The functions of skeletal muscles are force production for? (3)
and __________ production during _________ stress
Force production for locomotion, breathing, postural support
Heat production during cold stress
flexors [Increase/Decrease] joint angle
decrease
extensors [Increase/Decrease] joint angles
increase
Name the 3 layers of connective tissue associated with muscle?
1. Epimysium
2. Perimysium
3. Endomysium
______ surrounds entire muscle
epimysium
______ surrounds bundles of muscle fibers (fascicles)
perimysium
________ surrounds individual muscle fibers
endomysium
fascicles are?
bundles of muscle fibers
Connective Tissue ________ and ____________ components of skeletal muscle
Stabilizes; Supports
PICTURE
3 layers of connective tissue associated with muscle
PICTURE
The _____ is the cell membrane surrounding the muscle fiber.
sarcolemma
The basement membrane is just below the?
endomysium
____________ cells play role in muscle growth and repair?
satellite
a group of contractile proteins or Filaments are known as?
Myofibrils
Thin filaments within myofibrils are called?
Actin
Thick filaments within myofibrils are called?
Myosin
sarcomere includes?
Z line, M line, H zone, A band, I band
The basic skeletal muscle contractile unit is?
The Sarcomere
A sarcomere is the distance between two ________ lines
Z lines
M line of sarcomere holds _________ in __________
Myosin in Place ( M Line is also the Mid Line of the Sarcomere)
The ______ Zone contains Myosin
H Zone ( M Line is in H Zone)
The _______ Band is the area where Actin and Myosin overlap
A Band
The ______ Band contain Actin within the Sarcomere?
I Band
The sarcoplasmic reticulum stores and releases ___________
calcium
calcium is stored in SR within the
terminal cisternae
The ________ ________ extend from the sarcolemma to sarcoplasmic reticulum
transverse tubules
neuromuscular junction or motor end plate is the junction between________ ________ and ________ _________?
Motor neuron and muscle fiber
what is a motor unit?
motor neuron and all fibers it innervates
The neuromuscular cleft is a short gap between ___________ and _________?
neuron and muscle fiber
what neurotransmitter is released from the motor neuron
acetylcholine
acetylcholine once released causes an ______ ______ potential or ___________ of muscle fiber?
end plate potential (EPP) or depolarization
the depolarization travels through?
t-tubules
if there is no depolarization the muscle will be?
weak and flaccid
the sliding filament model occurs when the muscle shortening is occurring due to the movement of?
actin over myosin
when actin is moving over myosin there is a formation of?
cross bridges (power stroke)
during the sliding filament model there is a reduction in the distance between?
z lines of the sarcomere
_____is required for muscle contraction
ATP
myosin ATPase breaks down ______ as fibers contract
ATP (ATP --> ADP + Pi)
sources of ATP=(3)
phosphocreatine
glycolysis
oxidative phosphorylation
The process of contraction from motor neuron through sarcomere shortening is called?
excitation-contraction coupling
When an Electrical impulse is generated at a neuromuscular junction, it is called?
Excitation
Action potential travels down the transverse tubules and causes release of _____ from SR
calcium
Calcium binds to _____ and causes position change in ______ which exposes active sites on actin
troponin; tropomyosin
Strong binding state is formed between actin and myosin and a ____ occurs
contraction
muscle relaxation occurs when the motor neuron stops exciting the muscle fiber and ______ is pumped backed into?
calcium; sarcoplasmic reticulum
removal of calcium from the cytosol causes a position change in ______ which blocks the myosin cross bridge binding site on the actin molecule resulting in muscle relaxation
tropomyosin
what are the properties of contractile proteins?
maximal force production
speed of contraction
maximal power output
muscle fiber efficiency
muscle force production is the force per unit
cross sectional area
speed of contraction (V max)=
myosin ATPase activity
maximal power output-high force, fast fibers have high
power output
muscle fiber efficiency- lower amount of ATP used to?
generate force
How are skeletal muscle fibers typed?
muscle biopsy
staining for type of myosin ATPase isoform
Immunohistochemical staining
gel electrophoresis
muscle biopsy is when a small piece of muscle is removed and may not be representative of entire body. T/F
true
immunohistochemical staining is when selective antibody binds to a unique
myosin protein (fiber types differentiated by color difference)
gel electrophoresis identify myosin isoforms specific to different fiber types. T/F
true
lack of dystrophin protein causes?
