Muscular System Flashcards
(171 cards)
1
Q
What are the six functions of the muscular system?
A
- body movement
- maintenance of posture
- protection and support (ex. abdominal wall)
- movement of materials (blood, air, food)
- heat production (shivering)
- communication (verbal and non-verbal)
2
Q
What is the function of muscle tissue?
A
contract to generate movement
3
Q
What are three types of muscle tissue?
A
smooth, cardiac, and skeletal
4
Q
What is the name of muscle cells?
A
myocytes
5
Q
Smooth muscle tissue characteristics
A
- tapered (pointy ends)
- non-striated
- uni-nucleated
6
Q
Smooth muscle tissue location
A
organ walls
7
Q
Smooth muscle tissue: voluntary or involuntary?
A
involuntary
8
Q
Cardiac muscle tissue characteristics
A
- has branches
- striated
- 1-4 nuclei
9
Q
Cardiac muscle tissue location
A
heart
10
Q
Cardiac muscle tissue: voluntary or involuntary?
A
involuntary
11
Q
Skeletal muscle tissue characteristics
A
- long
- striated
- multi-nucleated
12
Q
Skeletal muscle tissue location
A
skeleton
13
Q
Skeletal muscle tissue: voluntary or involuntary?
A
voluntary
14
Q
What is another name for skeletal muscle tissue?
A
muscle fibers
15
Q
What is a muscle fiber?
A
a cell
16
Q
Skeletal muscle tissue is responsible for what?
A
shivering
17
Q
Thousands of myocytes =
A
muscle fibers
18
Q
Skeletal muscle composition?
A
- thousands of myocytes
- blood vessels
- nerves (sensory + motor)
19
Q
What are the three layers of connective tissue surrounding skeletal muscle?
A
- epimysium
- perimysium
- endomysium
20
Q
Epimysium
A
around each muscle
21
Q
Perimysium
A
around each fascicle
22
Q
Endomysium
A
around each muscle fiber
23
Q
Fascicle
A
a bundle of skeletal muscle fibers surrounded by perimysium, a type of connective tissue
24
Q
What does fascicle mean?
A
bundle
25
What happens when the epimysium, perimysium, and endomysium, merge together?
forms tendons
26
What are the seven characteristics used to name skeletal muscle?
- action
- body region
- attachment
- orientation of muscle fibers
- shape
- size
- # of muscle heads
27
Skeletal muscle is what?
an organ
28
What is another word for muscle heads?
cephal
29
What are the actions of skeletal muscle?
- adductor/abductor
- flexor/extensor
30
Body region: Cervicis
neck
31
Body region: Oris
mouth
32
Body region: Brachial
arm
33
Body region: Carpi
wrist
34
Body region: Femoris
thigh
35
Body region: Profundus
forearm/antebrachial
36
Body region: Superior
towards the head
37
Skeletal muscle naming: attachment
intercostal
38
What does intercostal mean?
between the ribs
39
What are the three orientations of skeletal muscle?
- rectus
- oblique
- orbicularis
40
Rectus
straight
41
Oblique
diagonal/slanting
42
Orbicularis
circular
43
Where can orbicularis skeletal muscle be found?
the mouth and eyes
44
What are the shapes of skeletal muscle?
- deltoid
- quadratus
- trapezius
- teres
45
Deltoid
triangle
46
Quadratus
square
47
Trapezius
trapezoid
48
Teres
rounded
49
What are the sizes of skeletal muscle?
- longus/brevis
- major/minor
- latissimus
-minimus/maximus/medius
50
Longus
long
51
Brevis
short
52
Major
largest
53
Minor
smallest
54
Medius
medium
55
What does "fund-" mean?
foundation/al or base
56
What does "rect-" mean?
straight
57
Orientation
which way something is going
58
What does "orbi-" mean?
circle
59
What does "brev-" mean
brief
60
Latissimus
broadest
61
Muscles only what?
pull
62
What is the rule of thumb for minimus, maximus, and medius?
if you have one then all three exist
63
What are the possible number of cephals or muscle heads of the skeletal muscle?
