Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neurology > Primary Sensory Neurons > Flashcards

Primary Sensory Neurons Flashcards

1
Q

Where are the different receptors of the somatosensory system located?

A

They’re distributed throughout the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What modalities does the somatosensory system mediate?

A

Fine discriminatory touch = light touch, pressure, vibration, flutter, stretch
Joint and muscle position sense = proprioception
Temperature, pain and itch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the three categories of the somatosensory system?

A

Exteroceptive = cutaneous senses
Proprioceptive = monitors posture and movement
Enteroceptive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the exteroceptive somatosensory system monitor?

A

Registers info from the surface of the body by numerous receptor types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does the enteroceptive somatosensory system monitor?

A

Reports upon internal state of the body and is closely related to autonomic function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where is the first order neuron located?

A

Primary sensory afferent of PNS = cell body located in dorsal root ganglia or cranial ganglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the second order neuron located?

A

Projection neuron of CNS = cell body located in dorsal horn of spinal cord or brainstem nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where is the third order neuron located?

A

Projection neuron of CNS = cell body located in thalamic nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How many neurons make up the series of the somatosensory system?

A

Three neurons in series = end in the somatosensory cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the function of the sensory neuron terminals?

A

Transduce a stimulus into electrical activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does a sensory neuron terminal transduce a stimulus into electrical signals?

A

Stimulus opens cation selective ion channel in peripheral terminal of primary sensory afferent = elicits a depolarising receptor potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the amplitude of the receptor potential graded and proportional to?

A

Stimulus intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does a supra-threshold receptor potential generate?

A

An all or nothing AP = conducted by the axon at a frequency proportional to its amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does APs arriving at the central terminal cause?

A

The graded release of neurotransmitter on to a second order neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the different properties of sensory units?

A

Modality, threshold, adaption rate, conduction velocity and the site and extent of peripheral termination (receptive field)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does threshold relate to?

A

The intensity of a stimulus required to excite a sensory unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are some examples of low threshold receptors?

A

Low threshold units = respond to low intensity stimuli
Low threshold mechanoreceptor = mediate fine discriminatory touch
Low threshold thermoreceptors = mediate cold through to hot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are some examples of high threshold receptors?

A

High threshold units = respond to high intensity (damaging) stimuli
High threshold mechanoreceptors = respond to high intensity mechanical stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do thermal nociceptors respond to?

A

Extremes of hot (>45) or cold (<10-15)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What do chemical nociceptors respond to?

A

Substances in tissues (e.g during inflammatory response)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What do polymodal receptors respond to?

A

At least two modalities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does adaption determine?

A

Whether they change their firing rate only in response to a stimulus of changing intensity or fire continuously throughout a constant stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the features of the slow adapting response?

A

Continuous info to CNS while terminal deformed = provides info about position, degree of stretch and force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the features of the fast adapting response?

A

Detects changes in stimulus strength = number of impulses proportional to rate of change of stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the features of the very fast adapting response?

A

Responds only to very fast movements (e.g rapid vibration)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are some features of Group I fibres?

A

13-20 micrometer diameter
80-120 m/s conduction velocity
Sensory receptors for proprioceptors for skeletal msucle
Thick myelination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are some features of Group II fibres?

A

6-12 micrometer diameter
Moderate myelination
35-75 m/s conduction velocity
Sensory receptor for mechanoreceptor of skin

28
Q

What are some features of Group III fibres?

A

1-5 micrometer diameter
Thin myelination
5-30 m/s conduction velocity
Sensory receptor for pain and temperature

29
Q

What are some features of Group IV fibres?

A

0.2-1.5 micrometer diameter
No myelination
0.2-0.5 m/s conduction velocity
Sensory receptor for temperature, pain and itch

30
Q

What happens to the peripheral terminal of cutaneous afferent fibres?

A

Branch into many fine processes = tips of which can be free nerve endings or associated with specialised structures

31
Q

What is the receptive field?

A

Target territory from which a sensory unit can be excited = size varies greatly over body surface

32
Q

What is the relationship between the receptive field and innervation density?

A

Receptive field is inversely related to innervation density

33
Q

How does sensory acuity correlate with receptive field size?

A

Sensory acuity is inversely related with receptive field size

34
Q

What are some features of high density and low density innervation?

A

High density = small receptive field, high acuity

Low density = large receptive field, low acuity

35
Q

What is two point discrimination?

A

Measure of somatosensory function = also called spatial acuity

36
Q

How is two point discrimination tested?

