Muscular System - Cellular Structure Flashcards
1
Q
Muscle cells are also known as ___.
A
Muscle fibers
2
Q
True or False: Muscle fibers are uninucleated.
A
FALSE. Muscle fibers are multinucleated (have many nuclei).
3
Q
True or False: Muscle fibers tend to be smaller in larger muscles and larger in smaller muscles.
A
FALSE. Smaller muscles = smaller muscle fibers; larger muscles = larger muscle fibers.
4
Q
Where do muscle fibers develop from?`
A
Myoblasts
5
Q
These are converted to muscle fibers as contractile proteins accumulate within their cytoplasm.
A
Myofibrils
6
Q
Muscle cells can range from ___ to ___ in length.
A
1mm - 4cm
7
Q
True or False: Enlargement of muscles is an increase in muscle fiber size rather than number.
A
TRUE. Muscle fibers are amitotic (cannot undergo cell division), so they increase in size rather than dividing.
8
Q
____ bands cause the light bands in skeletal muscle striations, while ____ bands cause the dark striations.
A
I bands; A bands
9
Q
What are the 5 connective tissue coverings of muscle in order from innermost to outermost?
A
External lamina
Endomysium
Perimysium
Epimysium
Fascia
10
Q
What is the cell membrane of the muscle cell?
A
Sarcolemma
11
Q
The sarcoplasm is the muscle cell equivalent of the organelle called the ___.
A
Cytoplasm
12
Q
It is a loose connective tissue with reticular fibers that surrounds groups of myofibrils.
A
Endomysium
13
Q
It is a denser connective tissue surrounding a group of muscle fibers.
A
Perimysium
14
Q
A group of muscle fibers is also called a ____.
A
Fasciculus/fascicle
15
Q
It is a connective tissue that surrounds a group of fascicles.
A
Epimysium
16
Q
What do you call a group of many fascicles?
A
Muscle
17
Q
This connective tissue sheath forms a layer under the skin.
A
Fascia`
18
Q
It holds muscles together & separates them into functional groups.
A
Fascia
19
Q
Aside from muscles, what other body parts does the fascia carry?
A
Nerves, blood vessels, & lymphatic organs
20
Q
The fascia is continuous with connective tissues of ___ and ___.
A
Tendons; periosteum
21
Q
What are the components of the muscle in order from innermost to outermost?
A
Myofilaments, myofibrils, muscle fibers, fascicles, muscle
22
Q
What are the two myofilaments?
A
Actin & myosin
23
Q
Actin & myosin form highly ordered units called ___.
A
Sarcomeres
24
Q
Sarcomeres are joined end to end to form ___.
A
Myofibrils
25
A ____ is composed of many myofibrils grouped together.
Muscle fiber
26
Groups of myofibrils are covered with an outer layer called the ___.
Sarcolemma
27
The ___ is found in between individual muscle fibers.
Endomysium
28
Fascicles are covered by the ___.
Perimysium
29
A muscle is covered by the outermost layer called the___.
Epimysium
30
These nerve cells have axons that extend to skeletal muscle fiber fibers through nerves.
Motor neurons
31
Muscle fibers are surrounded by ___.
Capillary beds
32
___is known as the thin myofilament, while ___ is known as the thick myofilament.
Actin; myosin
33
Actin is ____ in size; while myosin is ___ in size.
8nm; 12nm
34
What theory explains the shortening of muscle during contraction?
Sliding Filament Theory
35
True or False: According to the sliding filament theory, actin and myosin myofilaments change in length during contraction.
FALSE. Actin & myosin do not change in length during contraction.
36
True or False: In the sliding filament theory, actin & myosin myofilaments slide past each other in a way that causes sarcomeres to lengthen.
FALSE. Sliding of actin & myosin causes sarcomeres to shorten.
37
In the sliding filament theory, the ___ & ___ become narrower during contraction, while the ___ remains consistent in length.
I & H zones; A band
38
Once a muscle fiber begins to contract, it will contract maximally (meaning the entire muscle will contract). This is known as the ____.
All or none principle.
39
True or False: In the sliding filament model, actin slides over myosin, while myosin does not move.
TRUE
40
What causes sarcomeres to lengthen during relaxation?
External force
41
What are some external forces that may cause the lengthening of sarcomeres?
Forces produced by other muscles, gravity
42
They are muscles that are primarily responsible for producing a particular movement, such as flexion.
Agonists
43
Agonists are also called ___.
Prime movers
44
Muscles that oppose the action of the agonist are called ___.
Antagonists
45
What types of muscles aid the action of agonists by reducing undesirable/unnecessary movement?
Synergists
46
A special type of synergist that immobilizes the origin of the agonist.
Fixator/fixation muscle
47
A muscle's more movable attachment is called its ___.
Insertion
48
A muscle's fixed/immovable attachment is called its ___.
