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MSK II > Skeletal Muscle and Nerve Tissue > Flashcards

Skeletal Muscle and Nerve Tissue Flashcards

(64 cards)

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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
Do actin and myosin change in length during muscle contraction
no; they simply overlap each other
26
Does the A band change length during muscle contraction
no
27
Do the H band and I band shorten during muscle contraction
yes
28
Characteristics of type I skeletal muscle fibers - speed - strength of contraction - myoglobin levels - fatiguability - type of respiration
- slow - less powerful contraction - abundant myoglobin - slow fatiguability - aerobic respiration (lots of mitochondria)
29
Characteristics of Type IIA skeletal muscle fibers - speed - strength of contraction - myoglobin levels - fatiguability - type of respiration
- fast - intermediate power of contraction - many myoglobin - intermediate fatiguability - aerobic respiration (lots of mitochondria)
30
Characteristics of Type IIB skeletal muscle fibers - speed - strength of contraction - myoglobin levels - fatiguability - type of respiration
- fast - powerful contraction - few myoglobin - rapid fatiguability - anaerobic respiration (few mitochondria)
31
sarcolemma
membrane around each muscle cell
32
transverse (T) tubules
membrane system penetrating the muscle cell to convey electrical impulses from sarcolemma into cell
33
sarcoplasm
cytoplasm of a muscle cell
34
sarcoplasmic reticulum (SR)
tubular system acting like the smooth ER in the muscle cell; stores calcium
35
Terminal Cisternae
flattened sac of SR on either side of a transverse T tubule; deliver calcium
36
End feet
connects the T tubules with SR to allow calcium release
37
where do peripheral alpha motor neurons that innervate the skeletal muscle originate from
the anterior horn of the spinal cord
38
how many nerves innervate a single muscle fiber
one
39
how many muscles can one alpha-motor neuron innervate
multiple (<1)
40
Neuromuscular spindle apparatus - action - components
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
extrafusal muscle fibers in the neuromuscular spindle apparatus
voluntarily contract muscle
42
intrafusal muscle fibers in the neuromuscular spindle apparatus
sense length and rate of change of the muscle
43
type Ia sensory nerve fibers in the neuromuscular spindle apparatus
sense stretch and rate of change of intrafusal fibers; afferent innervation of intrafusal fibers
44
alpha-motor neurons in the neuromuscular spindle apparatus
receive signals from type Ia fibers and cause *extrafusal* muscle fibers to contract (shorten)
45
gamma-motor neurons in the neuromuscular spindle apparatus
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
Soma/body
contains all the organelles of the neuron
47
nissle substance
abundant rough ER within the cytoplasm of the soma
48
dendrite
receives the signal from other neurons
49
axon hillock
connection between soma and axon; summates electrical signals received by all dendrites to transmit down axon
50
axon
conveys electrical impulse to synapse
51
synapse
transfers electrical impulse from the neuron to the target issue
52
fascicle (in neurons)
group of axons
53
a group of fascicles (in nervous tissue) is called a
nerve
54
what wraps around axons
endoneurium
55
what wraps around fascicles in a nerve
perineurium
56
what wraps around nerve
epineurium
57
mutipolar neuron
multiple dendrites and one axon
58
bipolar neuron
a single dendrite and a single axon branching off of one cell body
59
psuedounipolar neuron
one dendrite branch and one axon branch connected with a cell body branched off of the middle
60
schwann cell
surrounds axons and creates the myelin sheath in the *PNS*; wraps around one part of the axon
61
oligodendrocyte
surrounds axons and creates myelin sheaths in the *CNS*; wraps around a part of many axons
62
myelin sheath
circumferential layers of myelin allowing for faster signal conduction velocity
63
alpha-motor nerve fibers in the neuromuscular spindle apparatus provide ____
efferent innervation of extrafusal muscle fibers
64
gamma-motor nerve fibers in the neuromuscular spindle apparatus provide ____
efferent innervation of intrafusal muscle fibers

MSK II (17 decks)

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