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Physio Test 4 > Sensory Receptors > Flashcards

Sensory Receptors Flashcards

1
Q

Transduction

A

the process where a stimulus is converted into physiologically useful information

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2
Q

Nociceptor:

A

noxious stimuli receptors; pain

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3
Q

Mechanoreceptors

A

most varied group, respond to physical deformation, includes receptors for touch and vestibulocochlear system

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4
Q

Chemoreceptors

A

respond to chemicals including taste, smell, internal stimuli such as pH, metabolite concentration

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5
Q

Graded response:

A

amplitude of the receptor potential increases with increasing stimulus intensity over a wide range

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6
Q

Decremental conduction:

A

amplitude gets smaller and time course longer as the receptor potential spreads away from its site of origin

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7
Q

Generator potential:

A

depolarization of primary sensory endings produced by a stimulus, leads to action potentials in the primary afferent fiber if depolarization is large enough

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8
Q

A ___________________ response is maintained throughout stimulus.

A

Slowly adapting (tonic) receptors

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9
Q

A ______________________receptor response quickly diminishes to a maintained stimulus, detect the rate of change of a stimulus and stop firing when stimulus is constant.

A

Rapidly adapting (phasic) receptors

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10
Q

What are the two reasons for adaptation?

A

1) Structural changes in the receptor itself (e.g. Pacinian corpuscle)
2) Accommodation in the sensory ending

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11
Q

Mechanoreceptors - (all myelinated A-b except free nerve endings is ________)

A

A-d

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12
Q

__________________ receptors: non-encapsulated, found in hairy skin, some are slowly adapting and others are rapidly adapting, detect light touch

A

Hair follicle

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13
Q

This type of receptor is encapsulated, occur in superficial layers of glabrous (hairless) skin especially fingertips, rapidly adapting, respond well to low frequency 20-50Hz vibrations, small receptive fields, response for fine tactile discrimination. What is it?

A

Meissner’s corpuscle

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14
Q

___________ receptor: non-encapsulated, found in superficial layers of hairy & glabrous skin, slowly adapting, small receptive fields, sense pressure, aids in fine tactile discrimination

A

Merkel

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15
Q

This receptors is encapsulated, subcutaneous over entire body, rapidly adapting, large receptive fields, most sensitive to vibrations 200-300Hz. What is it?

A

Pacinian corpuscle

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16
Q

This receptor is encapsulated, widespread distribution in deep dermal layers, slowly adapting, large receptive fields, respond best to stretch of overlying skin. What is it?

A

Ruffini ending

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17
Q

This receptor is non-encapsulated, found all over the body, probably both rapidly & slowly adapting, non-discriminatory (crude) touch. What is it?

A

Free nerve endings

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18
Q

Cold receptors: most numerous temperature receptor, respond between ___________ degrees C, axons are myelinated A-d.

A

10-38

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19
Q

Warm receptors: respond between 30-45C, axons are _____________ fibers

A

C fibers

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20
Q

Nociceptors: free nerve endings sensing noxious stimuli: _____ fibers mediate fast, sharp, localized pain C fibers mediate slow, aching, diffuse pain

A

A-d

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21
Q

Stretch receptors: important for both proprioception & motor control: muscle spindles-respond to muscle stretch; Golgi tendon organs: respond to ______________________

A

muscle tension

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22
Q

What type of reflex is an involuntary action that often never intrudes consciousness?

A

Spinal reflex

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23
Q

Simplest reflex in terms of number of neurons involved (2) and number of synapses (1). Most common of these is the knee jerk, but there are others: jaw jerk, biceps, Achilles tendon, brachioradialis

A

Stretch reflex

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24
Q

Muscle spindle is made up of motor neurons and specialized sensory nerve endings embedded in 2 types of modified striated muscle fibers called ___________ fibers. All this is encapsulated and attached to connective tissue in the muscle in parallel with extrafusal fibers.

A

intrafusal

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25
Q

Nuclear bag fibers: intrafusal fibers which contain numerous nuclei packed in a center bag area. They are __________ receptors which sense rate of change in muscle length

A

Dynamic

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26
Q

Nuclear chain fibers: shorter thinner intrafusal fibers containing a single row of nuceli. They have _____________ receptors which report overall muscle length

A

Static

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27
Q

Primary sensory spinal reflexes are what type of receptors and where are they found?

A

– Group Ia afferent

– Found on both types of intrafusal fiber (thus relays both dynamic and static information)

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28
Q

Secondary sensory spinal reflexes are what type of receptors and where are they found?

A

– Group II afferent

– Found chiefly on nuclear chain fibers (relays static info)

29
Q

Motor nerve endings of intrafusal fibers are from ____________-motoneurons

A

gamma

30
Q

What type of nerve endings control length of intrafusal fibers and maintains sensitivity of the spindle?

A

Motor nerve endings of spinal reflex

31
Q

What are the periodontal mechanoreceptors?

A

Ruffini-type endings

32
Q

What type of receptors are slowly adapting and respond to forces applied ot the teeth?

