sensory systems

Question 1

sensory processing (3 steps)

Answer 1

1. require physical stimulus
2. transform stimulus into nerve impulses (sensory receptors in PNS)
3. evoke response to signal in form of perception of sensation (CNS)

Question 2

sensory receptors

Answer 2

sensory receptors are cells (not just proteins)
take energy from environment and convert it into electrochemical signals in sensory receptors by sensory transduction

Question 3

sensory receptor proteins

Answer 3

many sensory receptors have ion channels (can be ligand gated) and G-protein coupled receptors

Question 4

9 sensory modalities

Answer 4

vision
smell
taste
hearing
touch
balance (vestibular)
proprioception
thermal
pain

Question 5

modality = hearing
stimulus, receptor, and location

Answer 5

mechanical
mechanoreceptor
inner ear (cochlea)

Question 6

modality = balance
stimulus, receptor, and location

Answer 6

mechanical
mechanoreceptor
inner ear

Question 7

modality = vision
stimulus, receptor, and location

Answer 7

light
photoreceptor
retina

Question 8

modality = touch
stimulus, receptor, and location

Answer 8

mechanical
mechanoreceptor
skin

Question 9

modality = temperature
stimulus, receptor, and location

Answer 9

thermal
thermoreceptor
skin

Question 10

modality = pain
stimulus, receptor, and location

Answer 10

mechanical, thermal, chemical
nociceptor
skin, viscera

Question 11

modality = proprioception
stimulus, receptor, and location

Answer 11

mechanical
mechanoreceptor
muscles, tendons, joints

Question 12

modality = olfaction
stimulus, receptor, and location

Answer 12

chemical
chemoreceptor
nasal cavity

Question 13

modality = taste (gustatory)
stimulus, receptor, and location

Answer 13

chemical
chemoreceptor
tongue, pharynx, palate, epiglottis

Question 14

basic pathway for sensing (8 stages)

Answer 14

1. stimulus
2. sensory receptor activated
3. membrane permeability is altered in sensory cell
4. receptor potential develops in sensory cell
5. neurotransmitter is released onto afferent neuron terminals
6. action potential is generated on afferent neuron terminal
7. action potential propagates to CNS
8. info integrated by CNS

stage 6 is skipped when it is a sensory neuron not a sensory cell

Question 15

stimulus modality - labelled line code

Answer 15

receptor is selective for one type of stimulus energy
axon of receptor / associated afferent neuron acts as a modality specific line of communication
axons from neurons make connections with specific areas in CNS

stimulating afferent neurons electrically leads to perception of sensation

fault = synaesthesia

Question 16

stimulus location

Answer 16

spatial arrangement of activated receptors within sense organ gives info about stimulus
locating sensation depends on receptive field size

Question 17

stimulus intensity in graded potentials

Answer 17

lowest detectable stimulus strength = sensory threshold

intensity determined by amplitude of receptor and therefore firing frequency of afferent neurons

Question 18

stimulus timing: onset timing, stimulus duration, adaptation, tonic and phasic

Answer 18

onset timing = when stimulus energy is received by receptor
stimulus duration = determined by adaptation rates of receptors
adaptation = response to continuous stimuli where firing rate of action potentials decreases
tonic = slow adapting, prolonged stimulation
phasic = rapid adapting, respond at beginning and end of stimulus