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DAT Biology > Chapter 11.5 - Muscular System > Flashcards

Chapter 11.5 - Muscular System Flashcards

1
Q

Where is smooth muscle found

A

walls of our organs, airways, blood vessels

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2
Q

Smooth muscle is not:

A

striated

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3
Q

smooth muscle contracts and relaxes:

A

involuntarily

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4
Q

What gives muscles a striated appearance?

A

sarcomeres

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5
Q

cardiac muscle contracts and relaxes:

A

involuntarily

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6
Q

cardiac muscle has __ nucleus/nuclei per cell

A

1 nucleus

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7
Q

Which muscles are striated?

A

skeletal and cardiac

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8
Q

Which muscle contains intercalated discs?

A

cardiac cells

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9
Q

Intercalated discs contain:

A

desmosome and gap junction

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10
Q

Gap junction allows for:

A

cells can pass ions quickly allowing heart to depolarize and contract in unison

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11
Q

skeletal muscle cells are:

A

long, multinucleated, striated

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12
Q

Smallest to largest unit of skeletal muscle

A

myofibril –> muscle fiber –> fascicles –> muscle

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13
Q

protective sheath encasing the muscle fiber:

A

sarcolemma

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14
Q

Cytoplasm of muscle fiber

A

sarcoplasm

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15
Q

Epimysium

A

The most superficial sheath. Covers the muscle itself

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16
Q

Perimysium

A

Covers the muscle fascicles

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17
Q

Endomysium

A

the deepest sheath, covers muscle fibers

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18
Q

Myofibril contain many repeating units called:

A

sarcomeres

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19
Q

Functional unit of muscle fibers

A

sarcomeres - shorten to faciliatte muscle contraction

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20
Q

Neuromuscular junction

A

space between the presynaptic motor neuron and postsynaptic muscle fiber

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21
Q

When a motor neuron sends an action potential, it releases ___ into the ___ ___

A

acetylcholine; neuromuscular junction

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22
Q

Steps to transfer action potential to muscle

A
  1. acetylcholine released at neuromuscular junction, binds to voltage gated Na+ channels
  2. graded potential created (small depolarization)
  3. opens more Na+ channels
  4. creates action potential in muscle
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23
Q

T-tubules

A

invaginations in the sarcolemma - allow the action potential initiated on the muscle fiber to spread throughout the cell very quickly, ensuring a coordinated contraction

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24
Q

Muscles contract across:

A

a joint

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25
Q

Muscles __ the bone they ___ upon closer to the bone they ____ from

A

pull; insert; originate

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26
Q

Muscle contraction is always:

A

a pull motion

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27
Q

The sarcolemma is:

A

muscle fiber’s cell membrane

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28
Q

sarcomeres contain:

A

array of long filament proteins (myofilaments)

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29
Q

Examples of myofilaments

A

thin actin filaments, thick myosin filaments

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30
Q

neuromuscular junction

A

space between the presynaptic motor neuron and postsynaptic muscle fiber

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31
Q

Which NT is released by a motor neuron?

A

Acetylcholine

32
Q

What does acetyl choline do once it is released by motor neuron?

A

creates graded potential - facilitates the opening of ligand gated sodium channels on the muscle fiber

33
Q

Invaginations in the sarcolemma

A

T-tubules

34
Q

Sarcoplasmic reticulum

A

specialized ER that stores calcium ions in muscle fibers

35
Q

What causes voltage gated Ca2+ channels to open?

A

Depolarization traveling across T-tubules

36
Q

When Ca2+ is released, it travels from ___ to ___

A

sarcoplasmic reticulum; sarcoplasm

37
Q

actin’s binding site for myosin is covered by:

A

tropomyosin

38
Q

Tropomyosin is held in place by

A

troponin

39
Q

How does tropomyosin move away from myosin binding site?

