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PHYSIOLOGY > CONTRACTION OF SKELETAL MUSCLE > Flashcards

CONTRACTION OF SKELETAL MUSCLE Flashcards

1
Q

…gives muscle its muscle its striated appearance

A

The light band(I) and the dark band (A)

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2
Q

The length at which actin finally overlaps the myosin is…

A

Sarcomeres

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3
Q

Skeletal muscle is composed of fibers that are …um in diameter

A

10-80um

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4
Q

The small unit of muscle fibers are

A

sarcomalemma, myofibril,sarcoplasmic reticulum

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5
Q

The true membrane of sarcomalemma is called..

A

Plasma membrane

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6
Q

…is the cell membrane of muscle fibers

A

Sarcomalemma

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7
Q

The outer coat of sarcomalemma contains thin polysaccharide that contains…

A

Thin collagen fibrils

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8
Q

The surface of…fuses with tendon fiber at the end of each muscle fiber

A

Sarcolemma

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9
Q

Myofibril consist of

A

Actin and myosin

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10
Q

….are the large protein polymer that is responsible for the actual muscle contraction

A

Actin and myosin filaments

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11
Q

… interdigitate and cause the myofibril to form light and dark band

A

Actin and myosin filaments

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12
Q

The light bands and dark band are … respectively

A

Actin and myosin

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13
Q

Light band are called …. because of..

A

(I) band because they are isotropic to polarized light

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14
Q

Dark band are called… because they..

A

(A) because they Anisotropic polarized light

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15
Q

What produces muscle contraction

A

The interaction btw actin and cross -bridge

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16
Q

The small projection from the side of myosin is …

A

Cross-bridges

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17
Q

…is a disc composed of filamentous protein that help attach myofibril from one another across the muscle fibers

A

Z-disc

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18
Q

Actin filaments is attached to…disc which the actin interdigitate with myosin

A

Z-disc

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19
Q

Skeletal muscle is about ..%of the body while smooth and cardiac muscle are about…%

A

40 and 1O respectively

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20
Q

The portion of myofibril that lies between two successive Z disc is called

A

Sarcomeres

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21
Q

As the muscle contracts the sarcomeres reduces by…

A

2um

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22
Q

…is the filamentous protein with the largest MMW of 3million

A

Titin protein

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23
Q

The largest filamentous protein is

A

Titin protein

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24
Q

Titin protein is …in nature

A

Springy

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25
Q

What’s the function of titin protein

A

It acts as a framework that holds the myosin and actin together in place so that the contractile machinery if sarcomeres will work

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26
Q

The space between myofibrils that are filled with intracellular fluid is …

A

Sarcoplasm

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27
Q

Sacroplasm contain large qty of

A

Potassium, magnesium phosphate, multiple protein enzyme and mitochondria

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28
Q

… supplies the contracting myofibril energy in form of ATP

A

Mitochondria

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29
Q

The sarcoplasm that surrounds the myofibril contains …that control the muscle contraction

A

Sarcoplasmic reticulum

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30
Q

How many mechanisms are involved in muscle contraction

A

8 steps

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31
Q

The neurotransmitter secreted by nerve at each endings on muscle fibers is

A

Acetylcholine

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32
Q

What is the function of acetylcholine

A

It acts on a local area of the muscle fibers membrane to open multiple acetylcholine gated channels through protein molecules floating in the membrane

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33
Q

Na ions that diffuses inside the muscle fibers membrane initiate ..

A

Action potential at the membrane

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34
Q

Opening of acetylcholine gate allows…

A

The diffusion of Na ions

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35
Q

Where is calcium stored …

A

Sarcoplasmic reticulum

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36
Q

… depolarizes muscle membrane and causes electric flow through the counter of the muscle

A

Action potential

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37
Q

The removal of calcium causes myofibril to

A

Cease

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38
Q

Muscle contraction occurs by… mechanism

A

Sliding filament mechanism

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39
Q

The interaction of myosin cross-bridges with actin filaments causes the actin filaments to slide.. . among myosin filaments

A

Inward

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40
Q

… activates the forces btw actin and myosin filaments which causes contraction to begin

A

Calcium ion

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41
Q

The end of myosin functions as… enzyme

A

ATPase

42
Q

ATPase enzyme…ATP which energizes the contraction process

A

Hydrolysis

43
Q

The actin filament is made up of

A

Actin, tropomyosin and troponin

44
Q

The actin filaments is inhibited by…and activated by…

A

Troponin -tropomyosin complex
Calcium ions

45
Q

Ca2+ combines with… causing troponin complex to pull on the tropomyosin molecules

A

Troponin

46
Q

Another name for walk along theory is

A

Ratchet theory

47
Q

The tilting of the myosin head

A

Power stroke

48
Q

Tension…as sarcomeres shortens

A

Increases

49
Q

Full tension is achieved at … sarcomeres length

A

2um

50
Q

Functions of ATP in muscle contraction

A

Activate walk along mechanism
Pump ca2+ ion in sarcoplasmic reticulum
Pumping of Na and K ions to maintain ionic movement for the propagation of ATP

51
Q

3 main sources of energy apart from ATP

A

Phosphocreatine
Glycogen breakdown to pyruvic and lactic acid
Oxidative metabolism of cellular foodstuff

