Lecture 6: Introduction to the Muscular System Flashcards
1
Q
What are the 3 types of Muscle?
A
- Skeletal
- Cardiac
- Smooth
2
Q
What are the 4 Basic properties of muscles?
A
- Excitability
- Contractility
- Extensibility
- Elasticity
3
Q
What is Excitability?
A
The ability to respond to stimuli
4
Q
What is Contractibility?
A
Ability to shorten (pull/tension)
5
Q
What is Extensibility?
A
Ability to contract over different lengths
6
Q
What is Elasticity?
A
The ability to regain original length after contraction
7
Q
What are the Major characteristics of Skeletal Muscle?
A
- Somatic structures
- Innervated by spinal nerves and cranial nerves
- Contractile organs that attach directly or indirectly to bones in the longitudal axis
- Their contractions produce motion of the body
8
Q
What is meant by Skeletal muscles are somatic structures?
A
They are under voluntary control
9
Q
Which nerves are Skeletal muscles innervated by?
A
Spinal nerves
Cranial nerves
10
Q
Where do Cranial nerves originate from?
A
The brainstem
11
Q
If a skeletal muscle attaches indirectly to bone what must it connect through?
A
A tendon
12
Q
What kind of connective tissue are tendons?
A
Dense regular connective tissue
13
Q
What are the major functions of Skeletal Muscle?
A
- Produce movement at various joints of the skeleton
- Maintain posture and body position
- Support soft tissues
- Regulate entering and exiting of material
- Maintain body temperature
14
Q
How does the Skeletal muscle support soft tissues?
A
The Abdominal wall and pelvic floor support viscera
15
Q
How does skeletal muscle regulate entering and exiting of material?
A
Sphincters in digestive and urinary systems
16
Q
What does EVERY organ always have?
A
All 4 basic tissues
17
Q
What is one muscle going to be wrapped in?
A
Connective tissue called Epimysium
18
Q
What is Epimysium?
A
The connective tissue that wraps around one muscle
19
Q
What separates the different compartments?
A
Fascia
20
Q
What is the Epimysium continuous with?
A
The Fascia
21
Q
What are skeletal muscles divided into?
A
Muscle Fascicle
22
Q
What is a Fascle?
A
A bundle of Muscle cells
23
Q
What is a Muscle fibre?
A
One nerve cell
24
Q
How many muscle fibres are in each fasicle?
A
Multiple
25
What are Fascicles wrapped in?
Perimysium
26
What is every muscle fibre wrapped in?
Endomysium
27
How do a Nerve, arteries and veins enter the muscle?
Via the Epimysium
28
What is 1 axon associated with?
1 muscle fibre
29
Why do each muscle fibres have a lot of capillaries?
Because muscles need a lot of oxygen
30
Where do Capillaries of Skeletal muscle fibres sit?
In the Endomysium
31
What do Skeletal muscles look like?
* They are very long
* Striated
* They have multiple nuclei that are never in the middle
32
Why do Skeletal muscles only have nuclei in the periphery?
Because they develop from many myoblasts that form one muscle fibre
33
What are Myosatellite cell?
Skeletal fibre stem cells that remain stem cells into adulthood to repair damaged tissue
34
Where are Myosatellite cells found?
In the Endomysium of muscle fibres
35
What is the length of muscle fibres?
They are the entire length of muscles themselves
36
Where do we have all the contrile elements?
In the myofibrils
37
What are myofibrils made of?
Proteins that are thick and thin
38
What are the length of Myofibrils?
Every myofibril is the length of the muscle fibre
39
What is the Plasma membrane of muscle fibres known as?
Sarcolemma
40
What is the Cytoplasm of the muscle fibres known as?
Sarcoplasm
41
What is found within each muscle fibre?
Myofibrils
42
What is each myofibril wrapped in?
Sarcoplasmic reticulum
43
What is stored in the Sarcoplasmic reticulum?
Calcium ions
44
What are Transverse tubules?
Wrapping of a myofibril that conducts electrical impulses for a muscle fibre contraction
45
Where are Mitochondria and Glycogen granules found around the skeletal muscles?
Around myofibrils
46
What are both needed for the energy of contraction of muscle fibres?
Mitochondria and glycogen granules
47
What is the only thing were going to have multiple of the length of the Myofibril?
Sarcomeres (10000 per myofibril)
48
What is the Basic contractile unit of Skeletal muscles?
Sarcomeres
49
What are the boundaries of the Sarcomere?
Z lines
50
What is in the Middle of the sarcomere?
The M line
51
What are on the M line?
Thick filaments of Myosin
52
What go from the Myosin to the Z line?
Titin
53
What does Titin do?
Connect myosin to the Z line
54
What are the Thin myofilaments around Myosin?
Actin
55
What does the H band contain?
Thick filaments only
56
What does the I band contain?
Thin filaments only of Actin and Titin
57
What doed I band look like in microscopy?
They are lighter
58
What does the A-band contain?
Both thick and thin filaments
59
What is in the Zone of overlap?
Both thin and Thick filaments
60
What occurs in the zone of overlap?
Calcium ions are released
61
How are the length of filaments changed?
