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Anatomy and Physiology > Chapter 8: Muscle Tissue > Flashcards

Chapter 8: Muscle Tissue Flashcards

1
Q

What are the 4 major functional characteristics of muscles?

A
  1. Excitability
  2. Contractility
  3. Extensibility
  4. Elasticity
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2
Q

What is Excitability?

A

Muscle tissue has the capacity to respond to the stimulation of nervous impulses or hormones.

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3
Q

What is Contractility?

A

Muscle tissue has the capacity to shorten or contract with force.

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4
Q

What is Extensibility?

A

Muscle tissue can stretch beyond (within reason) resting length.

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5
Q

What is Elasticity?

A

Muscle tissue returns to resting length after being stretched.

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6
Q

What are the 3 types of muscle tissue?

A
  1. Skeletal muscle
  2. Smooth muscle
  3. Cardiac muscle
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7
Q

What are the major structural and functional differences among the 3 types of muscle tissue?

A
  1. Skeletal
    - primarily attached to bones
    - striated
    - voluntary
  2. Cardiac Muscle
    - forms wall of heart
    - striated
    - involuntary
  3. Smooth (visceral) Muscle
    - located in viscera
    - nonstriated (smooth)
    - involuntary
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8
Q

What are the 5 key function of muscle?

A
  1. produces body movements
  2. stabilizes body positions
  3. regulates organ volume
  4. moves substances within the body
  5. generates heat
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9
Q

What separated muscle from skin?

A

Superficial fascia

or subcutaneous layer

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10
Q

What are the function of superficial fascia?

A
  • separates muscle from skin
  • provide a pathway for nerves and blood vessels
  • stores fat
  • insulates
  • protects muscles from trauma
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11
Q

What is the function of deep fascia?

A
  • holds muscles with similar functions together
  • allows for free movement of muscles
  • carries nerves, blood vessels, and lymph vessels
  • fills spaces between muscles
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12
Q

What attached muscle to bone or muscle to other muscles?

A

Tendons and aponeuroses

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13
Q

What conveys impulses for muscular contractions?

A

Nerves (containing motor neurons)

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14
Q

What provides nutrients and oxygen for contraction?

A

Blood

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15
Q

Epimysium

A

covers the entire muscle

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16
Q

Perimysium

A

Covers the fasciculi

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17
Q

Endomysium

A

Covers individual muscle fibres.

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18
Q

What is a muscle fiber?

A

thousands of elongated, cylindrical cells arranged parallel to one another.

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19
Q

Each muscle fiber is covered by a plasma membrane called ________.

A

Sarcolemma

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20
Q

What is muscle fibers cytoplasm called?

A

Sarcoplasm

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21
Q

What does sarcoplasm contain?

A

Many mitochondria that produce large amounts of ATP during muscle contractions.

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22
Q

What is sacroplasmic reticulum and what dose it store?

A
  • encircles each myofibril
  • a network of fluid-filled membrane-enclosed tubules

stores calcium ions.

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23
Q

What are myofibrils composed of?

A

thick and thin filaments arranged in units called sarcomeres.

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24
Q

What are sarcomeres?

A

the basic functional units of a myofibril and show distinct dark (A band) and light (I band) areas.

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25
Q

Where does the Z discs pass through?

A

center of an I band

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26
Q

Where will you find an H zone?

A

center of a A band

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27
Q

What is a myofibril?

A

Cylindrical structures that extend along the entire length of muscle fiber.

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28
Q

When do contractile proteins generate force?

A

During contraction

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29
Q

What is myosin and what does it function as?

A
  • the main component of thick filaments

- functions as a motor protein.

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30
Q

What do motor proteins do?

A

push and pull their cargo to achieve movement by converting energy from ATP into mechanical energy of motion or force.

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31
Q

What is actin?

A

the main component of thin filaments,

- has myosin binding sites where myosin ‘heads’ attach to produce the sliding together of the filaments.

32
Q

The regulatory proteins tropomyosin and troponin are a part of _______.

A

the thin filament

33
Q

What does troponin do?

A

holds tropomyosin in place.

34
Q

What happens in a relaxed muscle?

A

tropomyosin blocks the myosin-binding sites on actin to prevent myosin from binding to actin.

35
Q

What happens during a contraction?

A

myosin heads pull on the actin and shorten the muscle cell (during contraction)

36
Q

What is the process called when myosin heads pull on the actin and shorten the muscle cell?

A

the sliding-filament mechanism

37
Q

Before a skeletal muscle fiber can contract, it must be stimulated by an electric signal called?

A

a muscle action potential

38
Q

Where do muscle action potentials arise from?

A

neuromuscular function (NMJ)

39
Q

What is the neuromuscular junction (NMJ)?

A

the synapse between a somatic motor neuron and a skeletal muscle fiber

40
Q

What is a motor unit?

A

a nerve and the muscle fibers in stimulates.

41
Q

What is a synapse?