Origin
49
The junction between a nerve fiber & a muscle fiber is called a ___.
Neuromuscular junction/Myoneural junction
50
During flexion of the elbow, ___ is the agonist, while ___ is the antagonist.
Biceps brachii; triceps brachii
51
During extension of the elbow, ___ is the agonist, while ___ is the antagonist.
Triceps brachii, biceps brachii
52
The nervous system controls muscle contractions via ___.
Action potential
53
Membrane voltage/electric charge difference across membranes.
Resting membrane potential
54
True or False: The inside of the muscle cell is more positive with more potassium, while the outside of the cell is more negative with more sodium.
FALSE. The inside is more negative, while the outside is more positive.
55
What must exist in order for action potential to occur?
resting membrane potential
56
What are two types of ion channels?
Ligand-gated & voltage-gated
57
They are molecules that bind to receptors.
Ligands
58
They are proteins/glycoproteins with a receptor site.
Receptors
59
What is the relationship between the shortening of a sarcomere and the contraction/shortening of a muscle?
Directly proportional
60
Resting membrane potential is maintain by ___.
Na/K Pump
61
Is a neurotransmitter an example of a ligand?
Yes
62
What are the building blocks of myofibrils?
Action & myosin
63
During flexion of the elbow, the biceps brachii ___, while the triceps brachii ___.
Contracts; relaxes
64
During extension of the elbow, the biceps brachii ___, while the triceps brachii ___.
Relaxes; contracts
65
True or False: Acetylcholine is an example of a neurotransmitter.
TRUE
66
Acetylcholinesterase breaks down acetylcholine into what components?
Acetic acid and choline
67
In the muscle cell, what attaches to the receptor in order to open the ligand-gated channels?
Acetylcholine
68
Acetylcholine is released into the muscle fiber by the use of what ion?
Calcium
69
This type of ion channel opens & closes in response to small voltage charges across plasma membrane.
Voltage-gated
70
True or False: Both ligand-gated and voltage-gated channels are specific for one type of ion.
TRUE
71
Action potential is also known as ___.
Impulse
72
What are the two phases of action potential?
Depolarization & repolarization
73
During this phase of action potential, the inside of the sarcolemma becomes less negative.
Depolarization
74
It is the return of resting membrane potential.
Repolarization
75
What restores the resting membrane potential?
Na/K pump
76
It is the spread from one location to another.
Propagate
77
True or False: During propagation, action potential moves along the membrane.
FALSE. Action potential does not move along the membrane; rather, there is new action potential at each successive location.
78
It is formed when an axon terminal rests on an invagination in the sarcolemma.
Synapse
79
What is the presynaptic terminal?
Axon terminal with synaptic vesicles
80
What is the postsynaptic terminal/membrane?
Sarcolemma or skeletal muscle.
81
The postsynaptic membrane is also known as ___?
Motor end-plate
82
What is the space between the axon terminal & the sarcolemma called?
Synaptic cleft
83
True or False: In a synapse, the axon terminal and sarcolemma attach to each other.
FALSE. They do not make contact with each other; there is a gap/space between them.
84
It separates muscle from another muscle
Fascia
85
What is the order of layers of tissue from skin to bone?
Skin
Subcutaneous Tissue
Fascia
Muscle
Peritoneum
86
What are the two synaptic vesicles?
Neurotransmitter & acetylcholinesterase
87
It is a substance released from a presynaptic membrane that diffuses across the synaptic cleft & stimulates/inhibits the production of an action potential in the postsynaptic membrane.
Neurotransmitter
88
It is a degrading enzyme in the synaptic cleft that prevents the accumulation of acetylcholine.
Acetylcholinesterase
89
What are 4 inhibitors of muscle contraction?
Neuromuscular-blocking drugs
Presynaptic inhibition
Postsynaptic inhibition
Non-depolarizing blocking agents
90
What prevents the synthesis/release of acetylcholine from the synaptic terminal?
Presynaptic inhibition
91
What acts at the neuromuscular junction to prevent/reduce action potential production?
Neuromuscular-blocking drugs
92
What prevents the production of action potential in the postsynaptic membrane?
Postsynaptic Inhibition
93
They block the movement of ions through ion channels in the postsynaptic membrane.
Non-depolarizing blocking agents
94
How can non-depolarizing blocking agents block the process of muscle contraction?
- Binding to Ach receptors in the Na+ channel (blocks Ach from binding to receptor)
- Blocking Na+ channel (prevents Na+ movement into muscle fiber)
95
What is an example of a presynaptic inhibitor?
Botulinum toxin (BOTOX)
96
Improper dosage of BOTOX may lead to what rare condition?
Botulism
97
What is an example of a non-depolarizing blocking agent?
Curare
98
It is the contraction of a muscle as a result of one or more muscle fibers contracting.
