PE 461- Test 2- Muscle

Which of the following is NOT a characteristic of skeletal muscles?

Intercalated discs

True:

multinucleated, voluntary control, striated

During what speed of movement will a person be able to lift the heaviest weight?

A slow movement

in the figure showing muscle proteins, which protein does the arrow point to?

Myosin

Calcium ions, responsible for turning on muscle contractions, are stored in the

Sarcoplasmic reticulum

During muscle contraction, which protein has the moving structures that pull on the others?

Myosin

Which of these is NOT true about skeletal muscle?

The individual muscle fibers within the skeletal muscle typically extend the entire length of the muscle

True:

Muscle cells are also referred to as muscle fibers, muscle cells require energy for both the action and relaxation phases of contraction

A motor neuron and all of the muscle fibers it innervates are referred to as a motor unit

Please arrange the events leading to a muscle contraction in the correct order

1. Release of calcium

2. Release of acetylcholine

3. Myosin binding to actin

4. Depolarization reaches the t-tubules

2,4,1,3

Which of the following is true

Muscles that carry out fine motor movements are generally made up of motor units that contain only a few muscle fibers

False:

A single motor neuron can innervate only one muscle fiber

The muscle fiber composition of a motor unit is generally mixed (some slow-twitch, some fast-twitch fibers)

A single muscle fiber may be innervated by multiple motor neurons

Please arrange the events to a muscle contraction in the correct order

1. Calcium binds to troponin, causing tropomyosin to move

2. Depolarization of axon terminals

3. End plate potential in the muscle cell

4. The central nervous system sends a command in the form of a motor impulse

4,2,3,1

Which skeletal muscle fiber type has the lowest motor unit strength, the highest aerobic capacity, and highest fatigue resistance?

SO

Which of these is NOT true about skeletal muscle fibers?

The reuptake of calcium from the sarcoplasm after contraction uses passive transport

True:

Myoglobin is the oxygen transporting protein in muscles

FOG fibers are more fatigue resistant than type IIx

Myoglobin gives slow twitch muscles their dark red appearance

Which of these statements is NOT correct?

Troponin covers actin binding sites on myosin

Correct:

Cardiac muscle cells are striated

ATPase works with myosin to facilitate the power stroke of muscle contraction

Acetylcholine is the neurotransmitter between a motor neuron and a muscle fiber

The amount of force generated by a group of muscles depends on

The type of motor units recruited, the number of motor units recruited, the frequency of stimulation of motor units

Which athletes would you expect to have the highest percentage of SO fibers in her body?

Paula Radcliffe, a world record holder in the marathon

Other options:

Marion Jones, a world class sprinter and jumper

Inge de Brujn, a world record holder for the 50 m freestyle event in swimming

Gabriele Reinsch, a world record holder in discus

Which statement best describes the ramp theory of motor unit recruitment?

As the force requirement increases, type 1 motor units are activated first, the type 2A motor units, then type 2X motor units

Other options:

As the force requirement increases, a motor neuron will first active the slow twitch muscle cells it innervates, then the same motor neuron will activate the fast twitch A muscle cells it innervates, then the fast twitch X muscle cells

As the force requirement increases, type 2X motor units are activated first, then type 2A motor units, then type 1 motor units

As the force requirement increase, the type 2 motor units are activated unit they fatigue, then the type 1 motor units take over

A muscle action in which the muscle generates force but does not change in length is called

an isometric action

Which of these factors is most responsible for the muscle fiber type composition?

The DNA acquired for their parents

Other options:

The amount of resistance training an athlete does

The amount of endurance training an athlete does

Their dietary protein intake, theater from plant or animal

As you perform a maximal voluntary contraction, which statement accurately describes the interplay of motor unit recruitment and the motor unit rate of stimulation?

The first 30% of force production is accounted for by the recruitment of additional motor units, from 30-70% the increase in force production is due partly to increasing the rate of stimulation and partly due to recruitment of additional motor units, and from 70-100% the increase in force is due primarily to increasing the rate of stimulation

Based on your reading of "Enzyme activity and fiber composition in skeletal muscle of untrained and trained men" which statement about fiber type is NOT correct?

In response to resistance exercise, the ST fibers become larger than the FT fibers

True:

Endurance trained athletes have higher aerobic capacity in their type 1 and type 2 fibers than do strength and power athletes

Fast twitch muscle fibers were about 20% larger in diameter than were slow twitch muscle fibers

the muscle fibers, slow twitch and fast twitch, were larger in diameter in the trained subject than in the secondary subjects

What happens to a person's muscle fiber type composition as they age (particularly reading the senior citizen years)?

There is a loss of type 2 fibers, resulting in a higher percentage of their muscle fibers being type 1

The smallest contractile response of a muscle fiber or motor unit to a single electrical stimulus

twitch

A small bundle of muscle fibers wrapped in a connective tissue sheath within a muscle

Fascicle

A sheath of connective tissue that covers each muscle fiber

endomysium

A muscle fiber's cell membrane

Sarcolemma

Any muscle action that produces joint movement

dynamic contraction