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Anatomy And Physiology 1 > Chpt. 9.1 - 9.6 Skeletal Muscle, Smooth Muscle & Cardiac Muscle > Flashcards

Chpt. 9.1 - 9.6 Skeletal Muscle, Smooth Muscle & Cardiac Muscle Flashcards

1
Q

Muscle

A
  • A bundle of fascicles

- Surrounded by epimysium and fascia

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2
Q

Fascicle

A
  • A bundle of muscle fibers within a muscle

- Surrounded by perimysium

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3
Q

Muscle fiber

A
  • A single multinucleated muscle cell

- -Surrounded by endomysium

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4
Q

Myofibril

A

-Thick and thin filaments in repeating pattern (sarcomeres)

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5
Q

I-Bands

A
  • Light bands composed of thin actin filaments held together by attachments to Z-lines
  • Narrows during contraction
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6
Q

A-bands

A
  • Dark bands composed of thick myosin filaments overlapping thin actin filaments (length = length of myosin filament)
  • Does not change size during contraction
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7
Q

H-zone

A
  • consists of only thick myosin filaments

- Narrows during contraction

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8
Q

M-line

A

-consists of proteins that help hold the thick myosin filaments in place

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9
Q

Z-line

A
  • consists of thin actin filaments

- lines move closer together during contraction, shortening the sarcomere

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10
Q

Stimulus for Contraction

A

1) Action potential reaches ACh vesicles in distal end of axon
2) Vesicles release acetylcholine into the synaptic cleft
3) Acetylcholine molecules bind to protein-specific receptors in the muscle fiber membrane, increasing membrane permeability to sodium and potassium ions, opens more sodium channels on sarcolemma
4) Action potential conducted spreads throughout the muscle cell which triggers the release of calcium ions from the SR, contraction can occur

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11
Q

Muscle Contraction

A

1) Ca2+ binds to troponin exposing binding sites on actin molecules
2) Myosin heads bind to actin
3) ADP+P release from myosin and power stroke pulls actin filaments
4) ATPs forms, breaking connection to actin
5) ATP splits into ADP+P, cocks myosin heads and store energy for next power stroke

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12
Q

Muscle Relaxation

A

1) Action potential stops
2) Acetylcholesterase decomposes remaining ACh in synaptic cleft
3) Calcium ions move back into SR

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13
Q

Summation

A

Force of individual twitches combines and increases in frequency, before relaxing

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14
Q

Tetanus

A

Forceful, sustained contraction that lacks partial relaxation

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15
Q

Recruitment

A

Increase in number of activated motor units, recruitment continues until the intensity of stimulation increases

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16
Q

Isotonic contractions

A

concentric - muscle contracts with force greaer than resistance (shortens)

eccentric - muscle contracts with force less than resistance and lengthens

17
Q

Isometric contractions

A

Tension with muscle increases, but wall does not move

18
Q

Slow-twitch muscle fiber

A
  • red fibers (contain myoglobin)
  • contracts slower
  • good blood supply
  • lots of mitochondria
  • high respiratory capacity
  • fatigue-resistant (primarily oxidative)
19
Q

Fast-twitch muscle fiber

A
  • white fibers (less myoglobin)
  • contracts rapidly
  • poorer blood supply
  • fewer mitochondria
  • reduced respiratory capacity
  • more extensive SR & faster ATPase
  • fatigue easily (primarily glycolytic)
20
Q

Intermediate muscle fiber

A
  • white fiber
  • contracts rapidly
  • fatigue-resistant (intermediate oxidative capacity)
21
Q

Oxygen debt

A
  • Oxygen low due to strenuous activity
  • Caused by anaerobic respiration
  • Amount of oxygen needed to convert lactic acid to glucose, resynthesize ATP & creatine phosphate
  • Amount of oxygen needed to restore blood and tissue oxygen levels to pre-exercise levels
22
Q

Smooth Muscle Characteristics

A
  • shorter fibers than skeletal
  • single, centrally located nuclei
  • lack striations and transverse tubules
  • SR not well-developed
23
Q

Multiunit Smooth Muscle

A
  • cells less well-organized and function independently
  • contract only by stimulation by neurons or hormones
  • ex: iris of the eye and large blood vessels
24
Q

Visceral Smooth Muscle

A
  • composed of sheets of spindle-shaped cells held together by gap junctions
  • respond as single unit
  • peristalsis (wavelike motion) due conduction of impulse by nearby cells and rhythmicity
25
Q

Smooth Muscle Contraction

A

Similar to skeletal:

  • actin and myosin
  • both use Ca2+ and ATP
  • both are triggered by membrane impulsese

Different to skeletal:

  • lacks troponin, has calmodulin
  • uses acetylcholine AND norepinephrine
  • hormones can stimulate/inhibit smooth muscle
  • more resistant to fatigue
  • change length w/o changing tautness
26
Q

Cardiac Muscle Characteristics

A
  • found in the walls of the heart
  • striated, uninucleated
  • joined together by intercalated discs
  • fibers branch and join together at these discs
  • contract as unit
  • self-exciting and has rhythmicity
  • long refractory period
  • no sustained or tetanic contractions
27
Q

agonist

A

causes an action

28
Q

antagonist

A

works against the action

Anatomy And Physiology 1 (12 decks)

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