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Anatamy And Physiology > Muscle System > Flashcards

Muscle System Flashcards

1
Q

Functions of the muscular system

A
  • Movement
  • Tone
  • Protection
  • Control of Openings
  • Body Temperature
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2
Q

Functions of the muscular system- movement

A

As muscle
contracts, it
pulls bones.

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3
Q

Functions of the muscular system-tone

A

Even when not
moving, some muscle
units are always
contracted.

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4
Q

Functions of the muscular system- protection

A

Abdominal organs
are only
protected by
muscle.

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5
Q

Functions of the muscular system- control of opening

A

Sphincters guard the
openings of the
digestive and urinary
systems.

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6
Q

Functions of the muscular system- body temperature

A

Muscle contractions
generate heat.

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7
Q

Muscles

A
  • Muscle is made of a hierarchy of elongated
    bundles.
    ▪ Fascicles are the largest bundles and can be
    seen with the naked eye.
  • Each layer of bundles is covered with a
    type of fascia
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8
Q

Fascia

A

(Def) connective tissue that
separates it from other tissues
- All layers of fascia
combine to form tendons
or aponeuroses.
▫ Tendons are
cylindrical and
attach to bones.
▫ Aponeuroses are flat
and attach to bones
or other muscles.

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9
Q

Tendon

A

(Def) are cylindrical and
attach to bones.
- A ruptured tendon will detach a muscle from one of its bones, rendering it unusable.

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10
Q

(the entire organ) is covered with
Epimysium

A

Muscle

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11
Q

(groups of skeletal muscle fibers) are covered with Perimysium

A

Fascicles

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12
Q

(highly specialized muscle cells) are covered with
Endomysium

A

Muscle fibers

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13
Q

(muscle cell threads made of myofilaments: actin &
myosin) are covered with Sarcoplasmic Reticulum

A

Myofibrils

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14
Q

Organization of skeletal muscles

A

Muscle- belly
|
Fascicle- a bundle of muscle fibers
|
Muscle fiber- muscle cell
|
Sarcomere- units of myofibrils responsible for the striated appearance
|
Myofibrils- structures that make up a muscle fiber
|
Myofilament- protein filaments that make up a sarcomere
- myosin- thick filaments
- actin- thin filaments

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15
Q

Skeletal muscle fibers

A

▫ Very long (up to 30cm).
▫ Multinucleate: Multiple nuclei per cell.
▫ Amitotic: Unable to divide

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16
Q

Special structures within muscle fibers include

A
  • Sarcolemma
  • M itochondria
  • Sarcoplasmic reticulum
  • Myofibrils
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17
Q

Sarcolemma

A

Cell membrane;
contain t-
tubules that
penetrate
through the
center of the
cell.

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18
Q

Mitochondria

A

Generate ATP.

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19
Q

Sarcoplasmic
Reticulum

A

Type of smooth
ER that stores
calcium ions
that trigger
contraction.

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20
Q

Myofibrils

A

Rod-shaped
organelles with
contractile proteins
called actin and
myosin.

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21
Q

sarcomere

A
  • is the contractile unit of
    myofibrils, with two types of protein
    filaments:
    ▫ Actin, which are thinner and lighter.
    ▫ Myosin, which are thicker and darker.
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22
Q

Myosin and actin

A
  • Myosin and actin
    overlap somewhat
    in the sarcomere
  • Myosin filaments
    have heads
    (extensions) that
    can ‘grab’ onto
    actin forming a
    crossbridge
  • During muscle contraction, “heads” on the
    myosin filaments attach to actin filaments,
    pulling them inwards.
  • When this happens across
    the entire muscle, it
    contracts and shortens,
    forming a muscle belly.
  • Myosin will only pull actin in the presence
    of ATP.
    ▫ Constant energy input is required for
    movement.
23
Q

Sliding Filament

A

a muscle
contracts when the thin filament in the
muscle fiber slides over the thick filament
- Activated by ATP and calcium (Ca+) ions

24
Q

The Sliding Filament Theory of Muscle Contraction

A

1) An influx of Ca2+ causes thick myosin filaments to form
crossbridges with the thin actin filament by exposing the
binding site on actin

2) The crossbridges change shape as it pulls
on filaments which slides towards the center
of the sacromere in the power stroke
- The distance between the Z line decreases,
shortening the muscle.

3) The crossbridges detach from the actin filament when ATP bonds to myosin head.

