SDL-7 Sensory Receptors Flashcards Preview

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Flashcards in SDL-7 Sensory Receptors Deck (61):
1

It takes an average of _____ms to appreciate and react to an incoming stimulus.

0.250ms

2

_______________ are receptors that respond to stimuli arising from outside the body. May be divided into two subgroups:
I. Telereceptors
II. Contact receptors

Exteroreceptors

3

______________ are receptors that detect signals originating some distance from the receptor (e.g. light detected by the eye, sound by the ear, and chemicals by the nose).

Telereceptors

4

_____________ are receptors that detect signals impinging on the external skin such as touch, pressure, heat, and cold.

Contact receptors

5

_____________ are receptors that are sensitive to signals from within the body, such as viscera, blood vessels, etc.

Interoreceptors

6

_____________ are receptors that detect signals from somatic structures which contribute to our sense of orientation and movement of the body in space (e.g. angle of limbs).

Proprioceptors

7

A specific modality of stimulus that a receptor is highly sensitive to is referred to as the ______________.

Adequate stimulus or specific energy

8

The theory that receptors are highly sensitive to one specific modality of stimulus is known as the ____________ theory.

Specific nerve energy

9

The ___________ theory states that sensation results from differing patterns of action potentials produced in a single sensory fiber.

Pattern

10

The intensity of a stimulus is coded in a single nerve fiber by the (amplitude/frequency) of action potentials.

Frequency

11

Most neurons are spontaneously active even when an action potential is not present. This rate of spontaneous activity represents a set point and is referred to as ______________.

Background frequency

12

As the strength of a stimulus increases, receptors with (higher/lower) thresholds are recruited to the synapse.

Higher

13

The absolute intensity of a stimulus involves the _______________________ and ___________________________.

I. Firing frequency of receptor nerve fibers
II. Number of receptor fibers carrying the signal

14

The initial signal that depolarizes a membrane is the ______________.

Generator potential

15

TRP receptors are non-specific, but the inward driving force for (Na+/K+/Cl-) is greater than the others, resulting in membrane depolarization.

Na+

16

_____________ is either a decrease or complete cessation of response of a receptor to a continuing or repeated stimulus.

Adaptation

17

Receptors capable of completely adapting to a stimulus are (phasic/tonic) receptors.

Phasic

18

Receptors that continue their activity as long as the stimulus is present are (phasic/tonic) receptors.

Tonic

19

____________ refers to a decrease in reflex action or to a decrease in awareness of a continuing or repeated stimulus due to decreased responsiveness of central neurons.

Habituation

20

(T/F) Habituation involves changing the strength of associated synapses which results in altered afferent input.

True

21

The ____________ of a single neuron is the area of body from which stimulation influences the neuron's discharge rate.

Receptive field

22

How is the two point discrimination test conducted?

Two point discrimination is done by touching the skin with one or two points and asking the subject to tell how many points were used. When the two points are less than a threshold distance apart, the subject will report feeling one point.

23

What is an example of the wide variety of two point discrimination thresholds in the body?

Two point discrimination threshold distance is about 1mm on the fingers, compared to about 40mm on the back.

24

The cell body of each primary somatosensory neuron is located in a (dorsal root/ventral root) ganglion of the ______________.

Dorsal root ganglion of the spinal cord

25

Primary somatosensory neurons are (unipolar/bipolar/pseudounipolar).

Pseudounipolar

26

Mechanoreceptors are exteroreceptors that detect the ___________ and/or ____________ of the skin by mechanical stimuli.

Displacement and/or velocity (rate of displacement) of skin

27

Nociceptors are exteroreceptors that detect ____________ stimuli.

Painful

28

Mechanoreceptors have afferent fibers in the ____ range.

Aβ (group II)

29

Aα(Ia) fibers are sensitive to ___________ and ___________.

I. Limb position
II. Motion

30

Aβ(II) fibers are sensitive to _________, _________, and _________.

I. Tactile
II. Pressure
III. Vibration

31

Aδ(III) fibers are sensitive to ____________ and __________.

I. Fast pain
II. Cold

32

C(IV) fibers are sensitive to _____________ and __________.

I. Slow pain
II. Warmth

33

Nociceptors have fibers in the ____ and ____ range.


