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Physiology > Chapter 9 part 1 > Flashcards

Chapter 9 part 1 Flashcards

1
Q

What is nearly half of the body’s mass and why?

A

Muscle tissue because it holds a lot of water

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2
Q

What does muscle tissue do for the body?

A

Converts chemical energy in the form of ATP into directed mechanical energy that exerts a force

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3
Q

What are the three types of muscle tissue?

A

Skeletal
Cardiac
Smooth

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4
Q

What are three prefixes for muscle?

A

Myo
Mys
Sarco

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5
Q

What are skeletal muscle cells called?

A

Muscle fibers (elongated)

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6
Q

Are skeletal muscles striated or smooth? Voluntary or involuntary? Multinucleated or uninucleated?

A

Striated
Voluntary (require nervous system stimulation)
Multinucleated

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7
Q

Where does nervous system stimulation happen in skeletal muscles?

A

At the neuromuscular junction

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8
Q

Describe cardiac muscle?

A

In heart
Involuntary (no nervous system stimulation needed)
Striated
Intercalated discs/branched

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9
Q

Where do you find smooth muscle?

A

walls of hollow organs
Bladder
Stomach
airways

Spindle shaped and uninucleated

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10
Q

What are the 4 special characteristics of muscle tissue?

A

Excitability
Contractility
Extensibility
Elasticity

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11
Q

What is excitability?

A

The ability to receive and respond to stimuli

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12
Q

What is contractility?

A

The ability to shorten forcibly when stimulated

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13
Q

What is extensibility?

A

Ability to be stretched

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14
Q

What is elasticity?

A

Ability to recoil to resting length

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15
Q

What are the 4 important functions of muscles?

A

Movement
Maintaining posture and body position
Stabilizing joints
Heat generation

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16
Q

What do nerve endings do for skeletal muscles?

A

They regulate contraction (requires stimulation from nervous system)

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17
Q

What do arteries and veins do for the skeletal muscles?

A

Deliver nutrients and oxygen, remove waste

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18
Q

What is the epimysium?

A

Dense irregular connective tissue that surrounds entire muscles

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19
Q

What is the perimysium?

A

Fibrous connective tissue surrounding fascicles (group of muscle fibers)

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20
Q

What is the endomysium?

A

Areolar connective tissue surrounding each muscle fiber

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21
Q

Where do skeletal muscles attach?

A

To the insertion (movable bone) and the origin (immovable bone)

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22
Q

What is direct attachment of skeletal muscles?

A

Where the epimysium is fused to periosteum of bone or perichondrium of cartilage

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23
Q

What is indirect attachment of skeletal muscle?

A

The connective tissue wrappings extend beyond muscle as ropelike tendon or sheet like aponeurosis (on front of skull)

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24
Q

What is the sarcolemma?

A

The plasma membrane of skeletal muscle

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25
Q

What is the sarcoplasm?

A

The cytoplasm of skeletal muscle fibers

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26
Q

What do glycosomes do?

A

They store glycogen in the skeletal muscle fibers

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27
Q

What does myoglobin do?

A

They store oxygen in the skeletal muscle fibers

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28
Q

What do myofibrils contain?

A

Sarcomeres (contractile unit)

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29
Q

What are myofibrils?

A

Densely packed rodlike elements

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30
Q

What are striations of skeletal muscle fiber?

A

Repeating series of dark A bands and light I bands

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31
Q

What is the H zone of striations?

A

Lighter region in midsections of dark A band where filaments do not overlap

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32
Q

What is the M line?

A

Line of protein myomesin that bisects the H zone

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33
Q

What is the Z disc?

A

Sheet of protein on midline of light I band

Anchors thin filaments and connects myofibrils to one another

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34
Q

What runs the entire length of an A band?

A

Thick filaments

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35
Q

What runs the entire length of the I band and partway into A band?

A

Thin filaments

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36
Q

What runs from the z disc to z disc?

A

Sarcomere

37
Q

What are thin filaments made up of?

A

Actin myofilaments

38
Q

What are thin filaments anchored to?

A

Zdiscs

39
Q

What are thick filaments made up of?

A

Myosin myofilaments

40
Q

Where are thick filaments connected?

A

At the M line

41
Q

What do myosin tails contain?

A

2 interwoven, heavy polypeptide chains

42
Q

What is contained in the myosin heads?

A

2 smaller, light polypeptide chains that act as CROSS BRIDGES during contraction

43
Q

What do myosin heads act as?

A

Binding sites for actin of thin filaments
Binding sites for ATP
ATPase enzymes

44
Q

Where are the active sites for myosin head attachments during contraction?

A

Actin

45
Q

What regulates actin binding to myosin heads?

A

Tropomyosin and troponin

46
Q

What are elastic filaments of myofibrils made up of?

A

The protein titin

47
Q

What do the elastic filaments of myofibrils do?

A

Hold the thick filaments in place
Helps recoil after stretch
Resist excessive stretching

48
Q

What does dystrophin do?

A

Links the filaments to proteins of the sarcolemma (plasma membrane of the muscle cell)

49
Q

What 3 proteins bind filaments together and maintain alignment?

A

Nebulin
Myomesin
C proteins

50
Q

What kind of ER is the sarcoplasmic reticulum?

