sensory physiology- general principals Flashcards Preview

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Flashcards in sensory physiology- general principals Deck (32):
1

what are the types of sensory receptors?

Mechanoreceptors

Thermoreceptors

Photoreceptors

Chemoreceptors

Nociceptors

2

Physical (direct) transduction:

Interaction of stimulus with membrane protein opens ion channel

3

examples of direct/physical transduction

somatosensory, vestibular, auditory, taste

4

Molecular transduction:

molecular interaction of stimulus with membrane protein
(e.g. G-protein)

5

examples of molecular transduction

vision, taste, olfaction

6

what are the steps that occur during "direct" transduction in the taste system?

1. Na+ enters through “ENaCs”
(epithelial Na+ channels)

2. Action potentials lead to Ca++ entry

3. Release of ATP as neurotransmitter

7

what taste utilizes molecular transduction?

sweet, amino acids, bitter

8

what are the steps involved in molecular (g-protein coupled) transduction of taste?

(give the example for "sweet" tastes)

1.Sugars bind to receptor coupled to G-protein

2. Release of intracellular Ca++ activates TRPm5 channel
(Transient Receptor Potential)

3. Depolarization leads to action potentials &
release of neurotransmitter ATP

9

which molecule is the "key" in the pathway for sensing sweetness?

TRPm5 channel

transient receptor potential channel

10

TRP channels are Cation ion channel that can pass _______ with a large variety of activating mechanisms

calcium ions

Ca2+

11

what are some examples of activating mechanisms for TRP channels?

Intracellular Ca++
temperature
chemicals
sound
light
pH and osmolarity
mechanical

12

how can the nervous system code for the intensity of a stimulus?

A) increase stimulus intensity
B) increase receptor potential
C) increase the number of action potentials

13

T/F: the threshold value is a known, quantifiable number for a neuron

False- it is not a precise value, its a statistical concept

defined as the stimulus intensity detected on 50% of trials

14

the ________ Can be affected by psychological, neurological, or pharmacological factors

threshold

15

what are the common stimulus attributes coded by sensory systems?

A) Modality & quality (what?)
B) intensity (how much?)
C) location (where?)
D) duration (when?)

16

the _________ is what a receptor (or neuron) is sensitive to

receptive field

17

T/F: in a single neuron, location and intensity can be confounded (confused)

true

18

how does our body prevent the confounding of location and intensity?

Across neuron coding

use multiple neurons to identify location

19

how is olfactory quality determined?

Comparing activity across olfactory fibers

20

what is lateral inhibition?

the capacity of an excited neuron to reduce the activity of its neighbors

-vital for determining the location of a stimulus

21

what type of inhibition occurs when a hyperpolarized axon terminal leads to less Ca++ entry and less neurotransmitter release

Presynaptic inhibition

22

what occurs during postsynaptic inhibition?

EPSPs and IPSPs interact: spatial & temporal summation

23

describe the sensory pathway for the auditory system:

(start at the hair cell)

1.Hair cells (receptor cells) in cochlea (inner ear)
2. Innervation by CN VIII nerve
3. CN VIII nerve synapses in cochlear nuclei
4. Ascending sensory pathway to cortex
5. Efferent pathway from superior olivary nuclei

24

T/F: Superior olivary nucleus has descending
Pathway to auditory receptor cell

true

25

Efferents from the __________ synapse on hair receptor cells

superior olive

26

what type of synapse occurs between fibers of the superior olive and hair receptor cells?

Synapse is an inhibitory nicotinic receptor
(Ca++ activated K+ channel leads to hyperpolarization)

27

what is the result of innervation of the hair receptor cells by the superior olive?

functions to "set the gain" of receptor neuron

-can lessen its firing rate (loud concert---- superior olive limits signals coming from hair cells)

28

what are the 3 types of Topographic Maps? what does each represent?

Somatotopic map
body representation

Tonotopic map
auditory pitch representation

Retinotopic map
visual field representation

29

the __________ is a visual representation of our bodies somatotopic map (body representation)

homunculus

30

what can effect sensory maps?

-injury

-experience

31

what occurs during "central sprouting"?

what type of sensory mapping is it associated?

-in the event of a lesion to one neuron, its neighbor may project a dendrite and replace its function

-associated with neurological injury of the sensory map

32

how can experience affect the sensory map of an individual?

Synaptic efficacy: long-term potentiation

New synapses

Loss of inhibition