C

34

(T/F) Mechanoreceptors are only present in glabrous skin.

False. Mechanoreceptors are present in both hairy and glabrous skin.

35

Merkel's disks and Ruffini's endings are examples of (nociceptors/thermoreceptors/mechanoreceptors).

Mechanoreceptors

36

_____________ are slowly adapting mechanoreceptors that respond to small displacements of the skin.

Ruffini's endings

37

____________ are mechanoreceptors that respond to indentation of the skin directly over their receptor.

Merkel's disks

38

In hairy skin, _________ and _________ detect velocity of displacement in skin.

I. Hair follicle endings
II. C-mechanoreceptors

39

In glabrous skin, ____________ detect velocity of displacement of skin.

Meissner's corpuscles

40

Meissner's corpuscles detect (low/high) frequency vibrations, typically between __-__ Hz.

Low frequency vibrations; 5-40Hz

41

A ____________ is a mechanoreceptor that detects primarily vibration of higher frequencies, between ranges of __-__Hz.

Pacinian corpuscle; 60-400Hz

42

The most sensitive of the tactile mechanoreceptors is (Merkel's disk/Pacinian corpuscle/Ruffini's endings).

Merkel's disk

43

Most unmyelinated nociceptors respond to mechanical, thermal, and chemical stimuli. Since they respond to multiple stimuli, they are referred to as ___________ receptors.

Polymodal

44

(Aching/Burning/Pricking) pain is quickly felt, transmitted by Aδ fibers, can be accurately localized, and subsides quickly.

Pricking pain

45

(Aching/Burning/Pricking) pain arises from deeper tissues and is often difficult to localize.

Aching pain

46

(Aching/Burning/Pricking) pain is slow in onset, transmitted by C fibers, less able to be precisely localized, and can persist for many seconds after removal of the stimulus.

Burning pain

47

(T/F) Pricking pain is often more difficult to endure than the other types of pain, evoking reflex increases in heart rate and respiration.

False. Burning pain is more difficult to endure and responsible for these effects.

48

A skin injury is often followed by the triple response which entails:

I. Local reddening
II. Red flare
III. Formation of a wheal on the skin

49

(T/F) The nerve fibers for both warm and cold sensation are myelinated.

False. The nerve fibers for cold sensation consist of myelinated and unmyelinated fibers, while the fibers for warm sensation are not.

50

Visceral receptors primarily respond to:

I. Stretch
II. Noxious stimuli
III. Vibration

51

Muscle stretch receptor organs (muscle spindles) contain modified skeletal muscle fibers known as _________________.

Intrafusal muscle fibers

52

Intrafusal muscle fibers are innervated near both ends by (alpha/beta/gamma) motoneurons, while extrafusal muscle fibers are innervated by (alpha/beta/gamma) motoneurons only at the midpoint of the fibers.

Intrafusal - Gamma motoneurons
Extrafusal - Alpha motoneurons

53

________________ are the larger intrafusal muscle fibers in which cell nuclei are concentrated in a central region.

Nuclear bag fibers

54

________________ are the smaller intrafusal muscle fibers in which cell nuclei are arranged in a chain.

Nuclear chain fibers

55

Intrafusal fibers have two types of sensory nerve endings: _____ and _____.

Ia and II

56

In intrafusal muscle fibers, there is(are) typically (one/two/three/many) type Ia fiber(s) per spindle.

One

57

In the muscle, intrafusal fusal fibers are arranged (in parallel/perpendicular) to extrafusal muscle fibers.

In parallel to

58

When a muscle contracts and shortens, tension on the intrafusal muscle fibers is reduced and firing decreases. How is optimal tension maintained in this situation?

When tension on intrafusal muscle fibers is decreased due to muscle contraction, gamma motor neurons that are linked with alpha motor neurons activate the intrafusal muscle fibers and cause them to shorten in proportion with the length of the contracted muscle.

59

(T/F) The sense of limb position is most likely signaled by only cutaneous receptors in the skin.

False. The best information is that limb position is signaled by a combination of skin, muscle, and joint receptors.

60

Local anesthetics, such as procaine, block __ fibers first in the transmission of an action potential.

C fibers

61

Hypoxia or pressure block __________ fibers first in the transmission of an action potential.

Large diameter fibers (A type fibers)