52
Q

How long does phosphocreatine, glycogen breakdown and oxidative metabolism of cellular foodstuff maintain contraction respectively

A

5-8sec,1min and for a long period

53
Q

2 characteristics of whole muscle contraction are

A

Isotonic contraction and
Isometric contraction

54
Q

… contraction occurs when muscle does not shorten during contraction

A

Isometric contraction

55
Q

… contraction occurs when the muscle shortens and tension on the muscle remains constant

A

Isotonic

56
Q

True isometric contraction cannot be generated in intact body because of the stretch of the stretch of series of elastic components during muscle contraction allowing shortening of the muscle. T) F

A

T

57
Q

The elastic element include

A

Tendon
Sarcolemma end of muscle fibers
Hinged arm of myosin cross-bridges

58
Q

Characteristics of isotonic contraction depends on..

A

Load against muscle contraction
Inertia of the load

59
Q

Types of muscle fibers are

A

Fast fibers
Slow fibers

60
Q

Each muscle is composed of…type of fiber

A

Both

61
Q

Another name for slow fibers and fast fibre respectively

A

Type 1/red muscle
Type 2/white fibers

62
Q

…fiber is characterized by large amount of myoglobin,smaller nerve fiber, high capillarity and large number of mitochondria

A

Slow fibers

63
Q

What gives muscle its reddish appearance

A

Myoglobin

64
Q

…fiber has extensive sarcoplasmic reticulum for rapid release of ca2+,larger with large amount of glycolytic enzyme, lower capillarity with few mitochondria

A

Fast fibers

65
Q

Fast fibers have fewer mitochondria because… metabolism is of secondary importance

A

Oxidative

66
Q

… fibers contains glycolytic enzyme

A

Fast

67
Q

…is each motor neuron that leaves the spinal cord and innervates multiple muscle fibers

A

Motor unit

68
Q

…is the addition of individual twitch contraction to increase the intensity of overall muscle contraction

A

Force summation

69
Q

…is a single sudden contraction that lasts for a fraction of seconds

A

Twitch

70
Q

Two ways summation occurs are

A

Multiple motor unit summation
Frequency summation and tentanization

71
Q

What is multiple motor

A

It is when the CNS sends a weak signal to contract muscle ,the motor unit in the muscles contains the smallest and fewest muscle fibers stimulated in preference to the larger motor units

72
Q

Increase in the total mass of muscle

A

Muscle hypertrophy

73
Q

The enzyme that increases in muscle hypertrophy is known as

A

Glycolytic enzyme

74
Q

The decrease in the mass of a muscle is

A

Muscle atrophy

75
Q

Increase in fiber number is …

A

Hyperplasia of muscle fibers

76
Q

…occurs as a result of linear splitting enlarged fibers

A

Hyperplasia

77
Q

Destroyed nerve fiber are replaced by…

A

Fibrous and fatty tissue

78
Q

The continuous shortening of fibrous tissue for many months is known as

A

Contracture

79
Q

What is denervation

A

It is the lose of nerve supply

80
Q

Recovery of muscle contraction in poliomyelitis is caused by …

A

Macro motor unit

81
Q

Several hours after death,all muscles go into a state of contracture called

A

Rigor mortis

82
Q

A state of muscle rigidity without action potential is known as

A

Rigor mortis

83
Q

Rigor mortis is as a result of

A

Loss of ATP

84
Q

A body remains rigor until …takes place

A

Autolysis

85
Q

Drugs that inactivate acetylcholinestrase are

A

Psyostigmine
Neostigmine and
Diflos

86
Q

Drug that blocks the neuromuscular transmission

A

Curaciform

87
Q

Drugs that have the same action as acetylcholine are

A

Methocholine
Carbachol
Nicotine

88
Q

…is used by military as a powerful nerve gas poison

A

Diflos

89
Q

Myasthenia gravis cause

A

Paralysis

90
Q

The pathogen myasthenia gravis is a … disease

A

Autoimmune disease

91
Q

The patient suffering from paralysis dies mostly of

A

Respiratory paralysis

92
Q

Two types of smooth muscle are

A

Multi-unit smooth muscle
Single unit smooth muscle

93
Q

The unique characteristics of multi-unit smooth muscle are

A

They contract independent of others
They are control by nerve signal

94
Q

Multi-unit smooth muscle are innervated by… nerve endings

A

Single

95
Q

Examples of smooth muscle fibers are

A

Ciliary of the eyes
Iris
Piloerector

96
Q

Another name for single unit smooth muscle are

A

Visceral
Syncytial or
Unitary smooth muscle

97
Q

They are called single unit smooth muscle because

A

Hundreds of millions of muscle fibers contract as a single unit

98
Q

The cell membrane of single unit smooth muscle are joined together by … junction

A

Gap

99
Q

The type of muscle mostly found in hollow are

A

Single unit smooth muscle

100
Q

Single unit smooth muscle in blood vessel…and …, they propel contents of…and expel the content of…

A

Regulate blood vessel diameter and part of respiratory system
Gut walls,bile, ureter and uterus
Uretus and urinary bladder

101
Q

Physical basis for smooth muscle contraction are

A

Actin filaments attached to dense bodies
Myosin filaments interspersed among the actin filaments
Contractile unit

PHYSIOLOGY (2 decks)

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