Muscle Structures Review

Which of the following statements about skeletal muscle is true:

• Short muscle fibers run at an angle to the longitudinal axis of the muscle.

• Skeletal muscles are usually linked to each other by tendons.

• Skeletal muscles are not capable of rapid contraction and relaxation.

• During muscle contraction, skeletal muscle lengthens.

Which of the following statements about tendons is false:

• Like muscle, tendons also have the ability to shorten or contract.

• Tendons function to move various parts of the skeleton in response to skeletal muscle contraction.

• One end of the tendon is usually linked to bone and the other to a skeletal muscle.

• Tendons are bundles of collagen fibers.

A muscle or group of muscles opposing an action is called the:

• antagonist

• agonist

• synergist

• prime mover

• fixator

A muscle or group of muscles opposing an action is called the:Skeletal muscle is made up of numerous cylinder-shaped cells called:

• muscle fibers

• myofilaments

• myofibrils

• motor units

• myosins

Which of the following statements about sarcomeres is false:

• Each sarcomere is made up of two types of protein myofilaments: actin, the thick filament, and myosin, the thin filament.

• Sarcomeres are organized in series within the muscle fiber.

• Projecting from each myosin filament are myosin bridges, the tiny contractile elements.

• Examining the sarcomere longitudinally we see the striations characteristic of skeletal muscle.

• All Statements are True

The space between the ends of the two sets of thin filaments in each sarcomere is called the:

• H zone

• Z line

• A band

• M line

• I band

The light region within each sarcomere is known as the:

• H zone

• Z line

• A band

• M line

• I band

The _________ heads are responsible for generating cross bridge formations.

• myosin

• troponin

• tropomyosin

• actin

• myofibril

Which of the following statements about the sliding filament theory is false:

• The I band and the A band shrink but the H zone remains unchanged.

• The myosin filaments temporarily attach themselves to the actin filaments.

• Since the sarcomeres are attached to one another in series, the shortening of each sarcomere is additive.

• It is the sliding of the thin actin filaments over the thick myosin filaments that causes muscle shortening.

• All Statements are True

Which of the following statements regarding maximal force production is false:

• Optimal cross bridge formation occurs when muscle is maximally shortened (i.e., at the smallest joint angle).

• For optimal cross bridge formation, sarcomeres need to be an optimal distance apart.

• Maximal force is developed when an optimal number of cross bridges is formed.

• Muscle stretch is a product of the position of the joint.

• The distance between sarcomeres depends on the state of muscle stretch.