Muscle twitch
99
Muscle contraction is measures as___.
Force/tension
100
How long does muscle contraction take to occur?
Up to 1 second
101
What are the three phases of muscle contraction?
Lag/latent
Contraction
Relaxation
102
It is the contraction of equal force in response to each action potential.
All-or-None Law
103
What are the three levels of stimulus strength?
- Sub-threshold/Submaximal Stimulus
- Threshold/Maximal Stimulus
- Supramaximal Stimulus
104
In this stimulus, there is no action potential & no contraction.
Sub-threshold stimulus
105
It is the smallest amount of stimulation/action potential needed in order to produce a contraction.
Threshold stimulus
106
This stimulus strength has action potential and a contraction equal to that with threshold stimulus.
Supramaximal stimulus
107
Comprised of a single motor neuron & all muscle fibers innervated by it.
Motor unit
108
True or False: There must be relaxation of a muscle fiber before a second action potential can stimulate a second contraction.
FALSE. Relaxation is not required for stimulating succeeding contractions.
109
What is the relationship between frequency or action potential & frequency of contractions?
Directly proportional (as frequency of action potential increases, frequency of contraction increases)
110
Muscle fibers partially relax between contractions.
Incomplete tetanus
111
No relaxation between contractions.
Complete tetanus
112
Muscle tension increases as contraction frequencies increase.
Multiple-wave summation
113
What are the three types of muscular contractions?
Isometric, isotonic, muscle tone
114
In this type of muscle contraction, there is no change in length of muscle, but tension increases during contraction.
Isometric
115
In this type of muscle contraction, there is change in length but tension is constant.
Isotonic
116
What are the two types of isotonic muscle contractions?
Concentric & eccentric
117
In this type of isotonic contraction, tension is so great that t overcomes opposing resistance and muscle shortens.
Concentric
118
This type of isotonic contraction enables muscles to resist an increase in length.
Eccentric
119
It is the constant tension by muscles for a long period of time.
Muscle tone
120
Where can isometric contractions be seen?
Postural muscles of the body
121
Muscles holding the spine erect while a person is sitting/standing is an example of what type of contraction?
Isometric
122
What type of contraction is used when typing using a computer keyboard?
Isotonic
123
The raising of a weight during a bicep curl utilizes what contraction?
Concentric
124
When a person slowly lowers a heavy weight, what contraction is displayed?
Eccentric
125
True or False: Asynchronous contractions of motor units produce smooth, steady muscle contractions.
TRUE
126
It is the decreased capacity to work & the reduced efficiency of performance.
Fatigue
127
What are the three types of fatigue?
Psychological, muscular, synaptic
128
This type of fatigue depends on the emotional state of the individual.
Psychological fatigue
129
This type of fatigue results from ATP depletion.
Muscular fatigue
130
This fatigue occurs in the neuromuscular junction.
Synaptic
131
How does synaptic fatigue occur?
Lack of acetylcholine
132
A burst in activity of a tired athlete shows how ___ fatigue can be overcome.
Psychological
133
Fatigue in the lower limbs of marathon runners or the upper & lower limbs of swimmers are examples of ____ fatigue.
Muscular
134
This type of fatigue is rare and occurs only under extreme conditions.
Synaptic
135
What provides immediate energy for muscle contractions?
Adenosine triphosphate (ATP)
136
ATP can be produced from what 3 sources?
Creatine phosphate, anaerobic respiration, and aerobic respiration
137
It stores energy during resting conditions to synthesize ATP.
Creatine phosphate
138
Adenosine diphosphate (ADP) and Creatine phosphate react to produce ___.
Creatine and adenosine triphosphate.
139
What enzyme catalyzes the reaction between creatine phosphate and ADP?
Creatine Kinase
140
This energy source occurs in absence of oxygen and results in breakdown of
glucose.
Anaerobic respiration
141
What are the products of anaerobic respiration?
ATP and lactic acid
142
This energy source requires oxygen and breaks down glucose.
Aerobic respiration
143
What two energy sources break down glucose?
Anaerobic and aerobic respiration
144
What are the products of aerobic respiration?
ATP, carbon dioxide and water
145
True or False: Aerobic respiration is more efficient than anaerobic respiration.
TRUE
146
What are the two types of muscle fibers in terms of speed of muscle twitch?
Slow-twitch oxidative and fast-twitch
147
This type of muscle fiber contract more slowly, are smaller in diameter, better blood supply, have more mitochondria, are more fatigue-resistant, and have a large amount of myoglobin.
Slow-twitch oxidative
148
Slow-twitch fibers are also called oxidative because they carry out what energy source?
Aerobic respiration
149
A dark pigment which binds oxygen & acts as a muscle reservoir for oxygen when blood does not supply adequate amount.
