Sensory Receptors Flashcards
1
Q
Def of stimulus:
A
environment event that excites sensory receptors
2
Q
Def of sensation:
A
what is perceived in the brain when sensory receptors are stimulated
3
Q
Sensation can be…
A
conscious or unconscious
4
Q
Sensation differs in 3 things:
A
- modality: E form associated w/ stimulus
- quality
- quantity
5
Q
Sensory receptors are…
A
specialized to respond to specific stimulus
6
Q
Responses of activated sensory receptors are…
A
- depolarization at receptive end
- possible release of neurotransmitters at axonal end
7
Q
Primary sensory neurons:
A
- have receptors at dendritic ends
- simple unmodified dendritic ends (naked nerve endings)
- modified endings: enlarged/wrapped in CT
8
Q
What do sensory receptors monitor?
A
both internal and external conditions
9
Q
What falls under internal conditions?
A
- proprioceptors
- visceral
10
Q
What falls under external conditions?
A
- special sensory
- cutaneous
11
Q
Sensory receptors are classified as…
A
- somatic (skeletal muscle and skin)
- visceral (organs)
- special senses
12
Q
Examples of somatic receptors:
A
- proprioceptors
- cutaneous receptors
13
Q
Proprioceptors:
A
- type of somatic receptor
- sense info about body’s position in space and weight difference
- muscle spindle
- golgi tendon organ
14
Q
What do muscle spindles detect?
A
muscle length
15
Q
What do golgi tendon organ detect?
A
changes in muscle tension
16
Q
Cutanoues receptors:
A
- type of somatic receptor
- naked nerve endings
- Merkel discs
- Ruffini endings
- Meissner’s corpuscles
- Pacinian corpuscles
17
Q
Naked nerve endings detect…
A
pain b/c it is a nociceptor
18
Q
Merkel discs detect…
A
sustained pressure
19
Q
Ruffini endings detect…
A
deep pressure
20
Q
Meissner’s corpuscles detect…
A
light touch
21
Q
Pacinian corpuscles detect…
A
vibration
22
Q
Visceral receptors respond to…
A
- organ sensations
- pain
- stretch
- chemoreceptor
- baroreceptor
- osmoreceptor
23
Q
Special senses are…
A
modified neurons localized in specialized sensory organs in head
- passes info alond to afferent neurons
24
Q
What do special senses detect?
A
- vision
- hearing
- taste
- smell
- rotational/linear acceleration of head
25
Sensory receptors have a ______ field
receptive
| - can be determined by two point discrimination test
26
Two point discrimination test looks at...
- sensitive area: has smaller receptive fields (fingertips)
| - less sensitive areas: convergence of many primary neurons to one secondary neuron
27
Sensitive areas have a 1:1 relationship between...
primary and secondary neurons
28
Sensory transduction converts E of signal modality to...
graded potentials (GP)
29
T/F: types of stimuli transduced depends on receptor type
T
30
Mechanoreceptors respond to...
- mechanical deformation of receptor
- pressure
- cell stretch
- vibration
- acceleration
- sound
31
Baroreceptors monitors...
stretch of hollow structures
32
Chemoreceptors respond to...
- chemicals
- oxygen
- pH
- organic molecules
33
Nociceptors respond to...
physical and chemical damage of tissues
34
Thermoreceptors detect...
changes in temperature
35
Photoreceptors detect...
light
36
What happens to membrane when a stimulus is applied?
depolarization will alter membrane potential
37
Generator potential (GP):
- produced by stimulus acting on receptors on afferent neurons
- is the small temporary change in membrane potential
38
GP will create ______
local current: flow of ions
| - flows away from stimulated area to area w/ higher # of VG Na+ channels
39
What happens if GP has enough amplitude?
threshold will be reached and AP generated
40
Receptor potential (RP):
- produced in specialized receptor cell, which in turn stimulates afferent neurons
- can be depolarized or hyperpolarized
41
Amplitude and duration of RP regulates...
amount of neurotransmitters released
| - enough neurotransmitters released = AP generated
42
Difference between GP and RP?