4) The myosin head gets ready to bond to actin again
using ATP energy
- The cycle is repeated on another site of actin filament using the
stored ATP energy

25
Q

Rigor mortis

A
  • is the stiffening of muscles
    after death due to the lack of ATP production.
  • Lasts 1-4 days, until muscle fibers break
    down.
26
Q

Neuromuscular Coordination

A

Muscle tissue is not able
to contract without the
support of one or more
nerves
• The collective
relationship between the
muscular and nervous
systems is called the
neuromuscular system

27
Q

motor neuron

A

the type of nerve cell that
stimulates a muscle.
• This occurs across a
neuromuscular junction

28
Q

Transmission of Nerve Impulse to Muscle

A

-Step 1: Nerve releases a
neurotransmitter (acetylcholine)
-Step 2: Neurotransmitter causes the
muscle cell membrane gates to open
-Step 3: Ions (Na+ & K+) exchange places
causing the sarcoplasmic reticulum to
release Ca2+
-Step 4: This release of Ca+ starts the
muscle contraction as the actin filaments
slide past the myosin filaments

29
Q

steps of Muscle Contraction

A

▪ A signal is received from a motor neuron.
▪ Signal is sent to every myofibril in the
muscle fiber simultaneously through t-
tubules.
▪ The sarcoplasmic reticulum releases
calcium ions (Ca2+).
▪ The calcium influx stimulates the myosin
filaments to attach to the actin
filaments.
▪ Myosin attaches to ATP, releasing actin.

30
Q

Skeletal muscles

A

must be
stimulated by a
nerve (motor
neuron) to
contract

31
Q

twitch

A

is a single contraction
relaxation cycle of
a motor unit.

32
Q

Motor units

A

are
motor neurons
and all their
associated
muscle fibers.

33
Q

Summation

A

occurs when two twitches combine
into a more powerful movement.
▫ Second stimulus is received before the
motor unit completes relaxation.

34
Q

Tetanus

A

occurs when the frequency of
stimulation is so high that the relaxation
phase disappears.
▫ Maximum muscle tension.

35
Q

ATP

A

is broken down into ADP to provide an energy source for muscle contraction.
▫ ATP is unstable, so cells only have enough available to last a few seconds.

36
Q

Creatine phosphate

A

can be broken down to
release high energy
phosphates,
recharging ATP.
▫ Muscles store 8-10
seconds worth

37
Q

Glycolysis

A
  • Happens in the
    cytosol.
  • Generates 2 ATP
    per glucose
    molecule.
  • Anaerobic: no
    oxygen required.
38
Q

Aerobic Respiration

A
  • Happens in the
    mitochondria.
  • Generates 34 ATP
    per glucose
    molecule.
  • Aerobic: oxygen is
    required.
  • if oxygen is abundant
39
Q

Lactic Acid Fermentation

A
  • Happens in the
    cytosol.
  • Allows glycolysis
    to continue.
  • Anaerobic: no
    oxygen needed
  • if oxygen is deficient
40
Q

Glucose

A

▪ Glucose is
regenerated by
breaking down
glycogen, a
polysaccharide.
▫ Stored in the
liver and muscles.

41
Q

Fatigue arises from two conditions that limit ATP

A
  • Insufficient Oxygen
  • Insufficient Glucose
42
Q

Insufficient Glucose

A
  • Glycogen storage is
    completely used up.
  • Blood glucose levels
    become too low.
  • “Hitting the wall”
43
Q

Insufficient Oxygen

A
  • Muscles must use
    glycolysis and
    lactic acid
    fermentation.
  • Lactic acid
    irritates muscles,
    causing soreness.
  • “Out of breath”
44
Q

Aerobic Exercise

A
  • Improved oxygen
    intake, lactate
    clearance, and
    glycogen storage.
  • Improved
    endurance.
  • Jogging,
    distance swimming
45
Q

Anaerobic Exercise

A
  • Muscle fiber size
    increases.
  • Improved strength.
  • Weightlifting,
    sprinting
46
Q

Fast Twitch

A
  • Reach peak
    tension quickly.
  • Densely packed
    with myofibrils.
  • Fewer
    mitochondria.
  • Produce more
    force, but tire
    quickly
47
Q

Slow Twitch

A
  • Reach peak tension more slowly.
  • More mitochondria.
  • Contains myoglobin
    that stores
    oxygen.
  • Produces less
    force, but better
    endurance.
48
Q

Anabolic steroids

A
  • mimic testosterone,
    increasing protein
    synthesis in muscle
    fibers.
    ▪ Side effects:
    ▫ Increase in blood
    cholesterol
    ▫ Acne ▫ High blood pressure ▫ Testicular atrophy ▫ Emergence of male
    characteristics in women
49
Q

Muscular
dystrophy

A

causes the
degeneration
and
atrophy of
muscle.

50
Q

Muscle spasms

A
  • are involuntary
    contractions of
    single muscles.
    ▫ Painful spasms are
    called cramps

▪ Caused by overuse,
lack of electrolytes,
dehydration, etc.

51
Q

Polio

A

a virus that
destroys motor
neurons, causing
paralysis.

52
Q

Amyotrophic Lateral
Sclerosis (ALS)

A

is a genetic disease that
damages motor neurons,
causing gradual muscle
atrophy.

53
Q

Fibromyalgia

A

causes pain
throughout the
muscle fascia
–
epimysium,
perimysium,
endomysium, and
tendons.

Anatamy And Physiology (14 decks)

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