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A/P Lecture > Ch. 9 Muscular System > Flashcards

Ch. 9 Muscular System Flashcards

1
Q

Skeletal muscle structure

A
  • fasciculus
  • perimyseum
  • epimysium
  • muscular fascia
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2
Q

Fasciculus

A

bundled muscle fibers

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3
Q

Perimyseum

A

-heavy connective tissue layer that surrounds fasciculus

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4
Q

Epimysium

A

-surrounds the entire muscle (dense collagenous connective tissue)

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5
Q

Muscular fascia

A
  • superficial to the epimysium

- separates or compartmentalizes invidual muscles or groups of muscles

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6
Q

Muscle fibers

A
  • sarcolemma
  • endomysium
  • transverse tubules
  • sarcoplasmic reticulum
  • sarcoplasm
  • myofibrils
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7
Q

Sarcolemma

A

-plasma membrane

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8
Q

Endomysium

A
  • superficial, thicker layer outside of sarcolemma
  • reticular fibers
  • surrounds muscle fibers
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9
Q

T-tubules

Transverse tubules

A
  • tubelike invaginations along surface of sacrolemma

- little tunnels that enter into the cell (fiber)

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10
Q

Sarcoplasmic reticulum

A
  • modified endoplasmic reticulum

- maze of organelles inside sarcoplasm

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11
Q

Sarcoplasm

A
  • cytoplasm of muscle cell (fiber)

- muscles contain very little of this

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12
Q

Myofibrils

A
  • inside muscle fiber and sarcoplasm

- bundles of protein filaments

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13
Q

Myofilaments

A
  • the protein filaments that are inside a myofibril

- actin and myosin

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14
Q

Actin

A

-thin myofilament

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15
Q

Myosin

A

-thick myofilament

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16
Q

Sacromeres

A
  • basic unit of contraction
  • actin
  • myosin
  • titin
  • cross bridging
  • Z disks
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17
Q

Actin

A
  • structural framework of sacromere

- contains g actin, f actin, tropomyosin, troponin

18
Q

G-actin

A
  • each round molecule within actin

- contains the active site

19
Q

F-actin

A

-long chains of g-actin

20
Q

Tropomyosin

A

-double strand rope that wraps around double f-actin strand

21
Q

Troponin

A

-long portion binds to tropomyosin which opens active site so that myosin can bind

22
Q

Myosin

A
  • motor protein
  • molecules are bundled together (golf club shaped)
  • brings Z disks together (contracts)
  • the two heavy chains (rods) are wrapped around each other
  • light chains (heads) are molecules located on the globular heads
23
Q

Titin

A
  • begins at one Z disk and goes to the other Z disk
  • holds Z disk together under tension
  • largest single protein known
  • allows sacromere to extend and contract
24
Q

Z-disks

A

-actin myofilament is attached to this

25
Q

Cross-bridge

A

-where heads of myosin bind with active sites on actin

26
Q

I band

A

-includes Z disk and extends from each side of the Z disk to the ends of the myosin myofilaments

27
Q

A band

A

-extends the length of the myosin myofilaments within a sacromere

28
Q

H zone

A

-center of A band where myosin and actin do not overlap

29
Q

Membrane potentials

A
  • resting membrane potential

- action potential

30
Q

Resting membrane potential

A
  • when the inside of cell is more negatively charged (-85 mv) and the outside of the cell is positively charged
  • inside plasma membrane: high K+ concentration
  • outside plasma membrane: high Na+ concentration
  • plasma membrane is more permeable to K+ than Na+
31
Q

Action potentials

A
  • chemical signal communication

- caused by depolarization, repolarization, threshholds and propagation

32
Q

Threshold

A
  • considered point of no return

- once met, Na+ flows into cell (depolarization)

33
Q

Depolarization

A

-Na+ flow inside of cell causing the charge to become positive (+20 mv)

34
Q

Repolarization

A
  • return of membrane potential to its resting value (-85 mv)

- K+ flow out of cell

35
Q

Propagation

A
  • action potentials that travel across the plasma membrane because of stimulation
  • the spreading over membrane of voltage gates opening (think domino effect)
36
Q

Neuromuscular junction

A
  • where axon branch interdigitates with sarcolemma
  • one neuromuscular junction centrally located per muscle fiber
  • include presynaptic terminal, synaptic cleft, synaptic vesicles, neurotransmitters, acetylcholinesterase
37
Q

Presynaptic terminal

A

-each axon terminal

38
Q

Synaptic cleft

A

-space between the presynaptic terminal and sarcolemma of muscle fiber

39
Q

Postsynaptic terminal (motor end plate)

A

-muscle plasma membrane (sarcolemma) in the area of the junction

40
Q

Synaptic vesicles

A
  • storage of neurotransmitters

- spherical sacs inside presynaptic terminal

41
Q

Neurotransmitter

A
  • substance released from a presynaptic membrane that diffuses across the clet and alters the activity of the postsynaptic cell
  • acetylcholine: inside synaptic vesicles; organic molecule of acetic acid and choline
42
Q

Acetylcholinesterase

A
  • enzyme that breaks down ACH to acetic acid and choline

- breaks down ACH so that it does not accumulate in cleft causing a constant stimulus

A/P Lecture (6 decks)

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