A

a region of communication between 2 neurons or a neuron and target cell.

42
Q

What do neurotransmitters do?

A

bridge the gap between 2 neurons or
a neuron and a target cell, or
a synaptic cleft.

43
Q

What is the neurotransmitter at a NMJ?

A

acetylcholine (ACh)

44
Q

What happens during muscle contraction?

A
  • myosin-cross-bridges pull on thin filaments, causing them to slide inward toward the H zone
  • Z discs come toward each other and sacromeres shorten
45
Q

What is the sliding-filament mechanism?

A

the sliding of filaments and shortening of sacromeres causes the shortening of whole muscle fiber and entire muscle.

46
Q

How are calcium ions returned to the sacroplasmic reticulum?

A

Active transport pumps

47
Q

What starts a muscle contraction?

A

an increase of calcium ion concentration in the cytosol.

48
Q

What stops a muscle contraction?

A

the decrease of calcium ion concentration in the cytosol.

49
Q

What are the 4 steps of the contraction cycle?

A
  1. Splitting ATP
  2. Forming cross-bridges
  3. Power stroke
  4. Binding ATP and detaching
50
Q

What is the contraction cycle?

A

a repeating sequence of events that cause the filaments to slide.

51
Q

At any given moment, a few muscle fibers within a muscle are contracted, while most are relaxed. Why is this important?

A

this small amount of contraction is essential for maintaining posture.

52
Q

What is muscle tone?

A

a sustained partial contraction of portions of a relaxed skeletal muscle.

53
Q

When goes muscle fatigue occur?

A

When a muscle cannot produce enough ATP to meet its needs.

54
Q

What is muscle fatigue?

A

the inability of a muscle to maintain its strength of contraction or tension.

55
Q

What are the 2 sources of oxygen for muscle tissue?

A
  1. Diffusion from blood

2. Release by myoglobin inside muscle fibers.

56
Q

What can aerobic cellular respiration (reactions requiring oxygen) provide?

A
  • completes the oxidation of glucore via cellular respiration
  • and provides energy from prolonged activity.
57
Q

What can anaerobic cellular respiration (glycolysis) provide?

A

enough energy for about 30-40 seconds.

58
Q

What can creative phosphate provide?

A

can power maximal muscle contraction for about 15 seconds

—-used for maximal short bursts of energy.

59
Q

What are the 3 sources for ATP production in muscle cells?

A
  1. Creatine Phosphate
  2. Anarobic cellular respiration (glycolysis)
  3. Aerobic cellular respiration (reactions requiring oxygen)
60
Q

What are the 3 periods of a twitch contraction?

A
  1. Latent
  2. Contraction
  3. Relaxation
61
Q

What is a twitch?

A

a brief contraction of all the muscle fibers in a motor unit in response to a single action potential.

62
Q

What is a complete (fused) tetanus?

A

sustained contraction that lacks even partial relaxation between stimuli.

63
Q

What is a incomplete (unfused) tetanus?

A

A sustained muscle contraction that permits partial relaxation between stimuli.

64
Q

What is wave summation?

A

The increased strength of a contraction.

—- result of the application of a second stimulus before muscle has completely relaxed after a previous stimulus.

65
Q

What are the 3 main types of skeletal muscles based on structure and function?

A
  1. slow oxidative
  2. fast oxidative-glycolytic
  3. fast glycolytic fibers.
66
Q

What is isometric contraction?

give example

A

a contraction that occurs when tension is applied to muscle but it doesn’t shorten.
ex. carrying a box of book.

67
Q

What is isotonic contraction?

give example

A

a contraction that occurs when tension in muscle remains the same but muscle shortens.
ex. when you lift a textbook from a table.

68
Q

When do cardiac muscles contract?

A

When stimulated by their own autohythmic fibers.

69
Q

Where can you find cardiac muscle?

A

Only in the heart walls.

70
Q

How do cardiac muscle fibers connect to adjacent fibers?

A

by intercalacted discs that contain desmosomes and gap junctions.

71
Q

What is the stress-relaxation response?

A

Smooth muscle fibers can stretch considerably without developing tension.

72
Q

What happens when calmodulin activates the enzyme myosin light chain kinase?

A

it facilitates myosin-actin binding and allows contraction to occur at a relatively slow rate.

73
Q

In smooth muscle, what is the regulator protein that binds calcium ions in the cytosol?

A

Calmodulin (in striated muscle, the regulator protein is troponin)

74
Q

What takes longer in smooth muscle that is skeletal muscle?

A

Duration of contraction and relaxation.

75
Q

Where is multi-unit smooth muscle found?

A

In large blood vessels, large airways, arrector pili muscle and the iris of the eye.

76
Q

Where is visceral smooth muscle found?

A

In the walls of hollow viscera and small blood vessels.

77
Q

What are the 2 types of smooth muscle?

A
  1. Visceral (single unit) smooth muscle

2. Multi-unit smooth muscle

Anatomy and Physiology (18 decks)

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