Muscular Tissue Flashcards
1
Q
What percentage of body mass is muscle?
A
40-50%
2
Q
What are the three types of muscular tissue
A
Skeletal
Cardiac
Smooth
3
Q
Skeletal Muscle
A
Move bones. Striated with protein bands
4
Q
Cardiac Muscle
A
Striated. For involuntary action
5
Q
Smooth muscle
A
Walls of hollow internal structures. Non striated. Involuntary action
6
Q
4 functions of muscle
A
Produce body movement
Stabalizing body position
Storing and moving substances
Producing heat
7
Q
4 properties of muscle
A
Electrical excitability
Contractility
Extensibility
Elasticity
8
Q
Electrical excitability
A
Produce action potentials
9
Q
Contractility
A
Contract forcefully when stimulated by an action potential
10
Q
Extensibility
A
Stretch without being damaged
11
Q
Elasticity
A
Return to original shape
12
Q
Structure of skeletal muscle
A
Muscle belly connected by tendons to skeleton
13
Q
Tendons
A
Tough, dense regular connective tissue attaching belly to skeleton
14
Q
Aponeuroses
A
Tendons arranged in flat sheets
15
Q
Endomysium
A
Thin wrapping of reticular fibers surrounding muscle fibers
16
Q
Fasicle
A
Bundles of muscle fibers wrapped in a thicker layer of connective tissue
17
Q
Perimysium
A
Dense irregular connective tissue covering fasicle
18
Q
Epimysium
A
Thicker, dense irregular connective tissue covers perimysium and binds fascicles together to form muscle belly
19
Q
Fascia
A
Dense irregular sheets protecting groups of skeletal muscle
20
Q
Neurovascular Bundle
A
Nerves and blood vessels enter muscle near tendon attachment
21
Q
Myoblast
A
Skeletal muscle fiber arises from fusion of myoblasts
22
Q
Sattelite cells
A
Myoblasts remaining in mature skeletal muscle help regenerate damaged tissue
23
Q
Fibrosis
A
Replacement of muscle tissue by fibrous scar tissue
24
Q
Sarcolemma
A
Plasma membrane of muscle fiber
25
Transverse tubule
Thousands of tiny holes in sarcolemma tunnel towards center of transmit action potentials
26
Sarcoplasm
Cytoplasm of muscle fibers release glycogen for production of ATP
27
Myoglobin
Only in muscles. Binds oxygen molecules that diffuse into muscle fibers
28
Myofibrils
Little contractile threads in sarcoplasm
29
Sarcoplasmic Reticulum
System of fluid filled sacs surround each myofibril
30
Terminal Cisterns
Dilated end sacs of sarcoplasmic reticulum butt against either end of a transverse tubule
31
Triad
One transverse tubule and two terminal cisterns on either end
32
What triggers muscle contraction?
When triggered terminal cisterns release Ca into sarcoplasm
33
Filaments
Small protein structures within myofibrils are involved in contractile process
34
Sarcomeres
Basic functional unit of myofibril
35
Z- Discs
Dense protein plates seperate sarcomeres
36
A- Band
Dark middle part of sarcomere extends entire length of thick filaments
37
Zone of overlap
End of A- band where thick and thin filaments lay side by side
38
I- Band
Less dense area containing only thin filaments
| Z- disc passes through centre
39
H- Zone
Centre of each A- Band contains only thick filaments
40
M- Line
Supporting proteins hold thick filaments together at middle of the sarcomere
41
3 kinds of proteins composing myofibrils
Contractile
Regulatory
Structural
42
Contractile proteins
Generate force
43
Regulatory proteins
Switch contractions on and off
44
3 functions of Structural proteins
Keep filaments in alignment
Give myofibril extensability/ elasticity
Link myofibrils to sarcolemma
45
2 contractile proteins
Myosin
| Actin
46
Myosin
Motor protein that composes thick filaments. Looks like 2 twisted gold clubs
47
Motor proteins
Convert ATP's chemical energy into mechanical energy
48
Which way to the myosin tails point?
Toward the M- Line
49
Actin
Composes thin filaments. Twisted into a helix
50
Where do thin filaments extend from?
Z- disc
51
Myosin binding site
Area on actin where myosin head attaches
52
2 regulatory proteins
Tropomyosin
| Troponin
53
4 primary structural proteins
Titin
Myomesin
Nebulin
Dystrophin
54
Titin
Spans half of sarcomere from Z- disc to M- Line and anchors thick filaments
55
Myomesin
Form the M- Line and hold thick filaments in alignment
56
Nebulin
Anchor thin filaments to Z- Disc
57
Dystrophin
Links thin filaments to sarcolemma to reinforce it
58
Sliding Filament Mechanism
Skeletal muscle shortens during contraction as thick and thin filaments slide past one another
59
How does the sarcomere shorten?
Myosin heads walk up thin filaments pulling them towards the M- line
60
Neuromuscular Junction
Synapse between a motor neuron and a skeletal muscle fiber where muscle action potentials arise
61
What happens before the Contraction cycle can begin?
Ca ions released which binds to Troponin
| Troponin moves Tropomyosin away from myosin binding sites on actin
62
What structure releases Ca ions?