- bicep
- tricep
-quadricep
64
Bicep
2
65
Tricep
3
66
Quadricep
4
67
How are muscle fibers (skeletal muscle cells) formed?
embryonic myoblasts fuse together to form muscle fibers
68
Satellite cell function
muscle repair/regeneration
69
What type of tissue uses "myo-" and "sarco-"?
muscles
70
Sarcolemma
muscle cell's plasma/cell membrane
71
Sarcoplasm
muscle cell's cytoplasm
72
Sarcoplasmic reticulum (SR)
muscle cell's endoplasmic reticulum
73
Myofibril
contractile organelle
74
Sarcolemma composition
lipid bilayer + imbedded proteins and carbs
75
The sarcolemma is what?
semi-permamble
76
Resting membrane potential
the difference in charges across the membrane when at rest
77
What are the charges of the sarcolemma?
+ on the outside and - on the inside
78
What is the resting potential for myocytes?
90 mV
79
What does mV mean?
millivolt
80
What are the reasons for the difference in charges of the sarcolemma?
-Na-K ion pump
- K+ leak channel (H to L)
81
What do Na-k ion pumps do to the sarcolemma?
- move more + outside
- creates a concentration gradient of ions
82
What does K+ leak channels do to the sarcolemma?
addxs "+" outside
83
What is the rule of Na-K ion pumps?
three sodium out, two potassium in
84
What are the invaginations created by the sarcolemma called?
t-tubules
85
T-tubules function
deliver the signal into the interior
86
The sarcoplasmic reticulum forms what?
terminal cisternae on both sides of t-tubules
87
Terminal cisternae function
store Ca2+ (signaling ion)
88
About 80% of sarcoplasm is taken up by what?
hundreds of myofibrils
89
Myofibrils are made up of what?
thin and thick filaments
90
Sacromeres
filaments organized into repreating units
91
Filaments are organized into sarcomeres for what function?
contraction
92
Sarcomeres stretch from what to what?
z disc to z disc
93
Thick filament
a bundle of the contractile protein myosin
94
What are the two parts of a thick filament?
the actin binding site and the ATP binding site
95
What is the function of the actin binding site in thick filaments?
attachment
96
What is the function of the ATP binding site in thick filaments?
energy
97
What are the three characteristics of thin filaments?
- actin contractile protein with myosin binding sites
- tropomyosin
- troponin
98
Tropomyosin
a regulatory protein (cover actin)
99
Troponin
a regulatory protein (with Ca2+ binding sites)
100
Regulation of skeletal muscle contraction is done by what?
- motor neurons
- motor unit
- neuromuscular junction (synapse)
101
What initiates skeletal muscle contraction?
motor neurons
102
Motor unit
each motor neuron and the multiple fibers it controls
103
Neuromuscular junction
location where a motor neuron innervates a skeletal muscle cell/fiber
104
Synaptic knob
houses the synaptic vesicles and neurotransmitter acetylcholine (ACh)
105
Synaptic cleft
fluid filled space separating the synaptic knob from the motor end plate
106
Motor end plate
heavily folded sarcolemma with ACh receptors (receiving end for ACh)
107
What are the three steps of the physiology of skeletal muscle contraction?
- Excitation
- Excitation- Contraction coupling
- Cross bridge cycling
108
Where does excitation occur?
at the neuromuscular junction
109
What is the first step of excitation?
a nerve signal delivered by a motor neuron triggers the entry of Ca2+ into the synaptic knob through the gated Ca2+ channels
110
What is the second step of excitation?
There (the synaptic knob) Ca2+ binds to the synaptic vesicle and triggers them to bind with the plasma membrane. ACh is then released into the synaptic cleft
111
What mechanism is used to release or diffuse ACh into the synaptic cleft?
exocytosis
112
What is the third step of excitation?
ACh diffuses across the cleft and binds to the ACh receptor at the motor end plate
113
What are the three phases of contraction coupling (where/when these are taking place)?
- Motor end plate
- Edge of the motor plate
- When action potential reaches the t-tubules
114
Motor end plate phase
ACh bonds to the ACh receptor causing:
- chemically gated channel opens
- fast diffusion of Na+ in the cell
- inside becomes more "+"
115
What is the ACh receptor in the motor end phase?
chemically gated ion channel
116
What is the motor end plate phase called?
end plate potential (EPP)
117
Edge of the motor plate phase
altered membrane potential (EPP)
- voltage gated Na channel opens
-fats diffusion of Na+ in the cell
- action potential
- muscle impulse
118
Action potential
local reversal of charges
119
Muscular impulse
wave of voltage gated Na+ channels opening along the sarcolemma and into the t-tubules
120
When action potential reaches t-tubules phase?
opening of voltage gated Ca2+ channels in the terminal cisternae of the SPR
- Ca2+ diffuses into the sarcoplasm and reaches sarcomere
121
What are sarcomeres?
contractile units
122
What are the three kinds of channels involved in the physiology of skeletal muscle contraction?
