Sensory -Restrepo

Question 1

transduction

Answer 1

process of detection of a sensory input and transformation of information into a change in neuronal action potential

Question 2

in sensory system, where does initial interaction with stimulus occur

Answer 2

sensory receptor cells

Question 3

examples of sensory receptor cells

Answer 3

olfactory (odorants)
photoreceptors (sense light)
mechanoreceptors (detect touch/pressure)

Question 4

2 main regions of interest in sensory receptor

Answer 4

1) receptive region (specialization associated with absorption of specific energy type)
2) synaptic region specialized to transmit info to next cell

Question 5

how do sensory receptors differ from other neurons

Answer 5

receptove region especially sensitive to 1 of a variety of physical stimuli (heat, cold, mechanical deformation, light, chemicals)

Question 6

receptor (generator) potential

Answer 6

stimulus-elicited change in membrane potential (depolarization or hyperpolarization)

Question 7

short sensory receptor cells

Answer 7

receptor potential spreads via passive electronic transmission

Question 8

which receptor types don’t need regenerative APs

Answer 8

short receptor cells

Question 9

long receptors

Answer 9

(somatosensory receptor cell)
must employ regenerative APs to carry info from receptive end to synaptic release

receptor potential only affects limited portion of cell near receptive ending

(e.g. skin mechanoreceptors, cell bodies (soma) and long axons along spinal cord that synapse with 2nd order neurons in brainstem)

Question 10

What happens after depolarization of sensory receptor cells

Answer 10

membrane depolarization in synaptic region–> opening of voltage sensitive Ca channels – vesicle fusion and release of NTs interact with lignad-gated (or G-protein-linked) receptors –> directly alter postsynaptic cells membrane potential

Question 11

NT for most sensory receptor cells

Answer 11

glutamate

Question 12

Membrane potentials arise from

Answer 12

differential conductance of membrane to certain ions

Question 13

What alters opening of ion channels in sensory receptors

Answer 13

detection of adequate stimulus by receptor proteins

Question 14

Results of opening of ion channels

Answer 14

depolarization in some neurons and hyperpolarization in others

Question 15

Example of a cell depolarizing with stimulation

Answer 15

• muscle mechanoreceptors in sensory endings that dorsal root ganglion neurons extend into muscle spindle – mechanosensitive cation channels open in response to stretch
• due to increase in cation conductance in receptive membrane
• membrane potential moves toward 0 mV
• cation conductance increases/depolarization increases in a graded fashion with the intensity of the stimulus

Question 16

Example of cell hyperpolarizing due to stimulus

Answer 16

• Rod photoreceptor
• have res;ting potentials between 0 and -70 mV (generally -30-40)
• some K channels open at rest in receptive area due to resting cation conductance open in the receptive area
• hyperpolarization response to stimulus when adequate stimulus causes some receptors of cation channels to close (K can’t get in so resting potential more negative– hyperpolarizes) –> decreased NT release

Question 17

hyperpolarization of rod photoreceptors in response to light

Answer 17

receptor protein = rhodopsin
- when cis retinal (bound to rhodopsin) absorbs light–> retinal changes conformation to all trans-retinal –> conformation change in receptor protein from rhodopsin to metarhodopsin –> stimulates G protein transductin –> activates cGMP phosphodiesterase that causes breakdown of cGMP –>decrease of cGMP –> closure of cGMP-gated cation channels –> hyperpolarization and less NT release

Question 18

Sensory systems convey info about attributes of a stimulus: what are these5 attributes

Answer 18

modality, intensity, quality, duration/ frequency, location

Question 19

Sensory modalities

Answer 19

different forms of energy converted by nervous system into different sensations
Examples: vision, hearing, smell, taste, touch and thermoreception

Question 20

information from sensory receptor cell to CNS is processed and used for what 3 main functions:

Answer 20

conscious sensation, control of movement, maintaining arousal

Question 21

where is information routed to get through cerebral cortex

Answer 21

generally information becoming conscious goes through thalamus

Question 22

T/F Separate pathways to CNS for different sensory systems

Answer 22

True

Question 23

Subdivisions of thalamus

Answer 23

• each specialized in relaying and processing info for particular sensory modality
• visual –> Lateral genticulate nucleus to visual cortex in occipital lobe
• auditory through medial geniculate nucleus (MGN) to auditorycortex in temporal lobe
• olfactory system informaiton does NOT have to relay through thalamus to get to olfactory cortex

Question 24

Receptor potential increases as _______ increases

Answer 24

intensity of stimulus

• due to fact that fraction of time transduction channel opens depends on stimulus intensity
• example – weak touch – open a small percent of time with weak tough and most of the time with strong touch

Question 25

Are transduction channels voltage dependent

Answer 25

NO!! sensitive only to adequate stimulus

Transduction channels don’t open in response to depolarization

Question 26

in Long receptor cells stimulus intensity is coded by what?

Answer 26

frequency of firing of APs

Question 27

Types of peripheral nerve fibers

Answer 27

A alpha, Abeta, Adelta, C

Question 28

A alpha fibers

Answer 28

1a - muscle spindle afferent, 1b= tendon organ afferent

• Diameter = 10-20 micrometers
• Speed: fASTEST

Question 29

A beta fibers

Answer 29

(II)

• Mechanoreceptors of skin, secondary muscle spindle afferents
• Diameter 5-10 microm
• Speed: 2nd fastest

Question 30

A delta

Answer 30

(III)

• Sharp pain, cold temperature
• Diameter: 2nd smallest
• Speed - second slowest

Question 31

C fibers

Answer 31

(IV)

• Warm temperature, burning pain, itch, crude touch
• Diameter
• Speed: smallest/slowest and unmyelinated