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SFI Test 2 > Somatosensory Receptors > Flashcards

Somatosensory Receptors Flashcards

1
Q

What is an encapsulated receptor?

A

Sensory terminations are surrounded by a connective tissue capsule

Capsule and associated structures alter the transmission of stimulus energy

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2
Q

What are free nerve ending receptors?

A

Bare terminals of myelinated and unmyelinated axons that contact the epithelium

Functionally distinct categories: mechanical or thermal, itch receptors, nociceptors

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3
Q

What is a merkel ending?

A

Disk-shaped terminal of myelinated axons that contact merkel cells

Merkel cells contain vesicles that mediates signaling from merkel cell to axon ending

Mechanoreceptors

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4
Q

What is a hair follicle receptor?

A

Terminals of myelinated axons wrap around the base of the hair

Mechanoreceptors

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5
Q

What are the general features of encapsulated receptors?

A

Contain mechanoreceptors

Pressure applied to the skin is transmitted through the capsule to the axon endings

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6
Q

Describe Meissner corpuscles.

A

Contain layered stack of Schwann cells

Axon ending wind between the Schwann cell layers

Located just under epidermis in hairless skin

Mechanoreceptors

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7
Q

Describe Pacinian corpuscle

A

Subcutaneous

Capsule contains concentric layers of epithelial cells with fluid filled spaces

Single axon at the center

Mechanoreceptors

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8
Q

Describe Ruffini endings.

A

Located in dermis, subcutaneous, and connective tissue

Capsule contains collagen strands with intertwined axon endings

Stretching of skin applies tension to collagen strands, squeezing axon endings – direction dependents

Mechanoreceptors

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9
Q

What types of receptors are rapidly adapting?

A

Pacinian and Meissner corpuscles

Determined by capsule physical properties

Hair follicle receptors

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10
Q

How do Pacinian corpuscles rapidly adapt?

A

Capsule transmits pressure onset, but layers forming capsule quickly rearrange and dissipate forct

When pressure is withdrawn capsule layers “rebound”, deforming membrane of axon ending

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11
Q

When do Pacinian corpuscles respond best?

A

When pressure is changing rapidly

Most sensitive to fast vibrations

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12
Q

What is a tuning curve?

A

Threshold intensity vs. frequency

A receptor is most sensitive at frequency where the threshold intensity is lowest

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13
Q

What are the slowly adapting receptors?

A

Merkel

Ruffini

Free nerve endings

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14
Q

What is the only high threshold receptor?

A

Free nerve endings that function as mechanoreceptors

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15
Q

Where are receptive fields smallest? Largest?

A

Smallest - digits of hand

Largest - Trunk and limbs

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16
Q

What is the spatial resolution for a small receptive field?

A

High spatial resolution

17
Q

What is the function of Pacinian corpuscles?

A

Respond best to fast vibrations or changes in pressure

Robust response when object is grasped in hand

“event detectors”

18
Q

What is the function of Merkel cells?

A

Signal weight, form and surface features of objects contacting skin

Sustained response - signal steady pressure exerted by edges of objects held in hand

19
Q

What is the function of Meissner corpuscles?

A

Most abundant receptor type in hand

Rapid adaptation - detect textures and edges as the hand is moved over surfaces

20
Q

What two receptors are needed for reading Braille?

A

Merkel and Meissner

Provide sensory information with high spatial and temporal resolution

21
Q

What is the function of Ruffini endings?

A

Respond to stretching of skin

Signaling posture and movements of body including hand and mouth

22
Q

What is the function of nociceptors?

A

Respond to noxious mechanical, thermal, and chemical stimuli

Free nerve ending

23
Q

What is the function of itch receptors?

A

Respond to chemical stimuli, including histamine

24
Q

What is the function of free nerve mechanoreceptors?

A

Respond to non-noxious mechanical stimuli with low sens/high threshold

25
Q

What is the function of free nerve endings in muscle?

A

Provide pain sensory information about muscle injury or overuse

26
Q

What are the three Joint receptors?

A

Free nerve endings

Ruffini endings

Pacinian corpuscles

27
Q

What is the path of information flow from the peripheral nerve to the CNS?

A

Receptor –> peripheral nerve –> dorsal root–> CNS

28
Q

What are A-beta fibers?

A

Most cutaneous mechanoreceptors: large diameter, myelinated, fast conduction velocity

29
Q

What are A-delta fibers?

A

Hair follicle receptors and some free nerve endings

Small diameter, lightly myelinated, conduct more slowly than large diameter myelinated axons

30
Q

What are C fibers?

A

Small diameter, unmyleinated axons of free nerve endings

Polymodal nociceptors, and itch receptors

31
Q

What type of pain do A-delta fibers transmit?

A

Fast pain response

Perceived as sharp, pricking, localized

32
Q

What type of pain do C fibers transmit?

A

Slow pain response

Perceived with delay compared to fast pain

Aching, throbbing, burning

SFI Test 2 (9 decks)

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