Sarcoplasmic reticulum
63
4 stages of Contraction cycle?
ATP hydrolysis
Cross bridge
Power stroke
Detachment of myosin from actin
64
ATP hydrolysis
Myosin head has an ATP binding site and ATPase which breaks it down ADP to reenergize the myosin head
65
Cross Bridge
Myosin head attaches to actin and releases phosphate group
66
Power Stroke
Site on cross bridge where ADP is bound opens. Bridge rotates and releases ADP so sarcomere contracts
67
Synapse
Region of communication between two neurons
68
Synaptic Cleft
Gap between cells that action potential must jump
69
Axon terminal
End of motor neuron
70
What is the neural component of NMJ?
Synaptic end bulbs
71
Synaptic vesicles
Membrane enclosed sacs within each synaptic end bulb
72
What is the neurotransmitter released at NMJ?
Actylcholine (ACh)
73
What is the muscular component of NMJ?
Motor end plate
74
Acetylcholine receptors
Transmembrane proteins bind to ACh
75
4 steps in producing muscle action potential
Release ACh
Activation of ACh receptors
Produce muscle action potential
Breakdown of ACh
76
Muscle tone
Weak, involuntary contractions of motor units
77
What causes muscle tone?
Neurons in brain and spinal cord excite somatic motor neurons
78
Isotonic Contractions
Tension remains constant while muscle length changes. Body movements and moving objects
79
Concentric Isotonic Contraction
Tension is great enough to overcome load. Muscle shortens and pulls at tendon to reduce angle at joint
80
Eccentric Isotonic Contraction
Length of muscle increases during contraction
81
What type of isotonic contraction produces more muscle damage?
Eccentric
82
Isometric Contraction
Tension generated is not great enough to exceed object being moved . Muscle does not change in length.
83
Which type of contraction is important for posture?
Isometric
84
Red muscle fibers
High in myoglobin
85
White muscle fibers
Low in myoglobin
86
What type of skeletal fiber is white?
Fast glycolytic fibers
87
3 types of skeletal muscle fibers
Slow oxidative
Fast oxidative- glycolytic
Fast glycolytic
88
Slow oxidative fibers
Red muscle fibers produce ATP aerobically. Slow contraction but very resistant to fatigue
89
What contributes to how fast muscle fibers contract?
How fast the ATPase in the myosin head hydrolyzes ATP
90
Fast oxidative- glycolytic fibers
Red muscle fibers produce ATP both aerobically and anaerobically. Faster contraction and resistance to fatigue
91
Fast glycolytic fibers
White muscle fibers produce ATP anaerobically. Contract very strongly and quickly but fatigue quickly
92
What fibers does aerobic exercise change?
FG to FOG
93
What percentage of muscle mass is lost between age 30-50?
10%
94
What percentage of muscle mass is lost by age 80?
50%
95
What is muscle tissue replaced with as you age?
Fibrous connective tissue and adipose tissue
96
What fibers increase as you age?
Slow oxidative fibers
97
Authorhythmicity
Natural pacemaker initiates each cardiac and smooth muscle contraction
98
Which muscle type is subject the most amount of stretching
Smooth
99
What are tendons made of
Parallel arrangements of collagen fibers
100
Function of endomysium
Carries small blood vessels that supply muscle fibers with nutrients
101
How do neuromuscular bundles spread through the muscle
Connective tissue channels formed by the perimysium and endomysium as they wrap the muscle cells
102
Motor fibers
Part of neuromuscular bundle that initiates contractile function of muscle cells
103
Sensory fibers
Part of neuromuscular bundle that provides feedback to the nervous system to regulate motor function
104
Somatic Motor Neurons
Neurons that stimulate skeletal muscle fibers to contract
105
Axon
Threadlike extension of a motor neuron travels from muscle cell body to spinal cord
106
When does the muscle fiber lose its ability to undergo cell division
After fusion of the myoblasts
107
What are transverse tubules filled with
Interstitial fluid
108
Where are the Ca ions when the muscle fiber is relaxed
Sarcoplasmic reticulum
109
Where are the Ca ions when the muscle fiber is triggered
Sarcoplasm
110
Ratio of thick and thin filaments
2 thin for every thick filament in regions of overlap
111
Striations
Patterns of overlap consisting of a variety of zones and bands
112
When is mysosin blocked from binding site by tropomyosin
When muscle is relaxed
113
Synaptic end bulbs
Axon terminal divides into a cluster of synaptic end bulbs
114
Where is ACh stored
Inside synaptic vesicles
115
Motor end plate
Region of sarcolemma opposite the synaptic end bulbs
116
Where are the ACh receptors
In the motor end plates
117
Junction Folds
Deep grooves in the motor end plate that provide a large surface area for ACh
118
Motor unit
Somatic motor unit plus all the skeletal muscle fibers it stimulates
119
What is stimulated by the arrival of a nerve impulse at the synaptic end bulb
Channels open and Ca ions enter synaptic end bulbs
120
Strength Trianing
Exercising with progressively higher resistance to strengthen the musculoskeletal system
121
Intercalated discs
Ends of cardiac muscle fibers connect to neighboring fibers by a thickening in sarcolemma
122
What two cell junctions do intercalated discs have
Gap junctions
| Desmosomes
