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In skeletal muscle, does each cell have its own nervous connection, or does a single nerve ending supply a muscle?
Why is the axon terminal so proximal to the T-tubule?
Why is the postsynaptic membrane highly folded?
Microscopically, which is the brightest area in a sarcomere?
Actin filaments are attached to Z-lines and myosin filaments are attached to M-lines - how are they attached?
What are the myosin binding sites hidden by?
Titin attaches myosin filaments to the Z lines of the sarcomere. How far throughout the muscle do they extend?
How many strands of myosin intertwine to form a single filament?
Is crossbridge cycling (myosin head binding to site on actin filament, changing conformation, detaching and re-attaching) a continual process?
How does the arrival of the action potential at the neuromuscular junction lead to release of calcium from the sarcoplasmic reticulum?
What prevents too much calcium being released from the sarcoplasmic reticulum?
List 3 functions of ATP in skeletal muscle contraction.
ATP in the muscle is in limited supply, but is good for providing the initial energy. How long can it fuel maximum exertion for?
Creatinine phosphate is a high energy phosphate group, and can therefore provide energy to maintain maximal muscle exertion for longer than the muscle ATP stores. How long can it provide energy for contraction for?
Anaerobic glycolysis eventually results in fatigue of muscle as energy supplies are depleted. What energy does it use? How long can it support maximal muscle exertion for?
The best energy source of all for sustained muscle activity is oxidative phosphorylation. It takes the longest to become fully active, but if the effort being exerted is submaximal, how long can it support exertion for?
What is the initial trigger for the use of creatinine phosphate in muscle activity/exertion? What does it produce?
Where does the body obtain creatinine?
List the following energy sources in order of increasing ability to support muscle activity for long periods of time: glycolysis, muscle ATP stores, oxidative phosphorylation, and creatinine phosphate.
What supplies most of the ATP when exercising at a low to moderate rate?
Does lactate cause pain in muscles, allow glycolysis to continue, or both, or neither?
Which carriers transport the electrons generated in the Krebs cycle to the electron transport chain?
Which enzyme converts pyruvate to lactate?
Under anaerobic conditions, which enzyme recycles NAD+ from NADH + H+?
Why is the formation of lactate necessary in anaerobic exercise?
What is the Cori cycle?
At lower intensity exercise, what is the main energy source used by muscles?
At higher intensity exercise, what is the main energy source used by muscles?
Which potential energy substrate is only ever a minor contributor to energy production in exercise?
Energy substrates vary differently with regard to exercise duration than with regard to exercise intensity. As exercise intensity increases, there is greater reliance on muscle glycogen. As exercise duration increases, what energy substrate is relied upon to a greater extent?
Do males or females rely more heavily on protein towards the end of an endurance race?
What is the 'crossover concept'?
What is the limitation in fat being used as a main energy source over glycogen (which can lead to exhaustion)?
What does a motor unit consist of?
Within a motor unit, do muscle fibre compositions tend to be homogeneous or heterogeneous?
What is true of the force and fatigue of fast twitch glycolytic muscle fibres?
What is true of the force and fatigue of fast twitch oxidative muscle fibres?
What is true of the force and fatigue of slow twitch oxidative muscle fibres?
The three main types of muscle fibre are defined by what?
Which sport requires the most slow twitch muscle fibres? And which requires the least?
What is the myoglobin content in slow twitch oxidative, fast twitch oxidative, and fast twitch glycolytic muscle fibres?
What is the capillary density (high or low) in slow twitch oxidative, fast twitch oxidative, and fast twitch glycolytic muscle fibres?
What is the mitochondrial density (high or low) in slow twitch oxidative, fast twitch oxidative, and fast twitch glycolytic muscle fibres?
What is the myosin ATPase activity (high, intermediate, or low) in slow twitch oxidative, fast twitch oxidative, and fast twitch glycolytic muscle fibres?
List some possible reasons for the quick generation of fatigue in fast twitch glycolytic muscles.
What is a muscle twitch?
The length of a muscle twitch varies between muscle fibre types. What is the range of variation?
There is a type of muscle contraction activity that looks similar to a muscle twitch with regard to duration. What is this?
What is the latent period after the stimulus is detected but before the contraction is started?
What initiates the relaxation phase of the muscle twitch?
What are the types of muscle twitch (isotonic or isometric) dependent on?
What would the plateau of an isotonic muscle twitch represent?
Which two factors does the force that a muscle is able to generate depend on?
The force in the individual muscle fibres (which contributes to the overall force that a muscle can generate) is dependent on the number of active crossbridges. What is this influenced by?
Isometric contractions are only reproducible, all-or-nothing events if there is low frequency stimulation of that muscle cell. In high frequency stimulation, there is high tension developed. What is treppe and how does it develop?
The greater the fibre diameter, the greater force it can generate - why? Along these lines, which is the biggest type of muscle fibre?
What is the length-tension relationship of a muscle fibre?
How does the nervous system exert control over the amount of force generated by a muscle?
Structurally, how can muscle fibres differ?
True or false: within any given motor unit, fibres tend to be a similar size.
True or false: motor units with mainly larger fibres have more fibres.
Given that motor units tend to contain fibres of similar sizes, and if a motor unit contains large fibres it will contain more fibres, how do you think 'the size principle' with regard to recruiting motor units works?
What is asynchronous activation?
True or false: in light intensity activity there is similar recruitment of different fibre types, with no one type being recruited more than another?
In heavy intensity exercise, when a large amount of force needs to be generated, which muscle fibre type is predominately recruited?
Here is a summary of the components contributing to the generation of force in a muscle.
As well as controlling the force generated by a muscle, the body can control how rapidly this force is generated. What is the relationship between force required and latency?
Which would have a shorter latency of force generation: isotonic or isometric contraction?