A

Ca2+ in sarcoplasm binds to troponin

40
Q

Troponin has _ binding sites:

A

3; A, C, T

41
Q

troponin A site

A

binds actin

42
Q

troponin C site

A

binds Ca2+

43
Q

troponin T site

A

binds tropomyosin

44
Q

How does myosin form cross bridge?

A

hydrolyzes ATP to extract energy, enters high energy state to bind to actin forming cross bridge

45
Q

What happens when myosin releases ADP and Pi?

A

power stroke

46
Q

rigor mortis

A

happens in dead animals, no ATP being produced –> myosin released from actin –> maintains contraction

47
Q

Z line

A

periphery (ends) of each sarcomere

48
Q

M line

A

midpoint of each sarcomere

49
Q

I bands

A

areas where only actin is present (including where Z line is)

50
Q

A bands

A

areas where myosin and actin overlap

51
Q

H zone

A

where only myosin is present

52
Q

Which band does not shorten during muscle contraction?

A

A band

53
Q

Small motor units

A

few muscle fibers, innervated by single motor neuron

54
Q

Precision movements are created by:

A

small muscles containing many motor units

55
Q

large motor units have:

A

many muscle fibers, innervated by one motor neuron

56
Q

How are powerful movements created? (how many motor units)

A

large muscles with few motor units

57
Q

What is a twitch contraction?

A

brief contraction a muscle fiber experiences as the result of a single action potential stimulating an entire motor unit

58
Q

All-or-none principle of muscle contraction

A

Either the depolarization is above threshold in which all fibers twitch, or it is below threshold and none twitch

59
Q

Phases of twitch

A

latent; contraction; relaxation

60
Q

Muscle fiber types

A
  1. slow oxidative fibers
  2. fast oxidative-glycolytic fibers
  3. fast glycolytic fibers
61
Q

___ fibers have the slowest acting myosin ATPase

A

Type I

62
Q

Type I fibers = ___

A

slow oxidative fibers

63
Q

Type II-a fibers:

A

Fast oxidative-glycolytic fibers

64
Q

type II-b fibers

A

Fast glycolytic fibers

65
Q

Describe slow oxidative fibers

A
  • small diameter (weak contractions)
  • dark red
  • aerobic respiration
  • efficient
  • resistant to fatigue
66
Q

Describe fast oxidative glycolytic fibers

A
  • intermediate diameter
  • dark red
  • an/aerobic respiration
  • reasonably efficient but susceptible to fatigue
67
Q

Describe fast glycolytic fibers

A
  • white
  • anaerobic respiration
  • strongest contractions
  • somewhat inefficient, fatigues quickly
68
Q

True or false: since twitch will always be the same size, overall force of contraction remains the same

A

false - contraction varies due to wave summation/ motor unit summation

69
Q

wave summation

A

refers to the process of depolarizing muscle fibers in a motor unit again during their relaxation period

70
Q

Tetanus

A

process where the muscle fibers of a motor unit are being maximally stimulated by a motor neuron and tension can no longer increase

71
Q

Tetanus usually happens when:

A

sending action potentials down a motor neuron with such a high frequency that we don’t experience any relaxation

72
Q

Motor unit summation affects force of contraction because:

A

action potentials are traveling to different motor units at different times

73
Q

Muscle tone (tonus)

A

due to weak and involuntary twitches of small groups of motor units within a muscle, due to a continuous output of action potentials from the brain and spinal cord

74
Q

True or false: continuous muscle tonus causes fatigue

A

False - we never feel fatigued by our tonus because different motor units of a muscle are being stimulated at different times

75
Q

Which muscle has no inherent muscle tone?

A

cardiac muscle tone

76
Q

Hypotonicity

A

muscles lose tone and thus feel flaccid. occurs as the result of damage to PNS/reduced electrolytes

77
Q

hypertonicity

A

when muscles gain tone and thus feel spastic and rigid; occurs as the result of damage to the central nervous system.

DAT Biology (27 decks)

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