Skeletal Muscle Flashcards
Skeletal muscle classification?
striated
voluntary
muscle fiber = syncytium
Anatomy of skeletal muscle? 3 layers of CT?
myofibril –> muscle fiber –> fascicle
endomysium = surrounds one fiber (LCT)
perimysium = surrounds one fascicle (LCT)
epimysium = surrounds groups of fascicle (dIRCT)
Skeletal muscle fiber appearance?
striations = banding pattern
multi-nucleated – at periphery
Components of sarcomere?
myosin (TH) and actin (th)
Z line = anchor actin
A band
H zone (only actin)
M line = anchor myosin
I band (only myosin)
Sarcomere during relaxed and contracted?
Contraction = Z lines closer, shorter I band
- actin slides past myosin
What are the components of the troponin complex?
TnI
TnT
TnC – binds calcium for tropomyosin to fall of myosin binding site
Tropomyosin function?
wraps actin
covers myosin binding sites on actin (removed by Ca2+)
Satellite cells function?
repair muscle damage
- divide and differentiate into muscle cells
What is the contraction cycle?
ATP attaches to myosin (release from actin)
ATP hydrolysis, head in cocked position
Calcium from T-tubules allows myosin bind to actin
ADP release, head bends, actin slides
Sarcoplasmic reticulum function and structure?
stores calcium
- terminal cisternae surrounds T-tubule (invagination of sarcolemma) to form a triad
Calcium release?
gated calcium release channel
voltage sensor protein (sense change)
calsequesterin (bind free calcium in SR)
calcium pump
Motor unit and innervation?
motor unit = motor neuron + fibers innervated
- innervate few – precise
- innervate more – forceful
3 Types of Muscle Fibres? How to change between them?
change based on exercise frequency
- Type 1 = Red Fiber (aerobic- myoglobin, slow twitch)
- Type 2A = Intermediate Fiber (anaerobic + aerobic)
- Type 2B = White Fiber (anaerobic - glycogen,fast twitch)
