Muscle Physiology 1
What are the 3 types of muscle fibres, name the whole name and thei short for representation like (Type__)
Slow Twitch - Type 1
Fast Oxidative Glycolytic - Type IIA
Fast Glycolytic - Type IIX
What are satellite cells?
Undifferentiated cells
Play an important role in muscle growth and repair
Training (i.e resistance TR) activates them initiating a divide
Why do we not recruit 100% of our muscle fibers?
Because it will result in damage to muscles and tendons leading the muscles separating from the bone
What is muscle fatugue?
a reduction in muscle power output that results from decreased muscle force generation and shortening velocity
What are the other metabolites involved in peripheral fatigue?
Potassium
High Na+/K+ pUMP
Genetics
Hormone Concentrations
Exercise Habits
How are skeletal muscle fibres typed?
Muscle Biopsy - Small piece of muscle is removed
Staining for type of myosin ATPase isoform
- immunohistochemical staining
- gel electrophoresis
What is the length tension relationship - HINT 3 factors persay
Less than optimal length
Fewer cross-bridge interactions = reduced tension development
Optimal length
Max cross-bridge interaction= maximal tension development
Greater than optimal length
No cross bridge interaction = no tension
What are some causes of muscle fatigue? Hint they all have model in them
CV System Model
Energy Supply Model
Neuromuscular Model
Thermoregulatory Model
Biomechanical Model
Psychological Model
Central Governor Model
Answer the following questions.
What muscle fibers would a marathon runner have mostly? What muscle fibers would a sprinter have? What split of muscle fibers would an average population have
1. Slow
2. Fast
3.50/50
What is a force velocity relationship and power velocity relationship?
FVR
Fast fibers function at greater velocities than slow fibers and they produce more force than slow-twitch fibers at a given velocity
PVR
Power for fast twitch fibers is higher at each velocity
Power drops off significantly at 300 degrees/second in slow twitch fibers
Power is force and velocity together
Name the characteristics of motor units
Fast twitch or slow twitch
High force or moderate force or low force
Fast fatigue or fatigue resistant
Name the 2 types of muscle fatigue?
Central and Peripheral
There are 3 factors that contribute to BioChemical Properties, what are they and what do they do?
Oxidative capacity
Type of myosin ATPase isoform
Abundance of contractile protein in muscle fibre
What is the pathways for the Neuromuscular Junction NMJ
Action potential comes from nervous system
No physical contact with muscle
AP stimulates release of ACh
ACh travels across the cleft to open NA+ channels
Generates an end-plate potential that is enough to continue AP
AP travel along muscle fiber membrane down T-tubules
What is the sliding filament theory and what were to happen if we performed an isometric contraction?
Isometric= between
No movement
1. No sliding
2. No advantages of ECC
3. No disadvantages of CON
What are the 3 things that contribute to fatigue?
Phosphocreatine depletion (wingate)
Lack of ATP and buildup up of ADP, affects peripheral fatigue
High glycolytic fatigue, that may contribute to central fatigue
Slow down the function of enzymes it slows down the rate of ATP
What are the 4 Contractile Property factors? Name at least one factor for each of as much info as possible :)
1. Maximal force production
2. Speed of contraction (Vmax) (max velocity)
3. Maximal power output
4. Muscle fibre efficiency
What are the 4 steps to force regulation?
Types and number of motor units recruited
Initial muscle Length
Nature of the Neural Stimulation of Motor Units
Contractile History of the muscle
What happens to both concentric and eccentric movements during exercise, and which are the weakest and strongest?
Concentric = weakest
ATP required to shorten
1. Taking up series elastic component
2. Cross-bridge braking effect
3. Sliding filament effect
Actin slides in same direction as power stroke
Must overcome load
Eccentric = strongest
1. Braking effect that hindered concentric helps eccentric
2. Passive resistance to stretch
Crossbridges stretch while bound to actin
This resistive force is added to cross bridges
You are resisting the load