- chemically gated ion channels
- voltage gated Na channels
- voltage gated Ca2+ channels
123
What triggers cross-bridge cycling?
Ca2+ comes in binds to troponin, shifts tropomyosin thus opening myosin binding sites.
124
Where does crossbridge cycling take place?
in the sarcomeres
125
What are the four steps of cross-bridge cyclying?
1. "attach"
2. "pull"
3. "release"
4. "reset"
126
Attach =
Cross-bridge formation
127
Pull =
Power stroke
128
Release =
Release of myosin head
129
Reset =
Reset myosin head
130
Cross-bridge formation
myosin heads bind to the myosin binding sites forming a crossbridge
131
Power Stroke
The myosin head swivels toward the center of the sarcomere, pulling the thin filaments.
132
What is released during the power stroke?
ADP and Pi (phosphate)
133
Release of myosin head
ATP binds to the myosin head, which causes the release of the myosin head from actin
134
Reset of myosin head
ATP is split into ADP and Pi (phosphate) providing the energy to reset the myosin head
135
What is used to "cock" the myosin head while at rest?
energy/ATP
136
Stimulation above the threshold results in what?
a muscle generates force
137
What is muscle tension?
when a muscle generates force
138
What is a twitch?
a muscles response to a single stimulation
139
Latent (lag) period
a short delay from the time when the action potential reaches the muscle until tension can be observed in the muscle
140
What are the three phases or periods of a twitch?
a latent period, contraction phase, and a relaxation phase
141
Muscle tone
resting tension
142
Why is muscle tension never at zero?
muscle tone
143
What four factors influence performance of a muscle?
- stimulus intensity
- stimulus frequency
- effect of sustained exercise
- effect of aging
144
Intensity =
how strong
145
What happen when the intensity is increased?
- the number of motor units recruited increases
- the muscle tension increases
146
Max contraction
when all the motor units are recruited, the maximum possible tension is achieved
147
Graded response
a muscle ability to produce varying levels of force based on our needs
148
Frequency =
how often
149
Frequency: <10 per second
a twitch each time
150
Frequency: <10-20 per second
build up of Ca2+ resulting in treppe
151
Treppe
The muscle tension increases in a graded manner that to some looks like a set of stairs (step wise)
152
Frequency: 30-40 per second
wave summation and incomplete tetany occur
153
Wave summation
occurs when stimulations are delivered to a muscle fiber faster than it is able to completely relax.
154
Frequency: > 50 per second
fused contraction and complete tetany occur
155
Incomplete tetany
quivering at max contraction
156
What happens if 50 twitches per second continues beyond complete tetany?
the muscle fatigues
157
Fused contraction/complete tetany
when there is no relaxation of the muscle fibers between stimuli and it occurs during a high rate of stimulation; strongest single-unit twitch in contraction.
158
What are the two outcomes of sustained exercise?
Hypertrophy or hyperplasia
159
Hypertrpohy
an increase in fiber size as the result of increase in the amount of mitochondria, myofibrils, and glycogen reserve
160
Hyperplasia
increase in the number of fibers (cells)
161
Hyperplasia is what?
limited
162
Hypertrophy and hyperplasia result in what?
increased muscle tension
163
Lack of muscle activity results in what?
atrophy
164
Atrophy
decrease in fiber size and power
165
Prolonged inactivity results in what?
fibrosis
166
Fibrosis
muscle tissue converts to connective tissue
167
Effects of aging
- sarcopenia
- injury recovery
- fibrosis
168
Sarcopenia
- decrease in fiber number/diameter
- decrease in blood circulation
- decrease in power of skeletal muscles
169
Injury recovery with aging
decrease in the number of satellite cells
170
Fibrosis causes what?
decrease in flexiblity
171
What does a decrease in flexibilty cause?
restriction of movement and circulation
