Exam 2 Flashcards
Perimysium
Surrounds bundles of muscle fibers
Epimysium
Surrounds entire muscle
Endomysium
Surrounds individual muscle fibers
Sarcolemma
Muscle cell membrane
Myofibrils
-Threadlike strands within muscle fibers that contain the contractile proteins
-Actin (thin filament)
-Myosin (thick filament)
-Sarcomere
>Z-line, M-line, H-zone, A-band & I-band
Type I fibers
- Slow-twitch fibers
- Slow-oxidative fibers
- much more mitochondria
- most efficient bc you complete oxidation
- red in color
Type IIa fibers
- Intermediate fibers
- Fast-oxidative glycolytic fibers
- red in color
Type IIx fibers
- Fast-twitch fibers
- Fast-glycolytic fibers
- produces more force bc of less mitochondria
- white in color
In what order to muscle fiber types change?
Fast to slow
IIx to IIa to I
Satellite cells
-Undifferentiated cells
-Muscle growth and repair
>Can form new fibers
>Hypertrophy
contractile proteins
They fill Myofibrils
3 important factors of Force Regulation in Muscle
1) Types and number of motor units recruited
2) Initial muscle length
3) Nature of the motor units neural stimulation
Simple Twitch, Summation, and Tetanus
That order (least force to most force)
ST-Larger waves on graph
S-Smaller waves on graph but more of them raising in force
T-Long flat horizontal line on graph
Where is calcium stored?
Sarcoplasmic reticulum
How is calcium released and what does it bind with? And what does it do (what’s its function)?
1) Nerve impulse travels down T-tubules and causes release of Ca++ from SR
2) Ca++ binds to troponin and causes position change in tropomyosin, exposing active sites on actin
3) Permits strong binding state between actin and myosin and contraction occurs
Chronological events in muscle contraction
1) without ca++ found to trophin there in a weak binding state (natural stimulation begins, ca++ is released from sarcoplasmic reticulum
2) formation or strong binding state (release of Pi)
3) cross bridge movement begins (release of ADP)
4) cross bridge movement completed
5) ATP binds to cross bridge. Formation of weak binding state
6) neural stimulation either continues or stops
Motor Neuron
Nerve fiber branch from a nerve cell that is connected to each skeletal muscle cell
Motor Unit
Motor neuron and all the muscle fibers it innervates
The maximum velocity of shortening is greatest
at the lowest force OR The greatest speed of movement is generated at the lowest workloads. True or False
True
Atrophy
A decrease in the mass of the muscle.
Ex. Rigor Mortis
Ex. Sarcopenia
3 Types of dynamic contractions
1) Concentric
2) Eccentric
3) Isokinetic
Concentric Contraction
- Force exerted by muscle or muscle group exceeds external resistance or load
- Joint angle decreases
- Muscle shortens
Eccentric Contraction
- Joint angle increases
- Muscle lengthens while contracting
- Serves as a braking mechanism to decelerate body segment movement
Isokinetic Contraction
- Maximal contraction of muscle or muscle group at a constant velocity throughout entire range of motion (ROM)
- Specialized machines control velocity of contraction and adjust external resistance to match the force produced at degree in the ROM
- Resistance is variable, velocity is constant