A

Smooth ER

51
Q

What is the function of the sarcoplasmic reticulum?

A

Regulation of intracellular Ca2+ levels (stores and releases calcium)

52
Q

What forms perpendicular cross channels in the SR?

A

Pairs of terminal cisterns

53
Q

Label the SR, Terminal Cisterna, and sarcolemma

A
54
Q

What are T Tubules?

A

Continuations of sarcolemma in which its lumen (inside) is continuous with the Extracellular space

55
Q

What do T tubules do for the muscle fiber’s surface area?

A

Increase the surface area

56
Q

Where do T tubules penetrate the cell’s interior?

A

At each A band - I band junction

57
Q

What are the triads of muscle fibers?

A

Paired terminal cisterns and T tubule

58
Q

What do the T Tubules do for muscle action potential?

A

They bring action potentials into the interior of muscle fiber (they must be stimulated by nervous system)

59
Q

What happens to the lengths of individual thick and thin filaments in the sliding filament model of contraction?

A

They do not change in length (does not necessarily cause shortening of fiber)

60
Q

When does shortening occur of the muscle fiber?

A

When tension generated by cross bridges on think filaments exceeds forces opposing shortening (not isometric)

61
Q

In what state do thin and thick filaments only overlap at ends of A band?

A

Relaxed state

62
Q

What happens during the sliding filament model of contraction?

A

Thin filaments slide past thick filaments (actin and myosin overlap more)

63
Q

When does contraction occur?

A

When myosin heads bind to actin (cross bridges are formed)

64
Q

How does sliding begin in the sliding filament model of contraction?

A

Myosin heads bind to actin and sliding begins

65
Q

How does ratcheting thin filaments toward center of sarcomere work?

A

Cross bridges form and break several times (this causes shortening of the muscle fiber)

Z discs are pulled toward the M line

66
Q

What happens when the intracellular Ca2+ concentration is low?

A

Tropomyosin (blocker) blocks active sites on actin so that myosin heads cannot attach to actin
(muscle fibers relax)

67
Q

What happens at higher intracellular Ca2+ concentrations?

A

Troponin changes shape when Calcium binds to it and moves tropomyosin out of the way so that myosin heads bind to actin
(causes sarcomere shortening and muscle contraction)

68
Q

How does muscle contraction end?

A

When nervous stimulation ceases, Calcium ions are pumped back into the sarcoplasmic reticulum and contraction ends

69
Q

How are cross-bridges formed?

A

High-energy myosin heads attach to thin filaments (actin)

70
Q

What happens during a working (power) stroke?

A

Myosin head pivots and pulls thin filament toward M line

71
Q

What happens during cross bridge detachment?

A

ATP attaches to myosin head and cross bridges detaches

72
Q

What is meant by “cocking” of myosin head?

A

Energy from hydrolysis of ATP cocks myosin head into high energy state (resets itself)

73
Q

What happens during rigor mortis?

A

Cross bridges do not detach because it requires ATP so the body stays contracted
(dying cells take in calcium and cross bridges are formed)

74
Q

What is needed for activation of skeletal muscles?

A

Nervous system stimulation

Action potential must be generated in sarcolemma

75
Q

What is EC coupling?

A

Excitation-contraction coupling is when action potentials propagate along the sarcolemma and intracellular calcium levels must rise briefly

76
Q

What are the two layers of smooth muscle?

A

Longitudinal (fibers parallel to long axis of organ- contraction leads to shortening)
Circular (fibers in circumference of organ- contraction leads to elongation)

77
Q

What is peristalsis?

A

Alternating contractions and relaxations of smooth muscle layers that mix and squeeze substances through lumen of hollow organs

78
Q

What type of cells are seen in smooth muscle fibers?

A

Thin and short, only one nucleus, no striations

79
Q

What connective sheaths are seen in smooth muscle?

A

It lacks connective tissue sheaths it only contains endomysium only

80
Q

How is the sarcoplasmic reticulum in smooth muscle related to the SR in skeletal muscle?

A

It is less developed in smooth muscle because it does not depend on nervous system stimulation

81
Q

What binds to calcium ions in smooth muscle?

A

Calmodulin

There are no sarcomeres, myofibrils, or T tubules

82
Q

What are dense bodies in smooth muscle?

A

Proteins that anchor non-contractile intermediate filaments to sarcolemma at regular intervals

83
Q

What type of junctions are in smooth muscle?

A

Gap junctions

We want smooth muscle to contract in synchronicity (peristalsis)

84
Q

What type of movement do smooth muscle fibers contract?

A

Corkscrew manner

85
Q

What energizes the sliding process in the contraction of smooth muscle?

A

ATP

actin and myosin interact by sliding filament mechanism

86
Q

Where is calcium obtained in smooth muscle for smooth muscle contraction?

A

From the SR and extracellular space (mainly extracellular space because SR is underdeveloped)

87
Q

How are smooth muscle contracted?

A

Calcium binds to and activates calmodulin
Activated calmodulin activates myosin kinase
Myosin kinase Phosphorylates and activates myosin
Cross bridges interact with actin and contraction occurs

88
Q

What does smooth muscle relaxation require?

A

Active transport of calcium into SR and ECF to decreasing intracellular calcium (dephosphorylation of myosin to reduce myosin ATPase activity)`

Physiology (17 decks)

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