Chapter 1 & 11 Flashcards
The Anatomy of skeletal muscle consist of what 2 things?
Muscle fibers
Myofibrils
What are the 3 types of muscle tissue?
Skeletal
Smooth
Cardiac
Of the 3 types of muscle tissue, which is voluntary?
Skeletal
What does the skeletal muscle connect to?
Skeleton
Where is smooth muscle found?
Hollow organs
Where is cardiac muscle found?
Heart
An entire muscle is surrounded by __________.
Epimysium
An entire muscle consists of many _______ (fascicles or fasciculi)
Bundles
The fascicle is surrounded by _______.
Perimysium
The fascicle consist of individual _____ cells.
Muscle
Each muscle fiber is surrounded by _________.
Endomysium
Muscle fivers consists of myofibrils divided into _________.
Sacromeres
Plasmalemma (cell membrane) fuses with _____.
Tendon
What are the 3 jobs of plasmalemma? (CapMpTn)
- conducts action potential
- maintains pH
- Transports nutrients
What is the cytoplasm of the muscle cell?
Sarcoplasm
What are 2 unique features of sarcoplasm? (GsM)
Glycogen storage & myoglobin
_________ are extensions of plasmalemma.
Transverse tubules
What carries action potential deep into muscle fiber?
T-Tubules
Where is Calcium stored in muscle fibers?
Sarcoplasmic reticulum
What is the sequence of myofibril creation?
Muscle —> fascicle —> muscle fiber —> myofibril
What is the amount of myofibrils per muscle fiber?
Hundreds to thousands
Sections of myofibrils are known as what?
Sarcomeres
What is the basic contractile element of skeletal muscle?
Sarcomeres
To estimate the full length of a myofibril, how should you measure it?
End to end
What are the distinctive striped appearances located on sarcomeres?
Striations
Describe Sarcomere A-bands.
Dark/blue stripes
Describe Sarcomere I-bands.
light/pink stripes
Describe Sarcomere H-zone.
Middle of A-band
Describe Sarcomere M-line.
middle of H-zone
T/F: A-band has both thick and thin filament
True
T/F: A-bands length is measured using both thick and thin filament.
False; only thick filament
T/F: I-band consists of thin filament.
True
What is common boundary structure of the sarcomere?
Z-disk or Z-line
T/F: H-zone consists of thick filament.
True
What are 2 important proteins of the sarcomere?
Actin & Myosin
Thin filaments are composed of what 3 proteins?
Actin
Tropomyosin
Troponin
_______: contains myosin-binding site.
Actin
What protein covers the active site at rest?
Tropomyosin
What protein is anchored to actin and moves Tropomyosin?
Troponin
Myosin is two intertwined ________ with globular heads.
Filaments
T/F: Globular heads can protrude 360 degrees from thick filament axis.
True
T/F: Globular heads will not interact with actin filaments for contraction.
False; they will interact
T/F: Myosin uses Titin as a stabilizer.
True
What myofilament acts like a spring?
Titin
T/F: Titin extends from Z-disk to M-band.
True
What are the 2 main jobs of Titin?
Stabilizes sarcomeres and centers myosin
Prevents overstretching
Muscle fiber contraction starts with ________.
nervous system
Which type of motor neurons innervate muscle fibers?
Alpha
T/F: More operating motor units = more contractile force
True
Fibers contract through a sequence of events known as what?
Excitation-contraction coupling
What are the 6 sequences of excitation-contraction coupling? (AAAATC)
- Action potential (AP) starts in brain
- AP arrives at axon terminal, releases ACh
- ACh crosses synapse, binds to ACh receptors on plasmalemma
- AP travels down plasmalemma, T-Tubules
- Triggers Ca+2 release from sarcoplasmic reticulum (SR)
- Ca+2 enables actin-myosin contraction
T/F: SR sensitive to electrical charge.
True
When AP arrives at SR from T-tubule, is causes mass release of _____ into _____.
Ca+2 ; sarcoplasm
_______ binds to ______ on _____ filament.
Ca+2 ; troponin ; thin
When Ca+2 binds to troponin on thin filament, myosin binds to actin forming a ________ allowing a contraction to occur.
Cross-bridge
The Sliding Filament Theory is a process of _________ contraction.
Actin-myosin
What happens during the relaxed state of sliding filament theory?
- No actin-myosin interaction at binding site
- Myofilaments overlap a little
What happens during the contracted state of the sliding filament theory?
- Myosin head pulls actin toward sarcomere center
- Filaments slide past each other
- Sarcomeres, myofibrils, muscle fiber all shorten
What is power stroke?
Myosin head pulling actin toward sarcomere center.
What happens after power stroke ends?
- Myosin detaches from active site
- Myosin head rotates back to original position
- Myosin attaches to another active site farther down
The sliding filament theory continues until what 1 of 2 things happen?
