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Muscle Physiology > Muscle > Flashcards

Flashcards in Muscle Deck (107)
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0
Q

Contractility

A

The ability of muscle to shorten forcefully

1
Q

Functions of the muscular system

A

Movement, maintenance of posture, respiration, body heat, communication, constriction of organs and vessels, contraction of the heart

2
Q

Excitability

A

The capacity of muscle to respond to a stimulus

3
Q

Extensibility

A

A muscle can be stretched beyond its normal resting length and still be able to contract

4
Q

Elasticity

A

Ability of muscle to recoil to its original resting length after it has been stretched.

5
Q

Types of muscle

A

Skeletal, smooth, cardiac

6
Q

Skeletal muscle

A

Associated with connective tissue. About 40% of body weight. Locomotion, facial expressions, posture, respiratory etc

7
Q

Smooth muscle

A

Most widely distributed throughout body. Walls of hollow organs and tubes, interior of eye, walls of blood vessels,

8
Q

Cardiac muscle

A

Only in heart. Many smooth muscles that contract rhythmically. Controlled by nervous system and endocrine system

9
Q

Skeletal muscle fibers

A

Skeletal muscle cells

10
Q

Fasciculi

A

Visible bundles of muscle

11
Q

Perimyseum

A

Connective tissue layer surrounding fasciculi

12
Q

Epimysium

A

Surrounds entire muscle. Dense collagenous connective tissue.

13
Q

Fascia

A

General term for connective tissue sheets within the body

14
Q

Muscular fascia

A

Superficial to epimysium, separates and compartmentalizes individual muscle groups

15
Q

Motor neurons

A

Specialized nerve cells that stimulate muscles to contract

16
Q

Myoblasts

A

Muscle fibers develop from less mature, multinucleated cells called myoblasts

17
Q

Hypertrophy

A

Enlargement

18
Q

Sarcolemma

A

Plasma membrane of a muscle fiber. Two layers

19
Q

External lamina

A

Deeper thinner layer of sarcolemma. Cannot be distinguished under light microscope

20
Q

Endomysium

A

Second layer of sarcolemma. Thicker layer

21
Q

Transverse (t) tubules

A

Tube like invanginations of sarcolemma. Connects extra cellular environment with interior of muscle fiber

22
Q

Sarcoplasmic reticulum

A

Endoplasmic reticulum in muscle cells

23
Q

Sarcoplasm

A

The cytoplasm of muscle cells. Contains energy-storing glycogen granules and mitochondria

24
Q

Myofibrils

A

Within sarcoplasm. Bundles of protein filaments I

25
Q

Myofilaments

A

Actin and myosin

26
Q

Sarcomeres

A

Actin and myosin myofilaments highly ordered units

27
Q

Actin Myofilaments are composed of

A

Two strands fibrous actin (f actin) tropomyosin molecules and troponin molecules

28
Q

Globular actin

A

G actin. Active site where myosin molecules bind during contraction

29
Q

Myosin molecules are

A

Myosin heavy chains to make a rid portion and myosin heads

30
Q

Cross-bridges

A

Myosin heads bind to active sites on actin to form cross bridges

31
Q

Myosin heads

A

ATPase enzymes which break down ATP and release energy.

32
Q

ATP

A

Adenosine triphosphate

33
Q

Z disk

A

Network of protein forming a dislike structure for the attachment of actin myofilaments

34
Q

I band

A

Isotropic band. Includes Z disk, and extends from one side to the other. Only actin filaments

35
Q

A band

A

Anisotropic band. Extends the length of myosin filaments within a sacromere

36
Q

H zone

A

Actin and myosin filaments do not overlap and only myosin is present

37
Q

M line

A

Middle of H zone. Chain in the middle that holds myosin in place

38
Q

Titin

A

Largest protein. Attaches to z disk to m line

39
Q

Ligand-gated ion channels

A

Ion channels that open as a result of a neurotransmitter

40
Q

Mv

A

Millivolts. Measures resting membrane potential

41
Q

Depolarization phase

A

Brief period during which further depolarization occurs and inside of cell becomes positively charged

42
Q

Repolarization phase

A

Return to resting value

43
Q

All or nothing principle

A

If depolarization reaches threshold, permeable changes proceed without stopping

44
Q

Propagate

A

Action potentials can travel across plasma membrane to adjacent location

45
Q

Neuromuscular junction

A

Synapse

46
Q

Presynaptic

A

Axon terminal

47
Q

Synaptic cleft

A

Space between presynaptic terminal and muscle fiber

48
Q

Postsynaptic membrane

A

Motor end plate. Muscle area of junction

49
Q

Synaptic vesicles

A

Spherical sacs on presynaptic terminal. Contain acetylcholine

50
Q

Acetylcholine

A

ACh. Neurotransmitter that alters post synaptic cell

51
Q

Acetylcholinesterase

A

Breaks down acetylcholine and keeps it from accumulating in the synaptic cleft.

