Midterm Part 3 Functional Neuro-muscular Units Flashcards Preview

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Flashcards in Midterm Part 3 Functional Neuro-muscular Units Deck (90)
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1
Q

Order of the organization of functional skeletal muscle:

A

Muscle -> Fascicle -> Muscle Fibers -> Myofibrils -> Thick and Thin Filaments (sarcomere)

2
Q

skeletal muscle surrounded by _____ and contains _______

A

epimysium, muscle fascicles

3
Q

muscle fascicles surrounded by ______ and contains ______

A

perimysium, muscle finbers

4
Q

muscle fiber surrounded by ______ and contains _______

A

endomysium, myofibrils

5
Q

sarcomere contains ______

A

thick and thin filaments

6
Q

Neuromuscular Junction.
where is it?
what are its components?

A

site where axon and muscle fiber communicate.

Five basic components:

- motor neuron
- motor end plate
- synaptic cleft
- synaptic vesicles
- neurotransmitters
7
Q

Muscle Contraction

A

motor nerve impulses cause release of ACh from synaptic vesicles which bind to receptors on motor end plate and generate muscle contraction

8
Q

Muscle Relaxation

A

acetylcholinesterase breaks down ACh, motor neuron impulses stop, Ca moves back into sarcoplasmic reticulum, myosin and actin binding prevented

9
Q

motor unit

A

a single motor neuron and all the muscle fibers it controls

10
Q

true or false?

when a motor unit fires all the muscle fibers contract together

A

true

11
Q

true or false?

one muscle fiber may be innervated by several motor neurons

A

true

12
Q

small amount of muscle fibers makes for fine or strength control?

A

fine: extraocular muscles (20 fibers)

13
Q

Twitch

A

a single brief stimulus to a muscle that produces a quick cycle of contraction and relaxation lasting less than 1/10 sec. aka a single muscle contraction. 3 phases: latent, contraction, relaxation

14
Q

Is a single twitch contraction strong enough to do any useful work?

A

no. normal activities require more tension - sustained muscle contraction of the whole muscle!

15
Q

Treppe

A

relaxation is complete before next stimulus occurs. ea contraction a little stronger than previous. 10-20 stimuli/sec.

16
Q

Wave summation

A

temporal summation.
if a second stimulus is applied before relaxation is complete, the second contraction is greater. rapid sequence of stimuli cause twitches to fuse together – more strength of contraction.
20-40 stimuli/sec

17
Q

Tetanus

A

w higher frequency of stimulation, muscle relaxation between contractions is reduced.

18
Q

incomplete or complete tetanus?

sustained maximal contraction at peak tension

A

complete

19
Q

incomplete or complete tetanus?

produces peak tension during rapidly alternating cycles of contraction and partial relaxation

A

incomplete

20
Q

ea stimulus produces an identical twitch response. true or false?

A

true

21
Q

twitch, treppe, summation or tetanus?

ea subsequent contraction is stronger than previous until after a few stimuli, all contractions are equal.

A

treppe

22
Q

twitch, treppe, summation or tetanus?

ea stimulus arrives before the previous twitch is over.

A

wave summation. as the frequency of stimulus increase, frequency of contraction increases.

23
Q

twitch, treppe, summation or tetanus?

20-40 stimuli/sec

A

wave summation or incomplete tetanus

24
Q

twitch, treppe, summation or tetanus?

muscle fibers partially relax between contraction

A

incomplete tetanus

25
Q

twitch, treppe, summation or tetanus?

10-20 stimuli/sec

A

treppe

26
Q

twitch, treppe, summation or tetanus?

up to 10 stimuli/sec

A

twitch

27
Q

twitch, treppe, summation or tetanus?

no relaxation

A

complete tetanus

28
Q

twitch, treppe, summation or tetanus?

40-50 stimuli/sec

A

complete tetanus

29
Q

twitch, treppe, summation or tetanus?

twitches fuse into smooth, prolonged contraction

A

complete tetanus

30
Q

Sensory Neuron

A

afferent. transmit impulses from receptors to brain or spinal cord

31
Q

Motor Neuron

A

efferent. transmit impulses from brain or spinal cord to effector sites such as muscles, glands, or organs

32
Q

Interneuron

A

association neuron. transmit impulses from one neuron to another

33
Q

Which fibers are myelinated? A, B, C

A

A and B

34
Q

A, B, or C? if A, which kind?

sympathetic preganglionic

A

B

35
Q

A, B, or C? if A, which kind?

unmyelinated

A

C

36
Q

A, B, or C? if A, which kind?

fastest!

