Module 4: LAST LECTURE!!! Flashcards
What is the muscle length relationship?
- referring to the length of your sarcomere from z-line to z-line
the amount of overlap between your think and thin filaments will dictate how much force you can generate
What is the optimal muscle length?
maximum amount of force your muscle can generate
- all of your myosin heads are able to interact with a actin filament
What happens when we make our sarcomere longer?
- this is where we increase the distance of out z-discs
- the amount of force our muscle will generate will drop due to the less overlapping of the actin and myosin filaments
True or False
Lengthening the muscle will cause a decrease in the amount of force generation
True, because we decrease the amount of potential cross-bridges that can form
What happens when we make our sarcomere shorter?
- decrease the distance form z-line to z-line
- the amount of force our muscle will generate will drop due to the thin filaments “bumping” into one another altering the structural organization of our sarcomeres
= decreases the number of available sites that you can from cross-bridges
True or False
Shortening the muscle will cause a decrease in the amount of force generation due to the overlapping thin firmament, limiting the number of active site available for cross-bridges to form
True
What stops us from getting to an extreme lengthening or an a extreme shortening of the muscle?
our joints
In what case/scenario will your H-zone disappear?
when your muscles are shortened to the point where your actin filaments are bumping into each other
What are the 2 kinds of muscle contractions?
- Isotonic
- Isometric
What is muscle tension?
the force exerted BY a muscle contraction on an object
- aka the amount of force a muscle is producing
What is a muscle load
the force exerted ON a muscle by an object
- aka the object is implementing “x” amount of force on a muscle when we for instance are carrying it
True or False
The muscle tension is the tension in the muscle fibres itself?
true
True or False
The amount of force that the object is placing on muscle fibres is referred to as the muscle load?
True
The balance between muscle tension and muscle load will dictate what?
the kind of muscle contraction that occurs
- whether the muscle shortens or lengthens
If the muscle tension is greater than the load what will happen?
shortening
If the muscle tension is lesser than the load what will happen?
lengthening
What is an isometric contraction?
no change in muscle length
What is a isotonic contraction
where shortening or lengthening occurs in the muscle
- constant load, tension in the muscle
Shortening can be referred to as?
concentric contractions
Lengthening can be refereed to as?
eccentric contraction
iso means?
same
tonic means?
tension
Metric means?
length
What is the force velocity relationship?
how much force a muscle can produce relative to what velocity that muscle is contracting at
*Referring to the shortening phase of the muscle
What would an isometric contraction look like relative to the force velocity relationship graph?
where velocity is = 0
- not change on muscle length
When can we produce the maximum force?
at an isometric contraction
- where the velocity is 0
What is the unloaded shortening velocity? (Vmax)
the fastest velocity that your muscles are able to shorten at
True or False
We will never experience the unloaded shortening velocity unless in a lab?
true
What is power?
force x velocity
What is your peak power of the muscle?
maximum amount / highest energetic contraction we can produce
When can maximum power be produced?
when theres an optimal load and velocity relationship
What are the 3 fibre types in humans?
- Type 1 (I)
- slow twitch - Type 2A (IIA)
- fast twitch - Type 2X (IIX)
- fast twitch
True or False
Your myosin ATPase, will dictate whether we have a slow or fast twitch
True
Fast fatigue refer to?
Type 2X
Fast fatigue resistance refer to?
Type 2A
slow fibres refer to?
Type 1
In what instance can we get changes in our muscle fibre variations?
spinal cord injuries, all your slow twitch fibres turn onto fast twitch fibres
come back too!!!
What are the 2 OVERALL factors changing the whole-muscle tension in the muscle? and other sub-factors?
- Change the number of fibres that are contracting
- # of motor unit recruitment
- # of muscle fibres per motor unit
- # of muscle fibres available to contract- size of muscle fibres (# of muscle fibres within a muscle)
- presence of disease
- extent of recovery from injury
- Change the tension developed by each contracting fibre
- frequency and activation rates- twitch summation
- length of fibre
- length-tension relationship
- Extent of fatigue
- fibre type
- duration of activity
- Thickness of fibre
- twitch summation
What is the number 1 factor that is going to dictate how much force is actually being generated in the muscle?
the size of the muscle fibre
- the more myofibrils in the muscle fibres the more cross-bridges can form overall
is there more slow twitch or fast twitch motor units overall in our muscles?
slow twitch
What kind of energy is used for type 1 muscle fibres?
Slow oxidative
What kind of energy is used for type 2A muscle fibres?
fast oxidative glycolytic and some slow oxidative
What kind of energy is used for type 2X muscle fibres?
fast oxidative glycolytic
What are the structural properties of the muscle fibres?
- diameter
- motor units per muscle
- SR development
What are the diameter, motor units per muscle and SR development of the slow, fast A and fast X twitches?
Slow:
diameter = small
motor units per muscle = more, smaller
SR development = poor
Fast A:
diameter = large
motor units per muscle = fewer, larger
SR development = intermediate
Fast X:
diameter = large
motor units per muscle = fewer, larger
SR development = high
What are the functional properties of the muscle fibre?
- twitch time
- relaxation time
- force production
- fatiguability
- sensitivity to recruitment
What are the twitch time, relaxation time, force production, fatiguability and sensitivity to the recruitment of the slow, fast A and fast X twitches?
Slow:
twitch time = slow
relaxation time = slow
force production = low
fatiguability = fatigue-resistant
sensitivity to recruitment = high
Fast A:
twitch time = fast
relaxation time = intermediate
force production = intermediate
fatiguability = fatigue
sensitivity to recruitment = intermediate
Fast X:
twitch time = fast
relaxation time = fast
force production = high
fatiguability = most fatigable
sensitivity to recruitment = low
What are the metabolic properties of the muscle fibre?
- red colour
- myosin-ATPase activity
What are the red colour and the myosin-ATPase activity of the slow, fast A and fast X twitches?
Slow:
red colour = dark
myosin-ATPase activity = low
Fast A:
red colour = dark
myosin-ATPase activity = intermediate
Fast X:
rec colour = pale
myosin-ATPase activity = high