52
Q

Excitation-contraction coupling

A

Action potential causes contraction

53
Q

Terminal cisternae

A

Near t tubules, the sarcoplasmic reticulum is enlarged to form terminal cisternae

54
Q

Triad

A

A t tubule and two adjacent terminal cisternae together

55
Q

Cross bridge cycling

A

During contraction, myosin molecules undergo cross bridge formation and return of position many times

56
Q

Power stroke

A

Movement of myosin molecule while cross bridge is attached

57
Q

Recovery stroke

A

Return of myosin head to its original position after cross bridge

58
Q

Muscle twitch

A

Single, brief contraction. Does not last long enough to perform any work

59
Q

Lag phase

A

Time between the application of stimulus to motor neuron and muscle contraction

60
Q

Contraction phase

A

Time when contraction occurs

61
Q

Relaxation phase

A

When relaxation occurs

62
Q

Motor unit

A

Single

Motor neuron and all the muscle fibers it innervates

63
Q

Graded

A

Strength of muscle contractions varies from weak to strong. Wholesales respond.

64
Q

Summation

A

Involves increasing the force of contraction of the muscle fibers

65
Q

Recruitment

A

Increasing number of muscle fibers contracting

66
Q

Treppe

A

A muscle fiber, when stimulated in rapid succession, contracts with greater force with each subsequent stimulus

67
Q

Multiple motor unit summation

A

Relationship between increasing stimulus strength and increased number of contracting motor units. More motor units with more force of contraction

68
Q

Subthreshold stimulus

A

Not strong enough to cause an action potential or contraction

69
Q

Threshold stimulus

A

Strong enough to produce an action potential in a single motor unit axon

70
Q

Submaximal stimuli

A

Produce action potentials in axons of additional motor units

71
Q

Maximal stimulus

A

Produces action potentials in the axons of all the motor units of that muscle

72
Q

Tetanus

A

Frequency of action potentials in skeletal muscle increases the frequency of contraction also increases until a period of sustained contraction

73
Q

Incomplete tetanus

A

Muscle fibers partially relax between the contractions

74
Q

Complete tetanus

A

No relaxation between contractions

75
Q

Multiple wave summation

A

When the frequency of contractions increases, the tension produced is called multiple wave summation

76
Q

Active tension

A

Force applied to an object to be lifted when a muscle contracts

77
Q

Active tension curve

A

Muscle length plotted against the tension produced by the muscle in response to maximal stimuli

78
Q

Passive tension

A

Tension applied to the load when a muscle stretches but is not stimulated

79
Q

Total tension

A

The sum of active and passive tension

80
Q

Isometric contractions

A

The length of the muscle does not change but the amount of tension increases during contraction

81
Q

Isotonic contractions

A

The amount of tension produced by the muscle is constant during contraction but the length of the muscle changes

82
Q

Concentric contractions

A

Isotonic contractions in which tensions in the muscle is great enough to overcome the opposing resistance and the muscle shortens

83
Q

Eccentric contractions

A

Isotonic contractions in which tension is maintained in a muscle to increase in length. Lowers heavy weight

84
Q

Muscle tone

A

Constant tension produced by muscles for long periods of time

85
Q

Fatigue

A

decreased capacity to do work and the reduced efficiency of performance that normally follows a period of activity

86
Q

Psychological fatigue

A

Involved central nervous system, individual perceives that no more work is possible

87
Q

Muscular fatigue

A

Calcium ion imbalances as ATP levels drop. Cross bridges cannot function properly.

88
Q

Synaptic fatigue

A

Neuromuscular junction. High frequency of acetylcholine without enough synthesizing.

89
Q

Physiological contracture

A

In cases of extreme fatigue. Muscles are not capable of contraction or relaxing. No ATP

90
Q

Rigor Mortis

A

Development of ridged muscles several hours after death, similar to physiological contracture

91
Q

Creative phosphate

A

Accumulates in muscle fibers where it stores energy that can be used to synthesize ATP

92
Q

Anaerobic respiration

A

Breakdown of glucose to yield ATP and lactic acid

93
Q

Glycolysis

A

Glucose molecule is broken down into two molecules of pyruvic acid. Lactic acid diffuses into bloodstream

94
Q

Aerobic respiration

A

Requires oxygen and breaks down glucose to produce ATP carbon dioxide and water.

95
Q

Oxygen deficit

A

Insufficient oxygen consumption relative to increased activity.

96
Q

Recovery oxygen consumption

A

Elevated oxygen levels after exercise has ended

97
Q

Slow twitch oxidative muscle fibers

A

Contract more slowly, better blood supply, more mitochondria and more fatigue resistant

98
Q

Myosin ATPase

A

Enzymes on the myosin heads responsible for the breakdown of ATP

99
Q

Myoglobin

A

Dark pigment similar to hemoglobin in RBC. Binds oxygen and stores it

100
Q

Fast twitch muscle fibers

A

Respond rapidly to nervous stimulation. Myosin head have fast enzymes to break down ATP

101
Q

Calmodulin

A

Cal modulus and calcium bind to activate myosin kinase

102
Q

Myosin phosphatase

A

Causes Relaxation of smooth muscle

103
Q

Visceral smooth muscle

A

Sheets of muscle in digestive, reproductive and urinary tracts

104
Q

Multi unit smooth muscle

A

Sheets in blood vessels, small bundles in arrest or pili muscles, iris and single cells in spleen

105
Q

Cardiac muscle

A

Heart only, branching fibers, intercalated disks

106
Q

Sarcopenia

A

Aging, muscle atrophy