A

A alpha

37
Q

A, B, or C? if A, which kind?

smallest diameter

A

C

38
Q

A, B, or C? if A, which kind?

7ms

A

B

39
Q

A, B, or C? if A, which kind?

motor efferents

A

A alpha, A gamma

40
Q

A, B, or C? if A, which kind?

both efferents and afferents

A

A alpha

41
Q

A, B, or C? if A, which kind?

muscle spindle afferents

A

A alpha

42
Q

A, B, or C? if A, which kind?

motor efferent to muscle spindle

A

A gamma

43
Q

A, B, or C? if A, which kind?

largest diameter

A

A alpha

44
Q

A, B, or C? if A, which kind?

sympathetic postganglionic

A

C

45
Q

A, B, or C? if A, which kind?

15 ms

A

A delta

46
Q

A, B, or C? if A, which kind?

skin temperature and pain (noxious stimuli)

A

A delta

47
Q

A, B, or C? if A, which kind?

touch and pressure afferents (mechanoreceptors)

A

A beta

48
Q

A, B, or C? if A, which kind?

50ms

A

A beta

49
Q

A, B, or C? if A, which kind?

100ms

A

A alpha

50
Q

A, B, or C? if A, which kind?

pain (burning, aching, itch) 1ms

A

C

51
Q

A, B, or C? if A, which kind?

20 ms

A

A gamma

52
Q

A, B, or C? if A, which kind?

7ms

A

B

53
Q

A, B, or C? if A, which kind?

proprioceptors of skeletal muscle

A

A-alpha

54
Q

What is the basic functional unit of the nervous system?

A

Spinal Cord Reflex Arc

automatic response to stimuli wo conscious thought

55
Q

Spinal Cord Reflex Arc: 5 basic components:

A
  1. sensory receptor
  2. sensory neuron
  3. interneuron
  4. motor neuron
  5. effector organ
56
Q

Proprioception

A

the sense of position and movement of one’s own limbs and body wo using vision (somatosensory)

body & limb position, speed and direction or limb joint movement, muscle length and tension

57
Q

3 types of mechanoreceptors that detect proprioception:

A
  1. muscle spindle receptors
  2. golgi tendon organs
  3. joint kinesthetic receptors
58
Q

Where are muscle spindle receptors located?

A

fleshy part of muscle

59
Q

What are intrafusal muscle fibers?

A

modified muscle fibers enclosed in a capsule within extrafusal muscle fibers (voluntary skeletal muscle) that make up Muscle Spindle Receptors. the ends of the intrafusal fibers attach to extrafusal and are contractile.

60
Q

What do muscle spindle receptors detect?

A

rate at which the muscle fibers are stretched and how much it’s stretched

61
Q

Two types of Intrafusal Fibers (part of muscle spindle receptor)

A

nuclear bag fibers and nuclear chain fibers

62
Q

why is it called Nuclear Bag Fibers?

A

nuclei concentrated in central “bag” part of intrafusal fiber

63
Q

why is it called a Nuclear Chain Fiber?

A

nuclei are spread in a “chain-like” fashion in the center of the fiber

64
Q

Intrafusal Fibers: nuclear chain or nuclear bag?

sensitive to steady changes of length of muscle (tonic) … static

A

chain

65
Q

Intrafusal Fibers: nuclear chain or nuclear bag?

sensitive to sudden rate of change in muscle length (phasic) … dynamic

A

bag

66
Q

Intrafusal Fibers: nuclear chain or nuclear bag?

contractile ends receive input from gamma motor neurons

A

bag

67
Q

Intrafusal Fibers: nuclear chain or nuclear bag?

contractile fibers are attached to ends of nuclear bag muscle fibers

A

chain

68
Q

Intrafusal Fibers: nuclear chain or nuclear bag?

contractile fibers are attached to the extrafusal fibers

A

bag

69
Q

Intrafusal Fibers: nuclear chain or nuclear bag?

ends of fibers are striated and contractile

A

bag and chain

70
Q

Intrafusal Fibers: nuclear chain or nuclear bag?

the central non-contractile region is wrapped by sensory nerve endings that send input about length of spindle to CNS