- GP: produced by stimulus acting on afferent neurons (enough amplitude = AP)
- RP: produced in specialized receptors (enough neurotransmitters = AP)
43
T/F: receptors don't have adaptive abilities
F, they do because it lets body know if it needs to monitor the stimulus or be constantly aware of stimulus
44
Adaptations of receptors leads to...
decrease of GP/RP to constant intensity stimulus
45
Adaptations of receptors will produce...
a decrease of frequency of AP over time in response to constant intensity of stimulus
46
Total adaptation of receptor leads to...
loss of perception of stimulus
47
Phasic receptors:
- respond to changes in stimuli
- fast adaptation: stops responding immediately when stimulus stops changing
- sends signal only when there is a change in stimulus
48
Phasic receptors have a predictive function, which provides...
- good assessment of rate of change
- pacinian corpuscles
- hair receptors
- olfactory receptors
49
Tonic receptors:
- intensity receptors
- continue to send signal as long as the stimulus persists
- very slow/no adaptation
- keeps consistent firing rate when stimulus is applied
50
Tonic receptors are important for...
- homeostasis
| - limiting potential for injuries
51
Exampes of tonic receptors:
- nociceptors
- proprioceptors
- baroreceptors
52
Magnitude of GP/RP is directly proportionate to...
stimulus intensity (log)
53
Magnitude of GP is directly proportionate to...
rate of AP of afferent fibers (linear)
54
Information coding:
how info about a stimulus is carried in CNS
55
Sensory coding involves:
- which sensory receptors are activated
- response of sensory receptor to stimulus
- intensity and duration of stimulus
- info processing in sensory pathway
56
Aspects that can be coded:
- sensory modality: coded by pathway
| - intensity of stimulus: coded by rate of APs
57
Types of sensory modalities:
- cutaneous stimuli
| - noncutaneous stimuli
58
Cutaneous stimuli are interpreted as:
- touch
- pressure
- cold
- warmth
- pain
59
Noncutaneous stimuli are interpreted as:
- vision
- auditory
- position
- taste
- smell
60
Threshold stimulus:
- weakest stimulus that produces AP
- below this = no AP generated
- can add subthreshold stimulus to get AP (spatial and temporal summation)
61
Spatial summation:
- progessively larger # of primary afferent neurons activated simultaneously
62
Temporal summation:
- single primary afferent neuron fires multiple times in a row
63
T/F: greater stimulus usually affects a smaller area of CNS
F, should affect greater area b/c can affect more sensory receptors
64
Sensory unit:
a sensory neuron and all its receptive ends
| - activate more receptors in one sensory unit leads to more APs/sec produced
65
receptive field:
- area whose stimulation affects neuron AP
| - can overlap with multiple sensory units
66
Continuous info is provided by...
tonic receptors
67
Beginning/ending signal are provided by...
phasic receptors
68
Spatial location of stimulus:
activation of specific population of sensory neurons w/ endpoint of pathway onto cortex
- ex: lateral inhibition and somatotopic map
69
Lateral inhibition:
mechanism where transmission of signal can be inhibited laterally, which limits widespread of signal
- enhances contrast between sites of strong and weak stimulus
70
Somatotopic map:
plan of body regions in sensory cortex
71
Movement of info:
primary sensory afferent neurons in PNS to interneurons in CNS to CNS integrative areas
72
Speed of transmission is affected by:
- diameter and myelination of neurons
| - # of synapses that must be crossed (more = slower)
73
of sensory units stimulated leads to...
size of receptive field
74
Organization of relaying interneurons allows CNS to _______ info
- filter
- correlate
- summate
- sort
75
Convergence of interneurons:
```
# of signals entering neuronal pool > # exiting
- allows summation of weak signal and can filter out signal
```
76
Divergence of interneurons:
of signals entering neuronal pool < # exiting
- amplifies signal within single pathway
- can maintain signal strength and send to multiple pathways
