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Muscle Physiology > Muscle > Flashcards

Muscle Flashcards

(107 cards)

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0
Q

Contractility

A

The ability of muscle to shorten forcefully

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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

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2
Q

Excitability

A

The capacity of muscle to respond to a stimulus

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3
Q

Extensibility

A

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

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4
Q

Elasticity

A

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

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5
Q

Types of muscle

A

Skeletal, smooth, cardiac

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6
Q

Skeletal muscle

A

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

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7
Q

Smooth muscle

A

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

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8
Q

Cardiac muscle

A

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

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9
Q

Skeletal muscle fibers

A

Skeletal muscle cells

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10
Q

Fasciculi

A

Visible bundles of muscle

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11
Q

Perimyseum

A

Connective tissue layer surrounding fasciculi

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12
Q

Epimysium

A

Surrounds entire muscle. Dense collagenous connective tissue.

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13
Q

Fascia

A

General term for connective tissue sheets within the body

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14
Q

Muscular fascia

A

Superficial to epimysium, separates and compartmentalizes individual muscle groups

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15
Q

Motor neurons

A

Specialized nerve cells that stimulate muscles to contract

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16
Q

Myoblasts

A

Muscle fibers develop from less mature, multinucleated cells called myoblasts

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17
Q

Hypertrophy

A

Enlargement

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18
Q

Sarcolemma

A

Plasma membrane of a muscle fiber. Two layers

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19
Q

External lamina

A

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

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20
Q

Endomysium

A

Second layer of sarcolemma. Thicker layer

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21
Q

Transverse (t) tubules

A

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

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22
Q

Sarcoplasmic reticulum

A

Endoplasmic reticulum in muscle cells

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23
Q

Sarcoplasm

A

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

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24
Myofibrils
Within sarcoplasm. Bundles of protein filaments I
25
Myofilaments
Actin and myosin
26
Sarcomeres
Actin and myosin myofilaments highly ordered units
27
Actin Myofilaments are composed of
Two strands fibrous actin (f actin) tropomyosin molecules and troponin molecules
28
Globular actin
G actin. Active site where myosin molecules bind during contraction
29
Myosin molecules are
Myosin heavy chains to make a rid portion and myosin heads
30
Cross-bridges
Myosin heads bind to active sites on actin to form cross bridges
31
Myosin heads
ATPase enzymes which break down ATP and release energy.
32
ATP
Adenosine triphosphate
33
Z disk
Network of protein forming a dislike structure for the attachment of actin myofilaments
34
I band
Isotropic band. Includes Z disk, and extends from one side to the other. Only actin filaments
35
A band
Anisotropic band. Extends the length of myosin filaments within a sacromere
36
H zone
Actin and myosin filaments do not overlap and only myosin is present
37
M line
Middle of H zone. Chain in the middle that holds myosin in place
38
Titin
Largest protein. Attaches to z disk to m line
39
Ligand-gated ion channels
Ion channels that open as a result of a neurotransmitter
40
Mv
Millivolts. Measures resting membrane potential
41
Depolarization phase
Brief period during which further depolarization occurs and inside of cell becomes positively charged
42
Repolarization phase
Return to resting value
43
All or nothing principle
If depolarization reaches threshold, permeable changes proceed without stopping
44
Propagate
Action potentials can travel across plasma membrane to adjacent location
45
Neuromuscular junction
Synapse
46
Presynaptic
Axon terminal
47
Synaptic cleft
Space between presynaptic terminal and muscle fiber
48
Postsynaptic membrane
Motor end plate. Muscle area of junction
49
Synaptic vesicles
Spherical sacs on presynaptic terminal. Contain acetylcholine
50
Acetylcholine
ACh. Neurotransmitter that alters post synaptic cell
51
Acetylcholinesterase
Breaks down acetylcholine and keeps it from accumulating in the synaptic cleft.
52
Excitation-contraction coupling
