Quiz 3 Study Guide
Muscular Strength and Endurance
1. Explain the difference between muscular strength and muscular endurance.
Muscular Strength: The force that a muscle or muscle group can exert against a resistance in one maximal effort.
Muscular Endurance: The ability of a muscle or muscle group to perform repeated contraction against a submaximal load.
2. What are some of the functions of skeletal muscle?
– Force production for locomotion and breathing
– Force production for postural support
– Heat production during cold stress
3. What muscles are extensors? What muscle are flexors? Give an example for each.
Flexors: Decrease joint angles
Extensors: Increase joint angles
4. What are myofibrils, and myofilaments?
Myofibrils: Smaller unit of muscle fiber/ bundles of very fine fibers that almost fill the sarcoplasm of a muscle cell.
Myofilaments: Myofilaments are bundled together to make Myofibrils. Myofilaments include Actin (thin filaments) and Myosin (thicker filaments).
5. What is a fasciculus?
Bundle of muscle fibers. Each muscle consists of individual muscle cells, or muscle fibers, they are bundled together and are called fasciculus.
6. What is a sarcomere?
Long, fibrous proteins as filaments that slide past each other when a muscle contracts or relaxes. At rest, thin (Actin) and thick (Myosin) filaments do not overlap
completely. During contraction, thin and thick filaments overlap.
7. What is a motor end plate
Pocket formed around motor neuron by sarcolemma
8. What is acetylcholine, and what is its function?
Acetylcholine is an organic chemical that functions as a neurotransmitter—a chemical messenger released by nerve cells to send signals to other cells.
Acetylcholine is released from the motor neuron and causes an end-plate potential (EPP) (AKA depolarization of muscle fiber)
9. What is the function of Ca++ in muscular contraction?
Calcium initiates muscle contraction by binding to troponin which causes tropomyosin to unmask binding site on actin for myosin filament & forn cross bridges. In
absence of calcium cross bridge will be broken and muscle will again gain relaxed state.
10. What is the function of ATP and myosin ATPase?
– ATP is required for muscle contraction as release of energy from ATP hydrolysis provides energy for power stroke.
– Myosin ATPase breaks down ATP as fiber contracts.
11. What is a motor unit? Explain muscle learning.
A motor unit is made up of a nerve connected to number of muscle fibers e.g., picking up a small weight fewer motor units are recruited in comparison to picking
up a larger weight. Training with weights improve the body’s ability to recruit more motor units (a phenomenon called muscle learning).
12. What is an action potential? What is the resting membrane potential of a muscle? What causes the Ca++ be released from sarcoplasmic reticulum?
Action potential: the all-or-none electrical event in the neuron or muscle cell in which the polarity of the cell membrane is rapidly reversed and then reestablished
Resting membrane potential: the voltage difference measured across a membrane that is related to the concentration of ions on each side of the membrane and
the permeability of the membrane to those ions, releases neurotransmitters if there is enough action potential into the neuron cleft and this will then mind to the cell
membrane of the muscle fiber and causes the calcium to release
13. What is hypertrophy? How is it different from hyperplasia?
Hypertrophy is caused by increase in contractile proteins via muscle enlargement whereas hyperplasia is an increase in the number of muscle cells (fibers)
14. What are some of the strength training adaptations?
– Weight training causes increase in size of muscle fiber, which is called hypertrophy
– Hyperplasia: Increase in muscle cell numbers
– Approx 20% increase in phosphagen stores
– Approx 60% increase in muscle glycogen stores
15. What percent of 1RM an individual needs to lift to increase his or her strength.
– Minimum intensity for muscular overload occurs between 60%-70% of 1RM.