They never change length they only overlap more or less
62
What is Cross-Bridging?
When Myosin heads bind to Actin
63
What is required for Cross bridging to occur?
* Calcium ions
| * ATP
64
Where does the Myosin push the actin?
Towards to the M line
65
Which band is constant?
The A band - the band of thick filaments only
66
How are the I band and H band affected by muscle contraction?
They reduce in size
67
When does the actin stop moving towards the M line?
When the myosin touches the Z line
68
What are muscle cells innervated by?
Motor Neurons and Sensory neurons
69
What does the one neuron Skeletal muscle penetrate?
The epimysium, then the perimysium and the one axon will end at the endomysium
70
What is the Neuromuscular Junction?
Where the axon of the neuron meets the muscle fibre where it releases ACh
71
How does a neuron stimulate a muscle to contract?
Contact with the sarcoplasmic reticulum changes the membrane potential signaling the sarcoplasmic reticulum to release calcium ions
72
How is a Muscle Contraction Ended?
* ACh is removes
* Sarcoplasmic reticulum recaptures Calcium
* Active sites covered, no cross bridge interactions
73
How many axons per each muscle fibre?
One axon per one muscle fibre
74
How many muscle fibres can a single motor neuron stimulates?
Multiple muscle fibres
75
What is a Motor unit?
All the muscle fibres controlled by a single motor neuron
76
What does the amount of Contraction depend on?
The number of motor units that are stimulated and the frequency that they are stimulated
77
What are small motor units needed for?
Very precise movement like eye muscle
78
What are large motor units required for?
More Power
79
What is a twitch?
When one quick motor unit is stimulated
80
How do muscles avoid Fatigue?
They activate the motor units on a rotating basis to avoid fatigue
81
What is Muscle tone?
Resting Tension in muscles
82
What is Isotonic contraction?
When tension produced is equal or greater than the resistance/load
83
What are the two main types of contraction?
Isotonic contraction
| Isometric contraction
84
What are the two types of Isotonic Contraction?
Concentric and Eccentric
85
What is Concentric contraction?
Shortening of an active muscle
86
What is Eccentric contraction?
Lengthening of an active muscle
87
What is Isometric contraction?
When tension never exceeds the resistance/load and the active muscle does not change length in contraction
88
What are the two types of Skeletal muscles fibres?
Type I (Slow) and Type II (Fast)
89
What are the Characteristics of Slow fibers?
* Red due to numerous mitochondria and myoglobin
* Narrow diameter
* Takes a long time to contract
* Less myofibrils
* Resistant to fatigue but less powerful
* ATP produced by mitochondria through aerobic metabolism
* More extensive network of capillaries
* Associated with leg muscles and posture
90
What are the characteristics of Fast Fibres?
* White because less myoglobin and mitochondria
* Larger diameter, densely packed myofibrils, large glycogen reserve
* Few mitochondria
* Rapid contraction
* ATP generated by anaerobic glycolysis
* Associated with eye and hand muscles
91
What are the 4 types of Muscle Organization?
* Parallel muscles
* Convergent muscles
* Pennate muscles
* Circular muscles
92
What is the most common organization of Muscles?
Parallel muscles
93
What is the shape of Parallel muscles?
Flat or spindle shaped
94
What is the central portion of spindle shaped muscles?
The belly
95
What happens during contraction of Parallel muscles?
The muscle gets shorter and the belly gets wider
96
How do Parallel muscles exert force?
All fascicles pull in the same direction
97
What is the shape of Convergent muscles?
Fan shaped
98
Where do convergent muscle originate and converge?
The originate over a wide are but converge at a common attachment site
99
How can the direction of the pull change in Convergent muscles?
Depending on which fascicles contract
100
Why do Convergent muscles not exert the same amount of force as Parallel muscles?
Because not all the muscles pull in the same direction
101
What is the Shape of Pennate muscles?
Fan shaped
102
What is the benefit of the feather shaped fibers?
The fibers are able to stack more for a more forceful contraction
103
What are the 3 types of Pennate muscles?
* Unipennate
* Bipennate
* Multipennate
104
What is unipennate?
When muscle fibres are on one side of the tendon
105
What is Bipennate?
When muscle fibres are on both sides of the tendon
106
What is Multipennate?
When the tendon branches within the muscle
107
What does contraction of circular muscles allow?
The diameter of the opening to be reduced
108
What are Skeletal muscle named according to?
Structure or shape of the muscle, specific region of the body, attachment sites, relationship to other muscles, action of the muscle
109
Deltoideus
Triangulat
110
Maximus
Large
111
Brevis
Short
112
What is Action?
The type of movement (function of muscle)
113
What is Insertion?
Muscle attachment to moveable bone
114
What is Origin?
Muscle attachment to stationary bone
115
What are the 4 types of primary muscle actions?
* Agonist (Prime mover)
* Synergist
* Antagonist
* Fixators
116
What is Agonist mucle action?
Contraction produces a particular movement
117
What is Synergist muscle action?
Assists prime mover in performing anaction
118
What is Antagonist muscle action?
Opposes the movement
119
What is Fixator muscle action?
Agonist and antagonist muscle contracting at the same time to stabilize a joint