A

bag and chain

71
Q

Two types of sensory nerve endings that wrap around non-contractile regions of intrafusal fibers:

A

primary endings type la fiber and secondary endings type ll fiber

72
Q

primary endings type la fiber or secondary endings type ll fiber?

annulospiral sensory endings

A

primary endings type la fiber

73
Q

primary endings type la fiber or secondary endings type ll fiber?

smaller diameter, conduct impulses more slowly

A

secondary endings type ll fiber

74
Q

primary endings type la fiber or secondary endings type ll fiber?

flower spray sensory endings

A

secondary endings type ll fiber

75
Q

primary endings type la fiber or secondary endings type ll fiber?

larger diameter, conduct impulses faster (100ms)

A

primary endings type la fiber

76
Q

primary endings type la fiber or secondary endings type ll fiber?

respond to rate of change in muscle fiber length

A

primary endings type la fiber

77
Q

primary endings type la fiber or secondary endings type ll fiber?

respond to overall length of muscle fiber

A

secondary endings type ll fiber

78
Q

Stretching activates the sensory neurons of the spindle. signals to brain and spinal cord. What happens next?

A

CNS activates alpha motor neurons that cause muscle extrafusal to contract resisting further stretching

79
Q

Muscle spindles sense changes in muscle _______ and _______.

A

tension and length

80
Q

What motor neurons let the brain preset the sensitivity of spindle to stretch?

A

gamma motor neurons. when brain signals gamma to fire, intrafusal fibers become tense so that little stretch is needed to stimulate sensory endings - balance reflexes. INVOLUNTARY MUSCLE CONTRACTION

81
Q

Response to stretching can be either…

A

monosynaptic spinal reflex - makes rapid adjustment to prevent fall
or
controlled by cerebellum - regulate muscle tone i.e. the steady force of a non-contracting muscle to resist stretching

82
Q

What are the encapsulated nerve endings located at the junction of tendon and muscle called? sensory neurons!

A

Golgi Tendon Organs GTOs

83
Q

GTOs detect…

GTOs prevent… how?

GOTs play a role in…

A

detect:

  • force of muscle contraction
  • tension applied to tendon

GTOs respond to slow stretch by resetting a muscles’ length and inhibiting its synergistic stabilizers while facilitating its antagonist (important!)

prevent:
- prevent a contracting muscle from applying excessive tension to tendons

how?
- produces sudden relaxation of muscles INVOLUNTARY MUSCLE RELAXATION

roles:

  • muscle tone balance
  • muscle spasm
  • tender points
84
Q

How do GTOs cause a muscle to relax? protect the tendons and muscles!

A

only intense stretch! -> lb sensory neurons from GTOs stimulated –> to spinal cord to synapse w inhibitory interneurons –> inhibitory neurotransmitters released –> alpha motor neurons inhibited

85
Q

GTO: Dynamic Response vs Static Response

A

sudden increase in muscle tension causes a decrease in muscle tone

via involuntary muscular relaxation, quick stretch = Dynamic

postural tone = Static

86
Q

Where are joint kinesthetic receptors located?

What do they detect?

3 types?

A
  • located in and around synovial joint capsules.
  • detect direction of movement, acceleration/deceleration, pressure of joint, excessive joint strain, postural changes, input from skin receptors - ruffini and merkel’s discs
  • 3 types: Pacinian corpuscles, Ruffini corpuscles, Free nerve endings
87
Q

Which type of Joint Kinesthetic Receptor: Pacinian, Ruffini, or Free Nerve Endings?

  • located in CT and synovial joint capsules
  • responds to rapid pressure changes, stretch, acceleration and deceleration of joint movement
A

Pacinian Corpuscles

88
Q

Which type of Joint Kinesthetic Receptor: Pacinian, Ruffini, or Free Nerve Endings?

  • located in most body tissues
  • respond to rapid and sustained pressure
A

Free Nerve Endings

89
Q

Which type of Joint Kinesthetic Receptor: Pacinian, Ruffini, or Free Nerve Endings?

  • located in synovial capsules and ligaments
  • respond to deep rapid, sustained pressure, lateral stretch
A

Ruffini Corpuscles

90
Q

Which type of Joint Kinesthetic Receptor: Pacinian, Ruffini, or Free Nerve Endings?

  • detects changes in joint angles
  • ligament receptors adjust muscle tone
A

Ruffini Corpuscles