membrane destabilization and activation of multiple pathophysiological processes (many converge on alterations in intracellular calcium handling)
type 1 fibers=(2)
slow twitch fibers
slow oxidative fibers
type 2x fibers are ____ in number of mitochondria
low
type 2a fibers=(2)
intermediate fibers
fast oxidative glycolytic fibers
type 2x fibers are _____ in resistance to fatigue
low
type 2x fibers=(2)
fast twitch fibers
fast glycolytic fibers
type 2x fibers predominant energy system used?
anaerobic
type 2x fibers have the highest?
ATPase activity and Vmax(speed of shortening)
type 2x fibers have ____ efficiency
low
type 2x fibers have a high?
specific tension
type 2a fibers have high/moderate?
number of mitochondria and resistance to fatigue
type 2a fibers use predominantly what energy system
combination of anaerobic and aerobic
type 2a fibers have a high?
ATPase activity
Vmax (speed of shortening)
specific tension
type 2a fibers have a moderate?
efficiency
type 1 fibers have a high?
number of mitochondria
resistance to fatigue
efficiency
type 1a fibers use what energy system
aerobic
type 1a fibers have low?
ATPase activity
Vmax (speed of shortening)
type 1a fibers have moderate specific tension. T/F
true
non athletes have approx. ____ slow fibers and ____ fast fibers
50%; 50%
power athletes such as sprinters have higher percentage of
fast fibers
endurance athletes such as distance runner have a higher percentage of?
slow fibers
during an isometric contraction the muscle exerts force without
changing the length
what is an example of an isometric muscle contraction
pulling against an immovable object
postural muscles use isometric contractions. T/F
true
what are the 2 dynamic or isotonic type of contractions
concentric and eccentric
concentric contraction=
muscle shortens during force production
eccentric contraction=
muscle produces force but length increases
eccentric contraction are associated with muscle fiber?
injury and soreness
muscle twitch is a contraction as the result of a?
single stimulus
There is a latent period after the stimulus lasting ___ ms
5
When a contraction occurs tension is developed for 40 ms. T/F
true
It takes 50 ms for relaxation to occur. T/F
true
speed of shortening is greater in ____ fibers
fast
Speed of shortening is greater in fast fibers because?
SR releases calcium at a faster rate and there is higher ATPase activity
more motor units=
greater force
fast motor unit=
greater force
muscle must be at ideal length for?
force generation and increased cross bridge formation
active insufficiency is when the muscle is unable to generate force needed due to?
the length of the muscle (either to short or to long to generate force of contraction)
passive insufficiency is related to?
ROM (ex: 2 joint muscles)
frequency of stimulation
simple twitch, summation, tetanus
sarcopenia=
loss of muscle mass
10% of muscle mass lost between ages 25-50. T/F
true
additional 40% muscle mass lost between age 50-80. T/F
true
With aging there is a loss in fast fibers and gain in?
slow fibers
_____ training can delay age related muscle loss
resistance
what is associated with progressive loss of muscle mass?
diabetes
aerobic and resistance training are protective factors of developing diabetes and age related muscle loss. T/F
true
50% of cancer patient suffer from cachexia which is?
rapid loss of muscle mass
cachexia results in _____ and accounts for 20% of deaths in cancer patients
weakness
What can counteract cachexia?
regular exercise and nutrition therapy
muscular dystrophy are hereditary defects in?
muscle protein
muscular dystrophy results in loss of?
muscle fibers and weakness
Duchene Muscular Dystrophy (DMD) is most common in?
childhood (progression varies based on specific disease type)
at any absolute force the speed of movement is greater in muscle with higher percent of?
fast twitch fibers
the maximum velocity of shortening is greatest at?
the lowest force (true for both slow and fast fibers)
at any give velocity of movement, the power generated is greater in a muscle with a higher percent of?
fast twitch fibers
The peak power increases with velocity up to movement speed of 200-300 degrees/second and power will _____ beyond this velocity because force ____ with increasing movement speed
decreases; decreases