Exercise Physio CH08

The breakdown of ATP in muscle is accomplished via the enzyme

myosin ATPase

Disease-related muscle wasting is termed

cachexia

The amount of force exerted during muscular contraction is dependent on the

type of motor units recruited, the initial length of the muscle, and the nature of the neural stimulation

The two major contractile proteins found in skeletal muscle are

actin and myosin

The cell membrane around a muscle fiber is called the

sarcolemma

Skeletal muscle fibers that contain a large volume of mitochondria are likely

type I fibers

Satellite cells

-contribute to muscle growth by dividing and contributing nuclei to existing muscle fibers.

-reside above the sarcolemma.

-are undifferentiated cells that play a key role in muscle growth and repair.

-All of these answers are correct.

All of these answers are correct

One of the proposed mechanisms to explain the positive impact of post-activation potential on muscle performance is that low-intensity muscle contractions result in phosphorylation of myosin light chains (i.e., proteins located at the base of the myosin cross-bridge). This increased phosphorylation can increase muscle force production by

increasing the muscle's sensitivity to calcium.

The connecting point between a motor neuron and muscle fiber is called the

neuromuscular junction

The peak power generated by any skeletal muscle increases with increasing velocities of movement up to a movement speed of 200-300 degrees per second; at higher shortening velocities, the peak power output declines. Which of the following factors can explain this observation?

Muscle force production decreases with high shortening velocities because fewer cross-bridges are connected and therefore, less force is produced

Fast-twitch fibers (i.e., type IIx) contain a relatively

small number of mitochondria and high ATPase activity

Exercise-induced muscle cramps in a single muscle results from dehydration and blood electrolyte imbalance. Which of the following observations DO NOT support this position?

-Dehydration and electrolyte imbalance would likely impact all skeletal muscles.

-Exercise-induced muscle cramps can occur without any change in blood electrolyte concentrations.

-Static stretching of the cramping muscle often relieves the cramp.

-All of these answers are correct.

All of these answers are correct.

The formation of cross-bridges that initiate the contractile process in skeletal muscle is triggered by

calcium binding to troponin

What is true about muscle fatigue?

"The cause of muscle fatigue during severe exercise is multifactorial and includes increases in phosphate ions and hydrogen ions within the active muscle fibers." and "Increases in hydrogen ions in skeletal muscle contribute to fatigue because hydrogen ions bind to the calcium-binding site on troponin."

A muscular contraction that results in a movement of body parts is called a(n)

dynamic contraction

Which of the following events occur FIRST to initiate a voluntary muscle contraction?

The innervating alpha-motor neuron reaches an action potential

A highly successful endurance athlete would likely have _________ compared to a sedentary individual.

a higher percentage of type I fibers

The force-velocity curve describes the relationship between speed of muscle shortening (i.e., velocity of movement) and muscle force production. Which of the following statements are true about the influence of muscle fiber type on the force-velocity curve?

At any given velocity of movement, the peak power generated is greater in a muscle that contains a high percentage of fast fibers (i.e., type IIx) compared with a muscle that contains a high percentage of slow fibers (i.e., type I).

Four categories (domains) of exercise intensity exist. What about exercise intensity domains are true?

"Moderate-intensity exercise is below the lactate threshold and typically below 60% VO2 max in untrained subjects" and "Heavy exercise is exercise above the lactate threshold and typically ranges between 60-75% VO2 max"

The layer of connective tissue that surrounds the outside of skeletal muscle (i.e., just below the fascia) is called the

epimysium

Aging is associated with a loss of muscle mass; this is called sarcopenia. Which of the following statements about sarcopenia are correct?

-The slow phase of age-related muscle decline ranges from age 25 to 50 years

-Muscle mass begins to decline around age 25

-By age 80, 50% of the total muscle mass can be lost

-All of these answers are correct.

All of these answers are correct

Postactivation potentiation is defined as

the increase in muscle force production that occurs following a bout of non-fatiguing, submaximal contractions (ex: warmup exercises)

The specific tension (i.e., force production per cross-sectional area of the fiber) differs between fiber types. Which of the following answers is correct relative to specific force production?

-type I is greater than type IIa and IIx

-type IIx is greater than type I and IIa

-Both "type IIx is greater than type I and IIa" and "type IIx is slightly greater than type IIa" are correct.

-type IIx is slightly greater than type IIa

Both "type IIx is greater than type I and IIa" and "type IIx is slightly greater than type IIa" are correct

The motor neuron and all the muscle fibers it innervates is called a

motor unit

Which type of muscle fiber has been shown to be the most efficient?

type I

Calcium is stored in muscle within the

sarcoplasmic reticulum

Which of the following metabolites have been shown to cause muscle fatigue?

-the accumulation H+

-Both "the accumulation H+" and "the accumulation of inorganic phosphate" are correct.

-the accumulation of inorganic phosphate

-a rise in ADP

Both "the accumulation H+" and "the accumulation of inorganic phosphate" are correct

Which of the following statements about the myonuclear domain are correct?

-The myonuclear domain is the region of cytoplasm surrounding an individual nucleus.

-All of these answers are correct.

-The significance of the myonuclear domain is that a single nucleus is responsible for the gene expression for its surrounding cytoplasm.

-In response to resistance exercise, satellite cells become activated and divide to add additional nuclei to a muscle fiber.

All of these answers are correct