Chapter 9 - Muscles Flashcards
(124 cards)
0
Q
Muscular tissue accounts for _____ of total body mass
A
45%
1
Q
The scientific study of muscles is known as ____
A
Myology
2
Q
Does most of the work generated by the body
A
Muscles
3
Q
Functions of muscles
A
- Maintain posture and body position
- Movement
- Heat production
- Guard orifices
- Support visceral organs
4
Q
Four properties of muscle tissue
A
- Excitability
- Contractility
- Extensibility
- Elasticity
5
Q
The ability to receive and respond to electrical or chemical stimuli
A
Excitability
6
Q
The ability to shorten forcibly when stimulated
A
Contractility
7
Q
The ability to be stretched forcibly when stimulated
A
Extensibility
8
Q
Ability to return to original shape after being stretched
A
Elasticity
9
Q
Muscles are ____
A
Organs
10
Q
Tissue types in muscles
A
- Connective
- Arteries/Veins
- Nerves
- Lymphatics
- Contractile muscle cells
11
Q
Seven skeletal muscle characteristics
A
- Attaches to bone, skin, or fascia
- Striated with light and dark bands
- Voluntary control
- Long, thin and multi-nucleated fibers
- Arranged into packages that attach to and cover the bony skeleton
- Contracts rapidly, but tire easily
- May exert great force
12
Q
One muscle cell = ?
A
One fiber
13
Q
Main portion of a muscle
A
Belly (Gaster)
14
Q
Muscle structure
A
- Belly is attached to tendons
- Tendons are attached to bone
15
Q
- Dense irregular CT around muscle
- Holds it in place and separates it from other muscles
A
Deep fascia
16
Q
Loose CT beneathskin, surrounds several muscles
A
Subcutaneous fascia
17
Q
Skeletal muscle organization
A
- Many muscle fibers are bundled together into groups called fascicles
- 10-100 muscles cells (fibers)
- Several fascicles make up a muscle
18
Q
Three layers in skeletal muscle CT
A
- Epimysium
- Perimysium
- Endomysium
19
Q
Surrounds the whole muscle
A
Epimysium
20
Q
Surrounds fascicles
A
Perimysium
21
Q
Separates individual muscle fibers (cells)
A
Endomysium
22
Q
All connective tissue extends beyond the muscle belly to form the _____
A
Tendon
23
Q
Tendons may form thick flattened sheets called
A
Aponeuroses
24
Embryonic cells that fuse to form muscle fibers
Myoblasts (Thats why they are so long and multinucleate)
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Myoblasts that do not fuse become ___
Myosatellite cells
26
Assist in repair of damaged cells
Myosatellite cells
27
Three components to fiber structure
1. Sarcoplasm
2. Sarcolemma
3. Transverse (T) tubule
28
Fiber cytoplasm
Sarcoplasm
29
Plasma membrane of a fiber
Sarcolemma
30
Extensions of the sarcolemma into the sarcoplasm
Transverse (T) tubule
31
Contractile organelles that extend the length of fiber
Myofibrils
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Myofibrils are surrounded by the ____
Sarcoplasmic reticulum
33
Characteristics of sarcoplasmic reticulum
- Similar to ER
| - Contains calcium ions
34
The functional unit of a myofibril is called a ____
Sarcomere
35
What are sarcomeres made of?
Thick and thin filaments
36
What are thick filaments made of?
