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MSK II > Skeletal Muscle and Nerve Tissue > Flashcards

Skeletal Muscle and Nerve Tissue Flashcards

1
Q

Function of skeletal muscle

A

voluntary movements and postural stability

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2
Q

Features of skeletal muscle

  • nuclei
  • strength, speed
  • voluntary/involuntary
  • fatiguable?
A

striated, peripheral nuclei (multinucleated)

  • strong
  • quick
  • voluntary
  • fatiguable
  • large
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3
Q

Muscle cells are made of

myofibers/myocyte/muscle fiber

A

myofibrils

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4
Q

Myofibrils are made of

A

chains of sarcomeres linked together

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5
Q

Sarcomere

  • function
  • what’s it made of
A

contractile unit of muscle made of actin and myosin myofilaments

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6
Q

Fascicle (in the muscle)

  • what is it
  • what covers it
A

group of myofibers (muscle cells); surrounded by perimysium

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7
Q

Muscle

A

a group of fascicles surrounded by epimysium

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8
Q

5 steps smallest –> largest in muscle formation

A

sarcomere –> myofibrils –> myofiber –> fascicle –> muscle

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9
Q

Epimysium

A

fascial covering over muscle

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10
Q

Perimysium

A

fascial covering over fascicles

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11
Q

Endomysium

A

fascial covering over myofibers

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12
Q

Myosin

A

makes up thick filaments; consists of myosin head and myosin tail; has two heavy chains with globular heads and two light chains

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13
Q

how is myosin connected to the Z disk

A

titin proteins

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14
Q

Actin

A

makes up thin filaments; made up of G-actin monomers (globules)

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15
Q

What determines the length of an actin filament

A

Nebulin - the “ruler”

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16
Q

Role of tropomyosin and troponin in actin filaments

A

tropomyosin strands wrap between the actin strands and troponin sits on top of the tropomyosin strands to cover myosin binding sites on actin filmanets

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17
Q

M-line

A

attachment site for myosin

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18
Q

Z-disk

A

separates sarcomeres; attachment site for actin and titin

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19
Q

H Band

A

space on either side of M-line where there is no actin; shortens as muscle contract

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20
Q

A Band

A

distance from the end of one myosin head to the head of the opposite myosin

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21
Q

I Band

A

space on either side of the Z-disk where there is no myosin

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22
Q

What events must happen for contraction to occur

A
  • Ca2+ is released from SR and binds to troponin causing conformational change, pulling tropomyosin away
  • actin binding sites are now accessible for myosin to bind
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23
Q

Role of calcium in muscle contraction

A

binds to troponin which causes a conformational change ; troponin-Ca2+ complex pulls tropomyosin away making the actin binding sites accessible to myosin heads

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24
Q

What is the sliding filament mechanism and why does it occur

A

thin filaments slide past thick filaments (actin slides past myosin) which brings the Z disks closer causing the muscle to contract

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25
Q

Do actin and myosin change in length during muscle contraction

A

no; they simply overlap each other

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26
Q

Does the A band change length during muscle contraction

A

no

27
Q

Do the H band and I band shorten during muscle contraction

A

yes

28
Q

Characteristics of type I skeletal muscle fibers

  • speed
  • strength of contraction
  • myoglobin levels
  • fatiguability
  • type of respiration
A
  • slow
  • less powerful contraction
  • abundant myoglobin
  • slow fatiguability
  • aerobic respiration (lots of mitochondria)
29
Q

Characteristics of Type IIA skeletal muscle fibers

  • speed
  • strength of contraction
  • myoglobin levels
  • fatiguability
  • type of respiration
A
  • fast
  • intermediate power of contraction
  • many myoglobin
  • intermediate fatiguability
  • aerobic respiration (lots of mitochondria)
30
Q

Characteristics of Type IIB skeletal muscle fibers

  • speed
  • strength of contraction
  • myoglobin levels
  • fatiguability
  • type of respiration
A
  • fast
  • powerful contraction
  • few myoglobin
  • rapid fatiguability
  • anaerobic respiration (few mitochondria)
31
Q

sarcolemma

A

membrane around each muscle cell

32
Q

transverse (T) tubules

A

membrane system penetrating the muscle cell to convey electrical impulses from sarcolemma into cell

33
Q

sarcoplasm

A

cytoplasm of a muscle cell

34
Q

sarcoplasmic reticulum (SR)

A

tubular system acting like the smooth ER in the muscle cell; stores calcium

35
Q

Terminal Cisternae

A

flattened sac of SR on either side of a transverse T tubule; deliver calcium

36
Q

End feet

A

connects the T tubules with SR to allow calcium release

37
Q

where do peripheral alpha motor neurons that innervate the skeletal muscle originate from

A

the anterior horn of the spinal cord

38
Q

how many nerves innervate a single muscle fiber

A

one

39
Q

how many muscles can one alpha-motor neuron innervate

A

multiple (<1)

40
Q

Neuromuscular spindle apparatus

  • action
  • components
A

A: reflexive response to prevent over-stretching of a muscle
C: extrafusal and intrafusal muscle fibers
type Ia sensory nerve fibers
alpha and gamma motor nerve fibers

41
Q

extrafusal muscle fibers in the neuromuscular spindle apparatus

A

voluntarily contract muscle

42
Q

intrafusal muscle fibers in the neuromuscular spindle apparatus

A

sense length and rate of change of the muscle

43
Q

type Ia sensory nerve fibers in the neuromuscular spindle apparatus

A

sense stretch and rate of change of intrafusal fibers; afferent innervation of intrafusal fibers

44
Q

alpha-motor neurons in the neuromuscular spindle apparatus

A

receive signals from type Ia fibers and cause extrafusal muscle fibers to contract (shorten)

45
Q

gamma-motor neurons in the neuromuscular spindle apparatus

A

receive signals from type Ia fibers and cause intrafusal muscle fibers to contract (shorten)
- continuously receiving signal from higher brain centers to stay taught and be able to detect changes

46
Q

Soma/body

A

contains all the organelles of the neuron

47
Q

nissle substance

A

abundant rough ER within the cytoplasm of the soma

48
Q

dendrite

A

receives the signal from other neurons

49
Q

axon hillock

A

connection between soma and axon; summates electrical signals received by all dendrites to transmit down axon

50
Q

axon

A

conveys electrical impulse to synapse

51
Q

synapse

A

transfers electrical impulse from the neuron to the target issue

52
Q

fascicle (in neurons)

A

group of axons

53
Q

a group of fascicles (in nervous tissue) is called a

A

nerve

54
Q

what wraps around axons

A

endoneurium

55
Q

what wraps around fascicles in a nerve

A

perineurium

56
Q

what wraps around nerve

A

epineurium

57
Q

mutipolar neuron

A

multiple dendrites and one axon

58
Q

bipolar neuron

A

a single dendrite and a single axon branching off of one cell body

59
Q

psuedounipolar neuron

A

one dendrite branch and one axon branch connected with a cell body branched off of the middle

60
Q

schwann cell

A

surrounds axons and creates the myelin sheath in the PNS; wraps around one part of the axon

61
Q

oligodendrocyte

A

surrounds axons and creates myelin sheaths in the CNS; wraps around a part of many axons

62
Q

myelin sheath

A

circumferential layers of myelin allowing for faster signal conduction velocity

63
Q

alpha-motor nerve fibers in the neuromuscular spindle apparatus provide ____

A

efferent innervation of extrafusal muscle fibers

64
Q

gamma-motor nerve fibers in the neuromuscular spindle apparatus provide ____

A

efferent innervation of intrafusal muscle fibers

MSK II (17 decks)

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