors that are sensitive to mechanical energy

Question 15

what are thermoreceptors?

Answer 15

receptors that are sensitive to hot and cold

Question 16

what are nocioreceptors?

Answer 16

receptors that are sensitive to pain

Question 17

what are chemoreceptors?

Answer 17

receptors that detect chemicals

Question 18

what are osmoreceptors?

Answer 18

detect changes in osmotic pressure

Question 19

what is adequate stimulus?

Answer 19

requires the least amount of energy to activate that particular receptor

Question 20

what is the law of specific nerve energies?

Answer 20

the sensation characteristic of each sensory neuron is that produced by its adequate stimulus

Question 21

what are the 3 possible structures of of receptors?

Answer 21

Can be free nerve endings ( nociceptors )
Can be specialized endings of sensory neurons
Can be specialized structures that have synaptic connections with sensory axons ( photoreceptors, taste buds )

Question 22

how is a receptor potential created?

Answer 22

a stimulus alters receptors permeability
this leads to an influx of sodium
thus depolarization

Question 23

is a receptor potential graded?

Answer 23

yes

Question 24

is there a refractory period for a receptor potential?

Answer 24

no

Question 25

is summation possible for a receptor potential?

Answer 25

yes

Question 26

what is a tonic receptor?

Answer 26

a receptor that does not or slowly adaptd (muscle stretch)

Question 27

what is a phasic receptor?

Answer 27

a receptor that adapts rapidly (tactile receptors on skin)

Question 28

what are the properties of a stimulus?

Answer 28

modality
location
intensity

Question 29

describe modality;

Answer 29

A particular modality detected by a specialized receptor is sent over a specific afferent and ascending pathway to excite a defined area in the somatosensory cortex
Sensory information is mapped along specific pathways

Question 30

what is an exception to the known concept of modality?

Answer 30

synesthesia

Question 31

describe location of stimulus:

Answer 31

distinguished by the location of the activated receptive field and the pathway that is subsequently activated. sends information to the somatosensory cortex

Question 32

what are receptive fields?

Answer 32

the region of skin surface that the somatosensory neuron responds to

Question 33

what is acuity?

Answer 33

The smaller the receptive field the greater the acuity

Question 34

what influences acuity?

Answer 34

lateral inhibition

Question 35

where is the primary sensory cortex located?

Answer 35

postcentral gyrus

Question 36

describe intensity of stimulus;

Answer 36

Variable intensity = variable receptor potentials = produces variable patterns of action potentials in the CNS
Rate of action potentials is proportional to stimulus intensity

Question 37

what is adaptation?

Answer 37

a reduction in receptor potential despite sustained stimulation of the same magnitude. Helps prevent sensory overload