Myosin
37
Characteristics of myosin
1. Twisted protein with globular heads
2. 1.6 um long
3. 500/thick filament
38
Two components to thin filaments
1. Actin
| 2. Regulatory proteins
39
- Structural protein
| - Coiled "beads"
Actin
40
Allow and prohibit attachment between actin and myosin
Regulatory proteins
41
Two regulatory proteins in the thin filaments
1. Tropomyosin
| 2. Troponin
42
Causes the striated appearance of muscle
Sarcomere "bands"
43
Four bands in sarcomere with their meanings
1. A band - entire thick filament
2. I band - only thin filaments
3. H band - only thick filaments
4. Zone of overlap - both filaments
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Divide and flank the sarcomere
Sarcomere "lines"
45
Two sarcomere lines
1. Z line
| 2. M line
46
- The end of the sarcomere
- Made of actinin proteins
- Anchor thin filaments
Z line
47
- Middle of the sarcomere
| - Stabilize thick filaments
M line
48
Three structural proteins
1. Titin
2. Nebulin
3. Actinin
49
- Anchors a thick filament to a Z line
| - Accounts for elasticity and extensiblity
Titin
50
- Holds F actin together on thin filaments
Nebulin
51
Makes up Z line
Actinin
52
As the actin slides over the myosin
- Zone of overlap enlarges
- H bands shrinks
- I band shrinks
- A band remains the same
- The Z line moves closer to the A band
53
Six components to neuromuscular junctions
1. Motor unit
2. Neuromuscular junction
3. Synaptic terminal
4. Motor end plate
5. Synaptic cleft
6. Neurotransmitters
54
Neuron and all muscle cells stimulated by the nueron
Motor unit
55
Point of contact between the neuron and the muscle
Neuromuscular junction
56
End of axon that contacts motor end plate
Synaptic terminal
57
Point on muscle fiber that contacts synaptic terminal
Motor end plates
58
Gap between two synaptic terminals
Synaptic cleft
59
Chemical released into that gap
Neurotransmitters
60
When chemicals are released into the gap between the synaptic terminal
Acetylcholine (Ach)
61
Events of muscle contraction
1. Ach stored in synaptic vesicles
2. Impulses reaches end of neuron --- ach released
3. Ach crosses gap and binds to receptors
4. Impulse travels through motor end plate down T-tubles to SR
5. Ca2+ ions diffuse out of SR into sarcoplasm
6. Ca2+ exposes the active site
7. Myosin then binds to active site
8. ATP is used and contraction occurs
9. Contraction continues as long as Ca2+ concentration is high
62
Explain how the muscle moves due to to using ATP
- The myosin head attaches to at binding site on the actin
- ATP causes the myosin to flex and pull on the actin
- The thin filaments slide inward
63
Explain the events of muscle relaxation
- Ach decomposed by acetylcholinesterase
- Ca ions transported back to SR
- Actin and myosin links broken
- Cross bridges move back
- Active site is blocked once again
64
How is tension produced by a muscle determined?
- The frequency of stimulation
| - Number of motor units stimulated
65
All fibers in a motor unit fully contract if stimulated
All or None Law
66
Steady increase in tension by increasing the number of contracting motor unit
Recruitment
67
Muscle never begins to relax, continuous fused contraction
Tetanus
68
What is muscle tone?
- Motor units contract randomly
| - Tension, but no movement
69
What can muscle tone do?
- Stabilize joints
- Holds objects in place
- Maintain posture
70
Constant, exhaustive stimulation increases the number of organelles/proteins in a fiber
Hypertrophy
71
What does hypertrophy do?
```
Increase:
Mitochondria
Glycolytic enzyme reserves
Myofibrils
Filaments within myofibrils
```
72
Do muscle fibers reproduce?
No you idiot, why would they?
73
Overall enlargement of the muscles is do to what?
