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Anatomy > Muscle Test > Flashcards

Muscle Test Flashcards

1
Q

Define myology

A

study of muscles

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2
Q

Know the 3 types of muscle tissue and all of their characteristics

A
  • Cardiac- found in heart, has some striations, involuntary, pumps blood, able to regenerate sometimes
  • Smooth- not striated, involuntary, found inside hollow organs and blood vessels, high capability of regeneration, function depends on location
  • Skeletal- most striated, voluntary, attach to bones, function- help with movement, have limited regeneration capacity (because most cells are post mitotic)
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3
Q

Total Body Weight

A

Total body weight: 40-50%

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4
Q

5 functions

A

Produce heat by contractions
Produces movement
Regulates organ volume
Stabilizes body position
Moves substances through body

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5
Q

Know what type of tissue makes up muscle.

A

Connective tissue, areolar CT, adipose CT, dense irregular CT, dense regular CT (in collagen fibers)

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6
Q

Define all parts of a muscle and know the tissues that make them up if we discussed it. Ex: fascia, epimysium, etc.

A
  • Fascia- a sheet of CT found beneath the skin and around muscles and organs
    • Superficial: right under the skin: made up of areolar and adipose CT
    • Deep: holds muscle together: separates into functional groups (bundles): dense irregular CT
  • Epimysium- covers entire muscle cell
  • Perimysium- surrounds bundles of 10-100 muscle fibers called fascicles
  • Endomysium- wraps around each individual muscle fiber
  • Tendon- connects muscle to bone
  • Collagen fiber: cord of dense reg. CT
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7
Q

Muscle fiber

A

100s to 1000s make up skeletal muscles, arranged parallel to each other

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8
Q

Sarcolemma

A

plasma membrane around each muscle fiber

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9
Q

Transverse (T) tubules-

A

tunnel-like extensions of sarcolemma that pass through muscle fibers from side to side

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10
Q

Sarcoplasm

A

muscle fibers cytoplasm, contains many mitochondria for ATP during muscle contractions

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11
Q

Sarcoplasmic reticulum

A

network of fluid filled membrane enclosed tubules
- Store Ca ions for contraction
- Similar to smooth ER

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12
Q

Myoglobin

A

red pigment in sarcoplasm
- Gives color to skeletal muscle
- Stores O2 until used by mitochondria

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13
Q

Myofibrils

A

cylinder structure found in inside muscle fibers

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14
Q

Filaments

A

overlap in specific patterns to form sarcomeres

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15
Q

Sarcomere

A

basic functional unit of striated muscle fiber

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16
Q

Z disc

A

zig zagging zones on dense proteins; separates sarcomeres from each other

16
Q

A Band

A

dark area in sarcomere

17
Q

H zone-

A

narrow part of thick filament

18
Q

I band

A

light are on each side of A band

19
Q

Thick filaments

A

made up of protein myosin, looks like 2 golf clubs twisted together, myosin heads and tails

20
Q

Thin filaments

A

made up of protein actin; actin molecules join to form an actin filament- twisted into a helix
- Brown spots: myosin binding site
- 2 other proteins- tropomyosin and troponin: cover up myosin binding sites when muscle relaxes

21
Q

Know what a motor unit is and everything that makes it up.

A
  • Motor unit- 1 neuron + muscle cells stimulated
    • Axon- extension of neuron
    • Axon terminal- end of axon
    • Synaptic cleft- space between neuron and muscle fiber
    • Acetylcholine (ACh)- neurotransmitter
    • Motor neuron- 1 nerve cell
22
Q

Define neuromuscular junction and everything that makes it up.

A
  • Neuromuscular junction- where axon terminal meets muscle fiber
    - Consists of axon terminals resting in folds of sarcolemma of a muscle fiber
    • Presynaptic terminal- motor neuron axon terminal
      - Postsynaptic membrane/motor end plate- sarcolemma of muscle fiber that’s stimulated
    • Synaptic cleft- between presynaptic terminal and muscle fiber
23
Q

Define cross-bridge

A
  • when myosin heads bind to active sites on actin
  • Cross-bridge cycling- during a single contraction, each myosin molecule undergoes repeated cycles of:
    • Cross-bridge formation
    • Movement (actin slides over myosin myofilament)
    • Release
    • Return to original position
24
Q

Explain how the sliding filament model works

A

During contraction, thin filaments slide past thick ones
Myosin heads latch onto active sites– called cross bridge
Attachments made and broken propel the thin filaments which then slide

25
Q
A
26
Q

Explain the roles of Calcium and acetylcholine in muscle contraction and relaxation

A

Calcium
Ca2+ moves back into sarcoplasmic reticulum by active transport
Requires energy
Ca2+ moves away from troponin- tropomyosin complex
Complex re-establishes its position and blocks active sites of actin molecule

26
Q

Know what an action potential is

A

Action potential- electrical signals
Nervous system controls muscle contractions through action potentials
Travel from brain/spinal cord along axons to stimulate muscle fibers

26
Q

Explain how depolarization and repolarization work, including hyperpolarization.

A
  • Depolarization- inside of plasma membrane becomes more positive
    • Na+ gates open
    • Na+ enters cell
    • If change in charge reachers threshold, action potential triggered
  • Repolarization- return of resting membrane potential
    • Na+ gates close
    • Membrane potential drops lower than its original resting potential then rebounds
      - This is because K+ gates open, K+ leaks out, but then Na/K pump restores resting membrane potential
26
Q

The the steps in muscle contraction

A
  1. Action potential travels down sarcolemma along T-tubules
  2. Calcium released from sarcoplasmic reticulum
  3. Calcium binds to troponin which changes shape then myosin binding sites are exposed on actin
    4.Myosin cross– bridge forms with actin
    5.Myosin head pivots and pulls actin filament to m line
    6.ATP attaches to myosin and cross bridge detaches
    7.Myosin can be reactivated (keep contracting)
26
Q

Be able to explain the membrane potential difference in a cell

A

Resting membrane potential- membrane voltage difference across plasma membrane
Inside cell is more negative, accumulation of large protein molecules; more K+ on inside than outside; some K+ leaks out (-70 to -90 mV)
Outside cell more positive; more K+
Na+/K+ pump maintains this ion difference: pumps out Na+, moves in K+
Must exist for action potential to occur

26
Q

Know the steps of the excitation of a muscle cell

A
  1. Activation potential travels down axon and arrives at NMJ
  2. Release of acetylcholine into synaptic cleft
  3. ACh diffuses across cleft and attaches to ACh receptors on sarcolemma of muscle fibers
  4. Rush of Na+ into sarcoplasm produces action potential in sarcolemma
  5. ACh broken down
26
Q

Explain why a muscle relaxes.

A
  • Ca2+ moves back to sarcoplasmic reticulum by active transport (requires energy)
  • Ca2+ moves away from troponin to

Anatomy (4 decks)

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