Action potential causes contraction
53
Terminal cisternae
Near t tubules, the sarcoplasmic reticulum is enlarged to form terminal cisternae
54
Triad
A t tubule and two adjacent terminal cisternae together
55
Cross bridge cycling
During contraction, myosin molecules undergo cross bridge formation and return of position many times
56
Power stroke
Movement of myosin molecule while cross bridge is attached
57
Recovery stroke
Return of myosin head to its original position after cross bridge
58
Muscle twitch
Single, brief contraction. Does not last long enough to perform any work
59
Lag phase
Time between the application of stimulus to motor neuron and muscle contraction
60
Contraction phase
Time when contraction occurs
61
Relaxation phase
When relaxation occurs
62
Motor unit
Single | Motor neuron and all the muscle fibers it innervates
63
Graded
Strength of muscle contractions varies from weak to strong. Wholesales respond.
64
Summation
Involves increasing the force of contraction of the muscle fibers
65
Recruitment
Increasing number of muscle fibers contracting
66
Treppe
A muscle fiber, when stimulated in rapid succession, contracts with greater force with each subsequent stimulus
67
Multiple motor unit summation
Relationship between increasing stimulus strength and increased number of contracting motor units. More motor units with more force of contraction
68
Subthreshold stimulus
Not strong enough to cause an action potential or contraction
69
Threshold stimulus
Strong enough to produce an action potential in a single motor unit axon
70
Submaximal stimuli
Produce action potentials in axons of additional motor units
71
Maximal stimulus
Produces action potentials in the axons of all the motor units of that muscle
72
Tetanus
Frequency of action potentials in skeletal muscle increases the frequency of contraction also increases until a period of sustained contraction
73
Incomplete tetanus
Muscle fibers partially relax between the contractions
74
Complete tetanus
No relaxation between contractions
75
Multiple wave summation
When the frequency of contractions increases, the tension produced is called multiple wave summation
76
Active tension
Force applied to an object to be lifted when a muscle contracts
77
Active tension curve
Muscle length plotted against the tension produced by the muscle in response to maximal stimuli
78
Passive tension
Tension applied to the load when a muscle stretches but is not stimulated
79
Total tension
The sum of active and passive tension
80
Isometric contractions
The length of the muscle does not change but the amount of tension increases during contraction
81
Isotonic contractions
The amount of tension produced by the muscle is constant during contraction but the length of the muscle changes
82
Concentric contractions
Isotonic contractions in which tensions in the muscle is great enough to overcome the opposing resistance and the muscle shortens
83
Eccentric contractions
Isotonic contractions in which tension is maintained in a muscle to increase in length. Lowers heavy weight
84
Muscle tone
Constant tension produced by muscles for long periods of time
85
Fatigue
decreased capacity to do work and the reduced efficiency of performance that normally follows a period of activity
86
Psychological fatigue
Involved central nervous system, individual perceives that no more work is possible
87
Muscular fatigue
Calcium ion imbalances as ATP levels drop. Cross bridges cannot function properly.
88
Synaptic fatigue
Neuromuscular junction. High frequency of acetylcholine without enough synthesizing.
89
Physiological contracture
In cases of extreme fatigue. Muscles are not capable of contraction or relaxing. No ATP
90
Rigor Mortis
Development of ridged muscles several hours after death, similar to physiological contracture
91
Creative phosphate
Accumulates in muscle fibers where it stores energy that can be used to synthesize ATP
92
Anaerobic respiration
Breakdown of glucose to yield ATP and lactic acid
93
Glycolysis
Glucose molecule is broken down into two molecules of pyruvic acid. Lactic acid diffuses into bloodstream
94
Aerobic respiration
Requires oxygen and breaks down glucose to produce ATP carbon dioxide and water.
95
Oxygen deficit
Insufficient oxygen consumption relative to increased activity.
96
Recovery oxygen consumption
Elevated oxygen levels after exercise has ended
97
Slow twitch oxidative muscle fibers
Contract more slowly, better blood supply, more mitochondria and more fatigue resistant
98
Myosin ATPase
Enzymes on the myosin heads responsible for the breakdown of ATP
99
Myoglobin
Dark pigment similar to hemoglobin in RBC. Binds oxygen and stores it
100
Fast twitch muscle fibers
Respond rapidly to nervous stimulation. Myosin head have fast enzymes to break down ATP
101
Calmodulin
Cal modulus and calcium bind to activate myosin kinase
102
Myosin phosphatase
Causes Relaxation of smooth muscle
103
Visceral smooth muscle
Sheets of muscle in digestive, reproductive and urinary tracts
104
Multi unit smooth muscle
Sheets in blood vessels, small bundles in arrest or pili muscles, iris and single cells in spleen
105
Cardiac muscle
Heart only, branching fibers, intercalated disks
106
Sarcopenia
Aging, muscle atrophy

Muscle Physiology (3 decks)

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