Lecture 19 Flashcards
What is MTC stand for
Muscle tendon complex
What can a MTC only do
Pull
Cannot push
Force developed in MTC attempts to do what
Bring the two insertion points closer together
When hopping vertically, the propulsive phase (plantar flexion):
MTC is…
Whole body PE and KE…
Force generated by MTC and displacement are…
MTC is doing…
Concentric or Eccentric action?
Force produced by MTC greater or lesser than External force as it ______
Shortening
Increases
In the same direction
Positive work
Concentric action
Greater, Shortens
When hopping vertically, the braking phase (dorsi flexion):
MTC is…
Whole body PE and KE…
Force generated by MTC and displacement are…
MTC is doing…
Concentric or Eccentric action?
Force produced by MTC greater or lesser than External force as it ______
Lengthening
Decreases
Are in opposite directions
Negative work
Eccentric action
Lesser, Lengthens
MTC concentric action is where:
F MTC is…
Change in displacement is…
F MTC > F external
Change in displacement is in same direction as F MTC
MTC eccentric action is where:
F MTC is…
Change in displacement is…
F MTC < F External
Change in displacement is in opposite direction as F MTC
MTC Isometric action is where:
F MTC is…
Change in displacement is…
F MTC = F External
No displacement = 0
The major contractile unit of a muscle is the…
Sacromere
Contractile proteins are
Actin
Myosin
What does sacromere shortening result from
Relative movement of myosin which pulls actin to the center
What does muscle architecture refer to
How fibers of a muscle are arranged relative to the vector of the force generation
Parallel is in what axis
X axis
Pennate is what…
Diagonal from x axis
What are the factors that influence MTC force producing capacity
Cross sectional area
MTC length
Type of action
Velocity
Fiber type
Recruitment
Time history of activation
Will a bigger muscle (bigger volume) produce more force
Not always
Depends on physiological cross sectional area
The physiological cross sectional area is located
Perpendicular to the fibers
What physiological cross sectional area is larger in
Longitudinal muslce (5cm)
Pennate muscle (5.77cm)
???
Force length relationship:
Ascending phase
Large overlap between actin and myosin heads
Small number of cross bridges that can be formed
When length increases
More cross bridges can be formed
Force length relationship:
Resting legnth, plateau phase
Optimal number of actin myosin interactions
Force length relationship:
Descending phase
Actin and myosin are too far apart
Decrease number of cross bridges that can be formed