Hypertrophy
74
- Lack of constant motor neuron stimulation reduces organelles and proteins
- Reversible if fiber is not dead
```
Due to:
Age
Hormones
Lack of use
Nerve damage
```
75
Three components to muscle attachment
- Origin, insertion, force
76
Attachment site that does not move
Origin
77
Attachment site that moves
Insertion
78
Tension
Force
79
Fascicle arrangement varies based on _____
Position of muscles
80
Fascicles parallel to long axis
| - Unidirectional force
Parallel muscles
81
Example of parallel muscles
Biceps brachii
82
Fan shaped muscles
Convergent muscles
83
Characteristics of convergent muscles
- Multidirectional force
- Versatility
- Generates least amount of force
84
Example of convergent muscle
Pectorais major
85
Feather shaped muscles
Pennate muscles
86
Characteristics of pennate muscles
- Fascicles oblique to long axis
- Tendon passes through muscle
- Greatest force
87
Example of pennate muscles
Deltoid
88
Characteristics of circular muscles
- Concentric fascicles around opening
| - Contraction decreases lumen diameter
89
Example of circular muscles
Orbicularis oculi
90
Rotation around one axis
Uniaxial
91
Movements produced on a uniaxial axis
- Rotation: atlantoaxial, pivot joints
| - Angular: knee, IP joints
92
Movements occurs along 2 axes
Biaxial
93
Angular motions of biaxial movements
- Flexion/extension
- Abduction/adduction
Ex: ellipsoidal joint, radiocarpal, metacarpal phalange; carpometacarpal (2-5)
94
Movement on all axes
Multiaxial
95
Angular motions of multiaxial
- Same as biaxial
- Rotation
- Circumduction
- Ex: ball and socket
96
Main muscle causing directional force
Agonist
97
This can be any muscle of interest
Agonist
98
Muscle that contracts to oppose agonist
Antagonist
99
Examples of antagonist pairs
- Bicep brachii
| - Tricep brachii
100
Muscles that assists/modifies movement
Synergist
101
Example of synergists
- Brachialis
| - Pronator teres
102
Muscles that stabilizes elements associated with agonist
Fixator
103
Example of fixator muscles
Deltoid stabilizes glenohumeral joint
104
Lever systems modify what?
Movements
105
Levers can change what?
- Magnitude of force
- Speed
- Direction
- Distance of limb movement
106
Components of a lever system (with meanings)
- Lever (L) = skeletal element
- Effort (E) = applied force (AF)
- Fulcrum (F) = joint
- Resistance (R) = body part or object moved
107
Explain the two characteristics of first class levers
- Teeter-totter/ See-saw
| - R opposite of E with central F
108
Example of first class levels
```
E = neckextensors
F = alanto-occipital joint
R = skull
```
109
Two components to second class levers
- Wheel barrow
| - E opposite of F to move R
110
Example of second class lever
Plantar extension
E = calf
F = MP joint
R = weight of body
111
Characteristics of third class levers
- Shovel, broom
| - E in between F and R
112
Example of third class levers
Elbow flexion
E = biceps brachii
F = elbow joint
R = weight distal to joint
113
Seven characteristics of skeletal muscle fibers
- Fast acting; high energy requirements
- Anaerobic
- Large diameter
- Densely packed myofibrils
- Large glycogen reserves
- Few mitochondria
- Rapid, powerful brief contractions
114
Characteristics of slow muscle fibers
- More myoglobin; slower sustained contraction
- Aerobic
- Smaller diameter
- Longer to contract
- Contract for longer time
115
Characteristics of intermediate fibers
- Attributes of both
- Similar to fast fibers
- Greater resistance to fatigue
- Exercise (or lack of) can change one muscle type to another
116
Seven characteristics of smooth muscle
- Attached to hair follicles in skin
- In walls of hollow organs and blood vessels
- Nonstriated
- Involuntary control
- Contractions are slow and sustained
- Spindle shaped
- Very elastic
117
These muscles contract slowly and are resistant to fatigue
Smooth muscles
118
Smooth muscles are stimulated by what?
- Nervous system
- Hormones
- Ions
- Stretching
119
Explain why smooth muscles is a single unit
- Many gap junctions
- Sheets of spindle-shaped cells
- Contract together (syncytial contraction )
120
Example of where single unit smooth muscle is
- BV's
- Digestive tract
- Respiratory tract
- Urinary tract
121
Example of multi-unit smooth muscles
- Walls of large BV's
- Uterus
- Iris of eye
122
Why can smooth muscles be multi-unit?
- No or few gap junctions
- Separate fibers; contract independently
- Only contract when stimulated by motor nerve
123
Cardiac muscle characteristics
- Striated in appearance
- Involuntary control
- Autorhythmic
- Network of fibers with intercalated disks at ends
- Found only in heart