Myoglobin
150
This type of muscle fiber can respond rapidly to nervous stimulation, contain myosin that can break down ATP
more rapidly than that in Type I, has less blood supply, and fewer and smaller mitochondria.
Fast-twitch
151
Fast-twitch fibers adapted to perform what energy source?
Anaerobic respiration
152
Where can slow-twitch fibers be found?
Postural muscles, more in lower than upper limbs, dark meat of chicken.
153
Where can fast-twitch fibers be found?
Lower limbs in sprinter, upper limbs of most people, white meat in chicken
154
The functions of this type of fiber include maintenance of posture & performance in endurance activities.
Slow-twitch
155
The functions of this type of fiber include rapid, intense movements of short duration.
Fast-twitch
156
What are the effects of exercise on muscle fibers?
Change in size
157
What are the two forms of fast twitch fibers?
Oxidative and glycolytic forms
158
True or False: In exercise, weight lifting enlarges fast-twitch & aerobic training enlarges slow-twitch.
TRUE
159
What is the distribution of fast-twitch and slow-twitch muscle fibers?
Most muscles have both but varies for each muscle.
160
What are the two types of change in muscle size in relation to exercise?
Hypertrophy and atrophy
161
It is an increase in muscle size.
Hypertrophy
162
Is is a decrease in muscle size.
Atrophy
163
Besides size, what also increases during hypertrophy?
myofibrils, nuclei (due to fusion of satellite cells), strength
*reverse is true for atrophy
164
True or False: Cells can die from atrophy.
TRUE. Only in severe situations.
165
What are the effects of aging on skeletal muscles?
- Reduced muscle mass
- Increased time for muscle to contract in response to nervous stimuli
- Reduced stamina
- Increased recovery time
- Loss of muscle fibers
166
Attach muscles to bones.
Tendons
167
A very broad tendon.
Aponeurosis
168
Muscle end attached to more stationary of two bones.
Origin or head
169
Muscle end attached to bone with greatest movement.
Insertion
170
Largest portion of the muscle between origin and
insertion
Belly
171
Muscles that work together to cause a movement
Synergists
172
Plays major role in accomplishing movement.
Prime mover/agonist
173
Muscle causing an action when contracts.
Prime mover/agonist`
174
A muscle working in opposition to agonist.
Antagonist
175
Stabilize joint/s crossed by the prime mover.
Fixators
176
What are the four patterns of fibers in the muscle?
Circular, convergent, parallel, pennate
177
Fibers arranged concentrically around an opening.
Circular muscle
178
Triangular muscle with common attachment site.
Convergent
179
Functions as a sphincter to close a passageway or opening.
Circular
180
Direction of pull of muscle can be changed.
Convergent
181
Does not pull as hard as equal-sized parallel muscle.
Convergent
182
Fascicles are parallel to the long axis of the muscle.
Parallel
183
Muscle body has one or more tendons.
Pennate
184
Body of muscle increases in diameter with contraction.
Pennate
185
Fascicles at oblique angle to tendon.
Pennate
186
High endurance, not very strong
Parallel
187
Pulls harder than a parallel muscle of equal size.
Pennate
188
What are the three types of pennate muscles?
Unipennate, bipennate, multipennate
189
What are some examples of circular muscles?
Orbits, mouth (obicularis oris), anus
190
What is an example of a convergent muscle?
Pectoralis major
191
What are some examples of parallel muscles?
Rectus abdominis or sartorius
192
This type of muscle has fibers same side of tendon.
Unipennate
193
This type of muscle has fibers on both side (interosseous).
Bipennate
194
This type of muscle has tendon branches within the muscle.
Multipennate
195
Give an example of a unipennate muscle.
Extensor digitorum
196
Give an example of a bipennate muscle.
Rectus femoris
197
Give an example of a multipennate muscle.
Deltoid
198
Muscles are named according to ___.
– Location
– Size
– Shape
– Orientation of fasciculi
– Origin and insertion
– Number of heads
– Function
199
Muscle contractions are a pull or force by relative positions of ___
Lever, fulcrum, and weight/resistance
200
It is a shaft or bone.
Lever
201
It is a pivot joint/joint.
Fulcrum
202
How many classes of levers are there?
3 (Class I, Class II, Class III)
203
In this class of lever, the fulcrum is between force and weight there is a seesaw or head movement.
Class I
204
In this class of lever, the weight is between fulcrum and pull wheelbarrow, standing
on toes.
Class II
205
In this class of levers, the pull located between the fulcrum and weight.
Class II
206
What is the most common class of levers?
Class III
207
A person using a shovel is an example of what class of levers?
Class III
208
Standing on toes is an example of what class of levers?
Class II
209
Muscle ache is known as ___.
Myalgia
210
What are the two types of range of motion?
Passive and active
211
Passive range of motion prevents___?
Contractures (shortening & hardening of muscles)
212
Active range of motion prevents ___?
Atrophy
