WK5-Skeletal Muscle Flashcards
Describe the sliding filament theory.
The sliding filament theory states that actin and myosin form a crossbridge and slide past one another which signifies a muscular contraction.
Where does the energy needed for muscle contraction come from and how does the muscle utilize it ?
energy for muscle contraction comes from the breakdown of ATP by myosin ATPase that is located on the head of myosin filaments
What are the 3 sources of ATP production during muscle contraction ?
ATP-PCr, glycolysis, and oxidative phosphorylation
What are the four domains of exercise intensity ?
Moderate, Heavy, Very Heavy, Severe
What are the factors that contribute to exercise fatigue at different intensities ?
there are two prevailing theories, peripheral fatigue and CNS fatigue. in CNS fatigue the brain receives signals to cease exercise even thought the body may not be at its limit. During high-intensity exercise (i.e., heavy, very heavy, or severe exercise) of short duration (i.e., 1-10 minutes), the causes of muscle fatigue are multifactorial, ranging from decreased Ca2+ release from the sarcoplasmic reticulum to increases in the accumulation of metabolites that inhibit myofilament sensitivity to Ca2+
What are the causes and conclusions of exercise and muscle cramps ?
The two leading theories attribute the involuntary spasmodic episodes to dehydration and reduced electrolytes as well as increased excitability of motor neurons in the CNS. However the most likely conclusion is that cramps are caused by the central nervous system due to hyper excitation of motor neurons in the specific muscle tissue due to abnormal firing of muscle spindles and GTO. Passive stretch typically resolves muscle cramps.
What are the causes and conclusions of exercise and muscle cramps ?
The two leading theories attribute the involuntary spasmodic episodes to dehydration and reduced electrolytes as well as increased excitability of motor neurons in the CNS. However the most likely conclusion is that cramps are caused by the central nervous system due to hyper excitation of motor neurons in the specific muscle tissue due to abnormal firing of muscle spindles and GTO. Passive stretch typically resolves muscle cramps.
What are the three different types of muscle fibers and how do they differ ?
Type I, Type IIa, Type IIx
each differs from the next in their size and ability to produce a more forceful contraction. The ‘higher’ the muscle fiber type the faster the fiber can contract.
What are the differences in muscle fiber types among athletes who practice distance running, track sprinters, and nonathletes ?
Distance runners have on average a 70-80%:20-30% composition of slow to fast fibers
Track Sprinters: 25-30% : 70-75%
Non-athletes: about a 50-50% split
Classify exercise and muscle action types ( i.e. dynamic vs static )
Dynamic: concentric ( muscle shortening) and eccentric ( muscle lengthening )
Static: Isometric ( no change in muscle length )
Define the following: Length-tension relationships, summation, tetanus, post- activation potential
length-tension relationships: each muscle has an optimal length that will produce maximal force for a contraction
Summation: an addition of successive muscle twitches
Tetanus: a sustained contraction where individual twitches become one
post-activation potential: the increase in muscle force production that occurs following a bout of non-fatiguing, submaximal muscle contractions.
What is the correlation between force- velocity/ power as it pertains to muscles?
force, velocity, and power in muscles are increased in muscles with higher percentages of fast twitch muscle fibers.
How does aging and disease impact muscle function ?
sarcopenia, diabetes can lead to age related loss of skeletal muscle mass but can be slowed with training, cancer patients also suffer from a reduction in muscle mass called cachexia which can also be helped with training and nutritional intervention. Muscular dystrophy is a group of hereditary diseases that weakens skeletal muscles characterized by a defect in muscle proteins.