A

Ruffini-type endings (mechanoreceptors)

33
Q

T/F - Dental pulp contains sensory fibers and autonomic fibers (to blood vessels)

A

True

34
Q

Is the innervation density of dentin uniform throughout?

A

NO!

Greatest innervation at tip of pulp and least along the roots. This DOES NOT correlate with pain sensitivity

35
Q

What fibers respond to mechanical stimulation of dentine (drilling, probing)? (also respond to thermal stimuli)

A

A-delta

36
Q

What fibers in the pulp are polymodal and respond to mechanical, chemical and thermal stimuli?

A

C fibers

37
Q

_______________ theory - direct transmission of the stimulous through the tooth structure to stimulate nociceptive endings.

A

Neural theory

38
Q

__________________________ theory - stimulus is transmitted by odontoblasts to nociceptors via synaptic contacts.

A

Odontoblastic transduction theory

39
Q

_________________ theory - stimulus produces movements of dentinal fluid within the dentinal microtubules, fluid movement stimulates nociceptors.

A

Hydrodynamic theory

40
Q

WHich of the 3 theories proposed to explain dental pain is the widely accepted theory?

A

Hydrodynamic theory

41
Q

What has the highest density of innervation of any structure in the body?

A

Corneal innervation

42
Q

What fibers are present in the cornea?

A

A-delta and C fibers

43
Q

What is the primary function of innervation in the cornea?

A

Maintenance and repair of the corneal epithelium. The nerves release trophic factors which maintain a healthy cornea and promote wound healing after corneal injuries..

44
Q

What is another function of innervation of the cornea other than maintenance and repair?

A

Monitors injury as well as involved in reflexes that affect secretory activity of lacrimal and meibomian glands.

45
Q

Knee jerk reflex (phasic) - Tap on tendon stretches _______________________ endings on intrafusal fibers

A

quadriceps (extensor) deforms annulospiral

46
Q

In a knee jerk reflex, action potentials in group ___ fibers produces monosynaptic excitation of alpha-motoneurons to quadriceps

A

Ia

47
Q

In the knee jerk reflex collaterals of group Ia fibers synapse on inhibitory interneurons to alpha-motoneurons of the ___________ muscles.

A

hamstring

48
Q

As a result of knee jerk reflex, quadriceps are excited and hamstrings inhibited, this arrangement is known as _________________ and occurs in all the spinal reflexes

A

reciprocal innervation

49
Q

The receptor for inverse stretch reflex is ________________________.

A

Golgi tendon organ

50
Q

What does the golgi tendon organ report?

A

Muscle tension

51
Q

What fiber group is involved in inverse stretch reflex?

A

Ib fibers

52
Q

Inverse stretch reflex involves a two synapse path. What are the two synapses?

A

Ib fibers from contracting muscle synapse on inhibitory interneuron which then inhibits alpha-motorneurons to the contracting muscle. Collaterals synapse on excitatory interneurons which excites antagonistic muscles.

53
Q

In both the stretch and inverse stretch reflex, the afferent fibers branch as they enter spinal cord and one branch ascends to contribute information to cerebellum and cerebrum about motor control and ________________________.

A

proprioception

54
Q

WHat is the purpose of flexor withdraw reflex?

A

Purpose is to withdraw limb from noxious stimulus

55
Q

In flexor withdraw reflex which muscles are excited and which are inhibited?

A

Flexors excited

Extensors inhibited

56
Q

_______________________ reflex: flexor withdrawal reflex on one side and extensor reflex on other. Good example is stepping on a tack.

A

Crossed extensor reflex

57
Q

T/F - In the crossed extensor reflex Interneurons send processes to other side of cord and excite extensors and inhibit flexors.

A

True

58
Q

If the descending pathways from the cerebral cortex and disrupted by transection of the brain stem (at level on superior and inferior colliculus) the resulting state is called decerebrate rigidity and is characterized by a tremendous increase in _________ (flexor/extensor) tone.

A

extensor

59
Q

Decerebrate rigidity results from the removal of the inhibitory influence of the brain on the brain stem and the consequent enhancement of activity in motor output from the brain stem. This is also called ______-rigidity.

A

gamma

60
Q

What is the least differentiated sensory receptor of the skin?

A

Free nerve endings

61
Q

Where are the cell bodies of free nerve endings found?

A

Dorsal roots or trigeminal ganglia

62
Q

Where are nociceptors found?

A

1) Skin, joints, muscles, and dentin of teeth
2) Wall of arteries
3) Meninges
4) Peritoneal and pleural membranes

63
Q

Where are nociceptors not found?

A

Parenchyma of internal organs (including brain)

64
Q

What are the classes of nociceptors?`

A

1) Thermal or mechanical

2) Polymodal

65
Q

Thermal or mechanical nociceptors have what fiber groups?

A

A-delta fibers

66
Q

What sensations do thermal or mechanical nociceptors relay?

A

Sharp, pricking pain (fast, first or early pain)

67
Q

What sensations do polymodal nociceptors relay?

A

Dull, aching, diffuse pain (slow, second or late pain).

68
Q

What type of fibers relay polymodal nocicpetor information?

A

C fibers (unmyelinated)

Physio Test 4 (5 decks)

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