Topic 9 - Locomotion Flashcards
What is the organization of skeletal muscles
Tendons connect muscles to the bone
Muscles are a bundle of muscle fibres
Muscle fibres are composed of myofibril with dark A bands and light I bands
Each muscle cell runs the
entire length of a muscle
What is the structure of Myofibrils
consist of alternating thick (myosin) and thin(actin) filaments arranged along the length of the myofibril
What is a sarcomere?
the functional unit of skeletal muscle
What is the sliding filament model?
how do muscles contract
Muscles contract when the myosin filaments pull the opposing actin filaments toward each other
What is the crossbridge cycle and what is ATP’s role?
ATP binds to myosin causing the cross-bridge to release.
As ATP is split into ADP and P, ATP hydrolysis cocks myosin into position
Myosin attaches to actin to form cross-bridge (high energy configuration)
Myosin releases ADP and P causing working stroke - myosin head pivots and bends as it pulls on actin filament
How do muscles generate force flashback?
More force when the number of cross-bridges between actin and myosin in sarcomere increase
More force when number of muscle cells in tissue increase (bc more muscle = more sarcomeres)
More force when length of the muscle tissue increases (bc more sarcomeres)
More force when muscle contracts more slowly (rapid contraction decreases number of cross-bridges)
How does metabolic rate differ for maximum and sustained? (sprinting vs long distance)
what are the limitations on energy production?
Sprint = 10m/s Ultramarathon = 5m/s
Because there are limitations on energy production such as the limited rate of ATP production and delivery of O2 to muscles takes time
What are the two types of muscle fibres and what are they used for
Slow Twitch (Type 1) - longer duration, or constant contractions with less force
Fast Twitch (Type 2) - fast and short bursts
Explain Slow Twitch (1) muscle fibres
Aerobic oxidation respiration
high mitochondria
high myoglobin
high vascularization
low glycogen
LOW POWER, ENDURANCE
dark meat
Explain Fast Twitch (2) Muscle fibres
anaerobic glucolusis
low mitochondria
low myoglobin
low vascularization
high glycogen
HIGH POWER, BURSTS
white meat
What are the physiological limitations on MRmax or MRsus
order of energy sources
- we have pools of stored ATP in our cells that provide instant energy, but they are used up fast
- we have PCr which is a backup pool of ATP
- when PCr and ATP reserves are used up, we have glycolysis to being quickly making ATP for activity
- Eventually oxidative phosphorylation will kick in
in what order are energy methods used
ATP, PCr, Glycolysis(anaerobic, lactic acid), oxi phosph(aerobic), oxi phosph (triglycerides)
When can MR max be equivalent to MR sus?
During long activities
What happens to metabolic rate before, during, and after exercise
at REST, MRmax is at RMR
DURING EXERCISE: MR increases
there is O2 debt - use cellular pools of ATP/PCr and produce lactic acid,
AFTER EXERCISE, MR lowers back down to RMR during revovery metabolism - cellular pools of ATP and PCr are replenished, lactic acid is removed.
How does MRmax scale with mass
ACTIVE MRmax is log curve, facing down
On log scale, positive slope line
MASS SPECIFIC is log curve facing up
On log scale, negative slope line
How does metabolic scope change for endo and ectotherms
it is roughly the same - same slope, endotherm is slightly higher
potential to increase MR from RMR to MRm is similar (scope)
How is locomotion measured from an energy perspective
Mass-specific Metabolic Rate
Cost of Transport
What is mass-specific metabolic rate
energy required to move 1 unit mass of an organism over 1 unit of time
Units: kJ/kgh
What is Cost of transport (CoT)
energy required to move 1 unit mass of an organism over 1 unit distance
Unit: kJ/kgkm
What factors affect locomotion
intertia
momentum
drag
Inertia
tendency of mass to resist a change in motion
momentum
tendency of a moving mass to sustain velocity
How does inertia and momentum change with mass
Increase as mass increases
