S/F Muscle One Flashcards
what is the end result of muscle force?
bone movement
what is the fundamental unit of a muscle that creates force?
sacromere
what are sacromeres in series called
myofibril
what is a muscle cell called
fiber
what surrounds a fiber
endomysium
what is a group of fibers
fasicles
what surrounds the fasicles
perimysium
what surrounds the entire muscle
epimysium
sliding filament hypothesis states that following electrical stimulation:
1 - myosin heads form rotating cross brides with actin filament
2 - actin is pulled over myosin
__________ created is directly proportional to the number of simultaneously formed cross bridges
active force
(length tension relationship)
what part of the sarcomere is the anchor point for actin and myosin filaments
Z line
what part of the sarcomere is the anchor point for myosin (midpoint)
M-line
what band only contains actin
I-band
what shortens in the sarcomere during contraction
H and I band
what part of the sarcomere contains myosin and only variable levels on actin
A-band
what band only contains myosin and is located within A-band
H band
what band does not change length with a muscle contraction
A band
fusiform or strap muscles are built for
speed
fusiform or strap muscle fibers are _________ with the tendon
parallel
what is an example for fusiform or strap muscles
biceps or sartorius
pennate muscles are built for_______
force
pennate muscle fibers are _______ to the tendon
oblique
example of unipennate muscles
tib post
semimembranosis
example of bipennate muscles
gastroc
vmo
vi
examples of multipennate muscles
deltoid, glute max
what is additive shortening
muscle fibers with more sarcomeres in series shorten more
increased shortening over similar time = increased velocity
why do pennate muscles create more force
because there is not a 1:1 ratio between fiber length shortening and muscle length shortening. there is greater muscle fiber length shortening which adds up to increase the resultant force
max force potential of a muscle is proportional to:
the sum of the PCSA of all its fibers
(physiological cross sectional area)
greater PCSA =
greater force development
PCSA is greater for what muscle architecture
pennate muscle because it has an oblique angle
passive length tension:
at some critical muscle length, increasing stretch results in storage of strain energy available to do work
increased passive stiffness with:
increase length and increased velocity (viscoeleastic)
active length-tension relationship
want there to be an appropriate amount of overlap between sarcomeres in order to produce optimal force
what is the active contractile component of the hill type muscle model
actin myosin cross bridges
what is the passive parallel elastic component of the hill type muscle model
- runs parallel to contractile proteins
- connective tissue at z lines, endomysium, perimysium
what is the passive series elastic component of the hill type muscle model
- joins end to end with contractile proteins
- tendon and titin
after an achilles tendon elongation repair, the typical elongation is 10-15%. what is this effect?
greater length (larger ROM) required to develop equivalent force
passive insufficiency
multi joint muscle stretching will not allow full ROM at each joint crossed
active insifficiency
multi joint muscle under active tension cannot produce force through available ROM at each joint crossed
generally we experience reduced force of the agonist (__________) before resistance of the antagonist (_____________)
active insufficiency
passive insufficiency
T or F: force and power hit peak values under the same conditions
FALSE
concentrically you cannot max both at the same time
- greatest force produced when muscle does not change length
- greatest speed produced under no load
muscle produces greatest force when it:
does not change length
muscle produces greatest speed when it is:
under no load
linear power =
force x velocity
angular power =
torque x angular velocity
muscle force varies with contraction velocity. order from strongest to weakest
eccentric, isometric, concentric
T or F: at a given force, concentric muscle contraction:
- decreases metabolic cost
- decrease CV load
- decreases neural cost
- decreases fatigue
- increases DOMSr
false, eccentric does silly
there is some evidence of potentially greater strength gains with ___________ overload training for the elderly, frail, and athletes alike
eccentric