- Z-disk reaches myosin filaments OR AP stops, Ca+2 gets pumped back into SR.
What is a cross-bridge?
When myosin meets actin
What is the energy unit for muscle contraction?
ATP
ATP binds to _____ head.
Myosin
What is located on the myosin head?
ATPase
T/F: ATP is necessary for muscle contraction.
True
When muscle relaxation occurs, what 2 things end/stop.
- AP ends
- Electrical stimulation of SR stops.
What length does not change during muscle contraction?
A-band
T/F: Muscle relaxation requires ATP.
True
T/F: Muscle biopsy consist of a small (10-100g) piece of muscle removed and is frozen, sliced, examined under microscope.
True
What are the colors designated with a certain type of muscle fiber:
Type 1
Type 2a
Type 2x
Type 1: black
Type 2a: white
Type 2x: gray
Type _______ muscle fiber has a slow form of myosin ATPase
1
Type _____ muscle fiber has a fast form of myosin ATPase.
2
What is the percentages of each muscle fiber type?
Type 1: 50%
Type 2a: 25%
Type 2x: 25%
Which type of muscle fiber has high aerobic endurance?
Type 1
Which muscle fiber type is being described:
- Efficiently produce ATP from oxidation of fat and carbohydrate
- Can maintain exercise for prolonged periods
- Require oxygen for ATP production
- Recruited most often during low intensity
- aerobic exercise (e.g., marathon running)
- daily activities (walking)
- posture
Type 1
Type II fibers in general are ____ in aerobic endurance and produce ATP through ______ pathways.
Poor ; anaerobic
Type _____ produce more force, faster fatigue than type ____ and are primarily used in short, high intensity endurance events (1,600m run).
IIa ; I
Type ______ are seldomly used for everyday activities and primarily used in short,explosive sprints (100m).
IIx
Which muscle fiber type’s motor unit has a greater neuron size?
Type II
List the muscle fiber types in order of greatest peak power to least peak power.
Type IIx > Type IIa > Type I
T/F: Each person has unique ratios of muscle fiber types.
True
Type I predominates in ______ athletes and Type II predominates in _____ athletes.
Endurance ; power
T/F: The Soleus is type I in everyone.
True
T/F: The lose of type II motor units occurs with aging.
True
T/F: Fiber type is the sole predictor of success.
False
What are the 4 factors of athletic success? (CfMThMs)
- Cardiovascular function
- Motivation
- Training habits
- Muscle size
When a motor unit is recruited, ___ of its fibers are ______.
ALL ; activated
Less force: _____ or ______ motor units (type __)
Fewer ; smaller ; I
More force: ____ or _____ motor units (type __)
More ; larger ; II
What is the recruitment order?
- Smallest (type I) motor units
- Midsized (type IIa) motor units
- Largest (type IIx) motor units
What is the principle that states: “order of recruitment of motor units directly related to size of alpha-motor neuron”.
Principle of orderly recruitment (size principle)
Smaller motor units are ___-threshold.
Low
Progressively higher threshold motor units are recruited based on the increasing demands of the _______.
Activity
Which muscle contraction type requires muscle to produce force and change length ; joint movement produced?
Dynamic
What are the two subtypes of dynamic muscle contraction?
Concentric & Eccentric
T/F: Concentric contraction implies that the muscle shortens while producing force.
True
Which contraction requires the muscle to lengthen?
Eccentric
Which muscle contraction is being described:
- Muscle produces force but does not change length
- Joint angle does not change
- Myosin cross-bridges form and recycle, no sliding
Static (isometric)
Amount of force developed depends on what 5 things?
- Number and type of motor units activated
- Size of the muscle
- Frequency of stimulation of each motor unit
- Muscle fiber and sarcomere length
- Speed of contraction
T/F: More force generated when more motor units activated.
True
What is the contractile response to single electrical stimulus?
Twitch
What are consecutive stimuli for greater force?
Summation
What is continued stimulation resulting in peak force?
Tetanus
What it’s the process of varying levels within the frequency of stimulation?
Rate coding
T/F: Optimal sarcomere length = optimal overlap of actin/myosin
True
T/F: Too short or too stretched = little or great force develops .
False; little to no force
The ability to develop force also depends on speed of contraction is known as what relationship?
Speed-Force
Concentric: maximal force development _______ at _____ speeds.
Decreases ; higher
Eccentric: maximal force development ______ at _____ speeds.
Increases ; higher
Substantial strength gains via ___________ changes.
Neuromuscular
T/F: Resistance Training is important for overall fitness and health.
True
After ____ to ____ months of resistance training, you can notice 25 to 100% strength gain, learn more effectively to produce force, learn to produce true maximal movement.
3 to 6
Why do young men experience greatest absolute gains versus young women, older men, and children?
Incredible muscle plasticity
