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Anatomy & Physiology > Muscles > Flashcards

Muscles Flashcards

1
Q

What are the three types of muscle tissue?

A
  • Skeletal
  • Cardiac
  • Smooth
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2
Q

Define:

Excitability

A

Plasma membranes can change electrical states and send action potential along membrane length

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3
Q

What are the three properties of muscle tissue?

A
  • Elasticity
  • Extensibility
  • Contractility
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4
Q

Define:

Elasticity

A

Allows muscle to return to original length when relaxed due to elastic fibers

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5
Q

Define:

Extensibility

A

Muscle tissue can stretch or extend

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6
Q

Define:

Contractility

A

Allows muscle tissue to pull on its attachment points and shorten with force

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7
Q

Define:

Epimysium

A

Outer sheath of dense, irregular connective tissue covering muscle

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8
Q

Define:

Fascicle

A

Bundles of muscle fibers

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9
Q

Define:

Sarcomere

A

Functional unit of skeletal muscle

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10
Q

What are the two key proteins that make up contractile machinery?

A

Actin and myosin

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11
Q

What happens to sarcomere structure when muscle contracts?

A
  • A band stays the same.
  • I band becomes smaller.
  • Z-discs come closer together.
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12
Q

Define:

Myosin

A
  • Thick filament
  • Composed of globular head and long tail
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13
Q

Define:

Actin

A
  • Thin filament
  • Double helix, “string of pearls”
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14
Q

Define:

Troponin

A

Globular molecule attached at regular intervals to tropomyosin

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15
Q

Define:

Tropomyosin

A

Long polypeptide chain that lies in grooves between actin helices

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16
Q

What is the force generated by actin-myosin interaction proportional to?

A

The number of myosin heads that can interact with thin filament

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17
Q

What is the excitation portion of “excitation-contraction coupling”?

A

Propagation of action potential along sarcolemma

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18
Q

Where does the action potential travel from the sarcolemma to reach the sarcoplasmic reticulum?

A

The transverse-tubules (T-tubules)

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19
Q

What ion initiates muscle fiber contraction?

A

Calcium

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20
Q

What are the steps involved in cross-bridge cycling?

A
  1. ATP binds with myosin head, forming ADP and Pi with calcium binding to troponin.
  2. Myosin binds with exposed actin binding site, generating force.
  3. ADP and Pi released from myosin head.
  4. Another ATP binds to myosin.
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21
Q

How does muscle relaxation occur?

A
  • Signaling from motor neuron ends and sarcolemma repolarizes
  • Muscle runs out of ATP and becomes fatigued
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22
Q

Define:

Sliding filament theory of muscle contraction

A

Shortening of sarcomere results from relative movement of actin and myosin filaments past each other while each filament retains original length

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23
Q

Define:

Creatine phosphate

A

Created when resting muscle transfers energy from excess ATP to creatine to produce ADP and creatine phosphate

24
Q

What are the three types of muscle contraction?

A
  • Isotonic
  • Isometric
  • Isokinetic
25
Q

Define:

Isotonic contraction

A

Tension in muscle stays constant and load is moved while length of muscle changes

26
Q

Define:

Concentric contraction

A

Muscle shortens to move load

27
Q

Define:

Eccentric contraction

A

Muscle lengthens while resisting load

28
Q

Define:

Isometric contraction

A

Muscle produces tension without changing length and not moving load

29
Q

Define:

Isokinetic contraction

A

Muscle contraction and resulting change in joint angle at constant speed

30
Q

How is the number of muscle fibers in a motor unit determined?

A

By degree of control required by muscle

Fine movement muscles have fewer muscle fibers per unit while coarse movement muscles have many muscle fibers per unit.

31
Q

Define:

Myogram

A

Measures muscle activation and contraction

32
Q

What are the three phases of a twitch?

A
  1. Latent period
  2. Contraction period
  3. Relaxation phase
33
Q

Define:

Latent period

A

When action potential is propagated along sarcolemma and calcium ions released from sarcoplasmic reticulum

34
Q

Define:

Contraction phase

A
  • Calcium ions bind to troponin
  • Tropomyosin moves away from actin bindinng sites, causing cross-bridges to form
35
Q

Define:

Relaxation phase

A

Tension decreases as contraction stops with calcium ions pumped out of sarcoplasm into sarcoplasmic reticulum

36
Q

Define:

Muscle tone

A

Small amount of contraction in skeletal muscles

37
Q

Define:

Hypotonia

A

Absence of low-level contractions that cause muscle tone

38
Q

Define:

Hypertonia

A

Excessive muscle tone and excessive reflex responses (hyperreflexia)

39
Q

Define:

Slow oxidative, type I muscle fiber

A
  • Contract relatively slowly and use aerobic respiration to produce ATP
40
Q

Define:

Fast oxidative, type IIa muscle fiber

A

Have fast contractions and primarly use aerobic respiration but can also use anaerobic respiration

41
Q

Define:

Fast glycolytic, type IIb muscle fiber

A

Have relatively fast contractions and use glycolysis to produce ATP

42
Q

Define:

Gap junction

A

Forms channels between adjacent fibers allowing depolarizing current from cations to flow from one muscle cell to next

43
Q

What is the function of electric coupling

A

Quick transmission of action potentials and coordinate heart contractions

44
Q

Define:

Syncytium

A

Functional unit of contraction created by network of electrically connected cardiac muscle cells

45
Q

Define:

Desmosomes

A

Cell structure anchoring ends of cardiac muscle fibers together

46
Q

What is the function of pacemaker cells?

A

Control heart contractions in response to signals from autonomic nervous system to speed up/slow down heart rate

47
Q

Define:

Autorhythmicity

A

The ability to depolarize and fire action potentials independently

48
Q

Where is smooth muscle most commonly found?

A
  • Walls of hollow organs
  • Bloood vessels
  • Respiratory/urinary system
  • Eyes
  • Skin
49
Q

What is the equivalent of Z-discs found in smooth muscle?

A

Dense bodies

50
Q

Define:

Calveoli

A

Membrane indentations that supply calcium ions via the sarcoplasmic reticulum

51
Q

What is cross-bridge formation regulated by in smooth muscle cells?

A

Calmodulin

52
Q

What is the stress-relaxation response in visceral smooth muscle?

A

Mechanical stress from stretching muscle triggers contraction followed by relaxation.

53
Q

What is the function of somites?

A

Give rise to myoblasts

54
Q

Define:

Myoblast

A

Muscle stem cell

55
Q

Define:

Fibrosis

A

Scar tissue

56
Q

What is the function of satellite cells?

A

Help repair skeletal muscle cells

57
Q

How is smooth muscle regenerated?

A

From pericytes

Anatomy & Physiology (12 decks)

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