Principles of Sensory Systems

Question 1

3 common steps

Answer 1

require physical stimulus
must transform the stimulus into nerve impulse - sensory receptors in peripheral nervous system
evoke a response to the signal in the form of perception of sensation

Question 2

sensory receptors

Answer 2

are cells, not just proteins

energy from environment —–> sensory transduction —–> electrochemical signals in sensory receptors

Question 3

sensory receptors proteins

Answer 3

many receptor cells possess ion channels and GPCRs

Question 4

specificity for sensory modalities

Answer 4

achieved by structure and position of the sensory receptor
vision, smell, balance, taste, taste ==== special senses
proprioception - understanding body position - how stretched muscle is
thermal senses
pain
touch

Question 5

stimulus
receptor
location

hearing

Answer 5

mechanical
mechanoreceptor
cochlea

Question 6

stimulus
receptor
location

balance

Answer 6

mechanical
mechanoreceptor
vestibular system

Question 7

stimulus
receptor
location

vision

Answer 7

light
photoreceptor
retina

Question 8

stimulus
receptor
location

touch

Answer 8

mechanical
mechanoreceptor
skin

Question 9

stimulus
receptor
location

temperature

Answer 9

thermal
thermoreceptor
skin

Question 10

stimulus
receptor
location

pain

Answer 10

mechanical, thermal, chemical
nocireceptor
skin, interal organs

Question 11

stimulus
receptor
location

proprioception

Answer 11

mechanical
mechanoreceptor
muscles, joints, tendons

Question 12

stimulus
receptor
location

olfaction

Answer 12

chemical
chemoreceptor
nasal cavity

Question 13

stimulus
receptor
location

taste

Answer 13

chemical
chemoreceptors
tongue, pharynx, palate

Question 14

pathway of stimulus

Answer 14

stimulus —- sensory receptor activated —- membrane permeability altered —- causes receptor potential to develop —- neurot is released onto afferent neuron terminal —- action potential generated in afferent neuron terminal —- propagtes to CNS

some dont have to release neurot as theyre neurons themselevs e.g. olfactory system

Question 15

graded vs action potentials

Answer 15

muscle stretches = graded receptor potenital at dendritic portion of axon
if receptor potential is large enough, action potnital generated
more stretch = larger graded potential - reach action potential threshold

Question 16

example of direct neuronal activation

olfactory receptors

Answer 16

graded = in cilia of dendrites
soma = graded and action
axon = action potential

Question 17

sensory receptors can convey different types of info

Answer 17

modality
location
intensity
timing

Question 18

stimulus modality is coded by labelled line code

Answer 18

labelled line code:
receptor is selective for one type of stimulus energy
axons of the receptor and associated afferent neuron acts as a modality specific line of communication
axons from these neurons make connections with specific areas in CNS

stimulating afferent neurons electrically leads to perception of the associated sensation

Question 19

faulty labelled line code

Answer 19

synaesthesia

Question 20

stimulus location

Answer 20

spatial arrangement of activated receptors within a sense organ give info about the stimulus
in somatic system, a receptive field is region of skin innverated by terminals of receptor neuron
in visual system, a receptive field of a photoreceptor is the region of visual field projected onto that receptor

Question 21

stimulus intensity

Answer 21

totatl amount of stimulus energy delivered to receptor
lowest stimulus strength hat can be recieved = sensory threshold
intesnity is determined by response amplitude of receptor and therefore the firing frequency

Question 22

stimulus timing

Answer 22

onset timing - when the stimulus energy is received by receptor and causes it to fire
stimulus duration - determined by adaptation rates of receptors
adaptation = in response to continuous stimuli, the firing rate of action potentials decreases

Question 23

slowly adapting receptors

Answer 23

tonic receptors

respond to prolonged stimulation

Question 24

rapidly adapting receptors

Answer 24

phasic receptors

respond at beginning and end of stimulus