A

By applying two sharp point stimuli simultaneously separated by a variable distance at different sites on the body surface

37
Q

How is threshold distance determined from two point discrimination testing?

A

Subject reports on whether one point or two or sensed and a threshold distance is established between the two

38
Q

What do two point thresholds match?

A

The diameter of the corresponding receptive field = regions with the highest discriminative capacity have the smallest receptive fields

39
Q

What are some examples of cutaneous receptors?

A

Free nerve endings, Meissner’s corpuscles, Merkel’s discs, hair end organs, Krause end bulbs, Ruffini endings (encapsulated), Pacinian corpuscles (encapsulated)

40
Q

What kind of innervation do free nerve endings provide?

A

Ubiquitous innervation

41
Q

What are some features of Meissner’s corpuscles?

A

Abundant in skin locations where two point discrimination is highest, not present in hairy skin

42
Q

What are some features of Merkel’s discs?

A

Distribution same as Meissner’s corpuscles but also present in moderate numbers in hairy skin, often grouped in Iggo domes

43
Q

Where are Krause end bulbs located?

A

At border of dry skin and mucous membranes

44
Q

Where are Ruffini endings located?

A

Within dermis and also present in joint capsules

45
Q

Where are Pacinian corpuscles located?

A

Within dermis and fascia

46
Q

What occurs in the Iggo dome?

A

Multiple Merkel cells are innervated by a single myelinated fibre = both are mechanosensitive

47
Q

What are the physiological divisions of skin low threshold mechanoreceptors?

A

Rate of adapting = fast adapting, slow adapting

Size of receptive field = small (type 1 unit), wide (type 2 unit)

48
Q

What do skin low threshold mechanoreceptors consist of histologically?

A

A receptor and its parent fibre type

49
Q

What are some examples of skin low threshold mechanoreceptors?

A

Free nerve endings, follicular nerve endings, Merkel cell-neurite complexes, encapsulated nerve endings

50
Q

What are some features of the receptive fields of Pacinian corpuscles?

A

Corpuscle responds when the stimulus strength increases sufficiently anywhere within the area
Larger fields than Meissner’s corpuscles

51
Q

What does the threshold for detecting vibration correspond to?

A

The tuning threshold of the mechanoreceptor

52
Q

What is grey matter subdivided into?

A

Dorsal and ventral horns, and ten distinct laminae of Rexed

53
Q

What are the sensory receptors of hairless skin?

A

Merkel cell-neurite complexes, Meissner’s corpuscles, Ruffini endings, Pacinian corpuscles

54
Q

What forms Merkel cell-neurite complexes?

A

Formed from many expanded nerve terminals, each closely associated with a Merkel cell as a synapse like structure

55
Q

What are some features of Merkel cell-neurite complexes?

A

Located in basal epithelium of skin areas with high sensory acuity
Signal sustained pressure/texture and are extremely sensitive to edges of objects

56
Q

What are Meissner’s corpuscles formed from?

A

Formed from a capsule in which several axons zigzag between modified Schwann cells

57
Q

What are some features of Meissner’s corpuscles?

A

Located close to basal epithelium of skin in areas with high sensory acuity
Sensitive to stroking/flutter and low frequency vibration

58
Q

What does the location of Merkel cell-neurite complex and Meissner’s corpuscles allow?

A

Detection of textured surfaces = also aided by their small receptive field and high density

59
Q

What are some features of Ruffini endings?

A

Collagenous core in which axons branch

Located in dermis and sensitive to drag

60
Q

Where are Pacinian corpuscles located?

A

Subcutaneously close to the periosteum of the bone

61
Q

What are some features of Pacinian corpuscles?

A

Very sensitive to vibration over higher frequency range than Meissner’s corpuscles
Act as event detectors during manipulation of objects

62
Q

What are the sensory receptors of hairy skin?

A

Merkel cell-neurite complexes, Ruffini endings, Pacinian corpuscles, hair units

63
Q

What do hair cells functionally replace in hairy skin?

A

Meissner’s corpuscles

64
Q

What do hair cells consist of?

A

Comprise follicular nerve endings that either wrap around the follicle (circumferential) or parallel with it (palisade)

65
Q

What are some features of hair cells?

A

Single afferent fibre innervates many follicles

Sensory units may be slow or fast adapting

66
Q

What are hair cells responsive to?

A

The bending of hairs = increases or decreases their firing when the hair is in motion but not when static

Neurology (48 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions