Week 02 Flashcards
What is composed of muscle fibres?
Fascicle
What is composed of muscle myofibrils?
muscle fibres/cells
What is composed of sarcomeres?
Myofibrils
What is the mysium?
A sheath of connective tissue allowing gliding between layers
Epi means…
above
peri means…
around
Endo means…
internal, within
What is the perimysium?
Sheath that encapsulates groups of muscle fibres into fascicle
What is the endomysium?
Sheath that wraps around single muscle fibres (space for capillaries and nerves
What is the sarcolemma?
is the cell membrane of a muscle cell.
What is the purpose of the sarcolemma? (4)
Propagation of action potential along muscle fiber, transports metabolites, maintains acid balance
Function of transverse tubules (T-tubules)?
Transmit action potential into fiber via sarcoplasmic reticulum
The Sarcoplasmic reticulum releases and uptakes …
calcium to myofibrils
What is the first step of muscle contraction?
Action potential arrives at terminal of neuromuscular junction (NMJ)
Once the AP reaches the neuromuscular junction, _______ is released to the receptors
acetyl choline (ACh)
After acetyl choline is released, _______ occurs
depolarization (change in ion level)
What happens after depolarization in the sarcomere?
AP travels along sarcolemma and down T-tubules
What could be a rate limiter for speed of contraction? (6)
- Stimulation strength and frequency from axon terminal
- Calcium kinetics (release and uptake)
- Affinity of calcium to troponin
- Myosin ATPase
- Ability of Myosin machinery to produce force
- Energy supply and type
Power =
Power = force x velocity
Factors that effect the ability to produce power? (5)
- frequency of stimulation
- fiber types
- number of motor units
- Architectural factors (parallel vs series)
- Fiber length relative to optimal length (length tension relationship)
Henneman size principle is…?
Recruitment increases as cell body size increases - smaller start recruiting first (type II - largest)
3 benefits of longer fascicle length
- Greater work across ROM
- generate higher shortening speed
- Greater power production capacity
Fascicle length can shorten due to
immobilisation and injury.
Series design increases….
Contraction speed
Parallel design increases….
Force production
Pennation angle allows for….
more packing of sarcomeres in parallel (most muscles)
Slow twitches do/don’t build on top of the last twitch?
DO (too slow to recover from last twitch quick enough)
Fast twitches do/don’t build on top of the last twitch?
DONT (recover too quickly)
Muscle fibre type 2a is more aerobic or explosive?
aerobic
Muscle fibre type 2x is more aerobic or explosive?
explosive
Longer fascicle lengths promotes (3)?
- Greater work across ROM
- Generate higher shortening speed
- Greater power production capacity
