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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
Rigor mortis
- is the stiffening of muscles after death due to the lack of ATP production. - Lasts 1-4 days, until muscle fibers break down.
26
Neuromuscular Coordination
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
motor neuron
the type of nerve cell that stimulates a muscle. • This occurs across a neuromuscular junction
28
Transmission of Nerve Impulse to Muscle
-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
steps of Muscle Contraction
▪ 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
Skeletal muscles
must be stimulated by a nerve (motor neuron) to contract
31
twitch
is a single contraction relaxation cycle of a motor unit.
32
Motor units
are motor neurons and all their associated muscle fibers.
33
Summation
occurs when two twitches combine into a more powerful movement. ▫ Second stimulus is received before the motor unit completes relaxation.
34
Tetanus
occurs when the frequency of stimulation is so high that the relaxation phase disappears. ▫ Maximum muscle tension.
35
ATP
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
Creatine phosphate
can be broken down to release high energy phosphates, recharging ATP. ▫ Muscles store 8-10 seconds worth
37
Glycolysis
- Happens in the cytosol. - Generates 2 ATP per glucose molecule. - Anaerobic: no oxygen required.
38
Aerobic Respiration
- Happens in the mitochondria. - Generates 34 ATP per glucose molecule. - Aerobic: oxygen is required. - if oxygen is abundant
39
Lactic Acid Fermentation
- Happens in the cytosol. - Allows glycolysis to continue. - Anaerobic: no oxygen needed - if oxygen is deficient
40
Glucose
▪ Glucose is regenerated by breaking down glycogen, a polysaccharide. ▫ Stored in the liver and muscles.
41
Fatigue arises from two conditions that limit ATP
- Insufficient Oxygen - Insufficient Glucose
42
Insufficient Glucose
- Glycogen storage is completely used up. - Blood glucose levels become too low. - “Hitting the wall”
43
Insufficient Oxygen
- Muscles must use glycolysis and lactic acid fermentation. - Lactic acid irritates muscles, causing soreness. - “Out of breath"
44
Aerobic Exercise
- Improved oxygen intake, lactate clearance, and glycogen storage. - Improved endurance. - Jogging, distance swimming
45
Anaerobic Exercise
- Muscle fiber size increases. - Improved strength. - Weightlifting, sprinting
46
Fast Twitch
- Reach peak tension quickly. - Densely packed with myofibrils. - Fewer mitochondria. - Produce more force, but tire quickly
47
Slow Twitch
- Reach peak tension more slowly. - More mitochondria. - Contains myoglobin that stores oxygen. - Produces less force, but better endurance.
48
Anabolic steroids
- 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
Muscular dystrophy
causes the degeneration and atrophy of muscle.
50
Muscle spasms
- are involuntary contractions of single muscles. ▫ Painful spasms are called cramps ▪ Caused by overuse, lack of electrolytes, dehydration, etc.
51
Polio
a virus that destroys motor neurons, causing paralysis.
52
Amyotrophic Lateral Sclerosis (ALS)
is a genetic disease that damages motor neurons, causing gradual muscle atrophy.
53
Fibromyalgia
causes pain throughout the muscle fascia – epimysium, perimysium, endomysium, and tendons.

Anatamy And Physiology (14 decks)

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