Chapter 10 - 13 AP I

During the recovery period, the body's oxygen demand is:

elevated above normal resting levels

Nerves and blood vessels are contained within the connective tissues of the:

epimysium and perimysium

The hormone responsible for stimulating muscle metabolism and increasing the force of contraction during a sudden crisis is:

epinephrine

The type of skeletal muscle fibers that have low fatigue resistance are:

fast fibers

Which type of muscle fiber allows for extremely quick contractions but fatigues quickly?

fast fibers

When energy reserves in a muscle are exhausted and lactic acid levels increase, __________ occurs.

fatigue

Athletes training to develop anaerobic endurance perform:

frequent, brief, intensive workouts

At peak levels of muscle exertion, mitochondrial activity can provide about only one third of the ATP needed. The remainder is provided through

glycolysis.

On average, girls have smaller muscles and therefore less muscle mass than boys. Which hormones cause this difference between girls and boys?

growth hormone and testosterone

What human muscles contain only fast fibers?

hand muscles

Which of the following is an example of an isometric contraction?

holding a heavy stack of books above the ground

A muscle producing peak tension during rapid cycles of contraction and relaxation is said to be in:

incomplete tetanus

Smooth muscle contractions in the respiratory passageways cause:

increased resistance to air flow

The process of reaching complete tetanus is obtained by:

increasing the rate of stimulation until the relaxation phase is completely eliminated

The bacterium Clostridium tetani causes prolonged muscle contractions by doing which of the following?

inhibiting the mechanism that suppresses motor neuron activity

The junction between a muscle cell and the neuron innervating that cell is the

neuromuscular junction.

The amount of tension produced by an individual muscle fiber ultimately depends on the:

number of pivoting crossbridges

The major support that the muscular system gets from the cardiovascular system is:

nutrient and oxygen delivery and carbon dioxide removal

Layers of smooth muscle in the reproductive tract of the female are important in:

all of the above

You are observing a body in rigor mortis. Which panel best describes the molecular state of the body's muscles?

A Correct. This diagram depicts the formation of crossbridges.

When Jennifer looks through the microscope at skeletal and cardiac muscles, she sees striations. What are these striations?

A bands and I bands

The amount of tension produced in the skeletal muscle as a whole is determined by the:

all of the above

Which of the following is necessary for smooth muscle contraction?

Calcium ions must interact with calmodulin to trigger muscle contraction.

Which diagram represents actin-myosin interaction in the resting sarcomere?

C the myosin is reactive.

Which of the following could cause muscle atrophy?

all of the above

Which of the following would not be an effective source of energy for muscle contraction?

DNA

The part of the sarcomere that contains thick filaments but no thin filaments is the

H zone.

Which of the following statements about lactic acid and muscle fatigue is false?

Heat production in muscle tissue stops as soon as exercise activities cease.

The area of the A band in the sarcomere consists of:

M line, H band, zone of overlap

Cardiac muscle has the feature of automaticity, which is the ability to contract without neural stimulation. Which of the following statements accurately explains this unique feature?

Specialized pacemaker cells within the heart determine the rate of contraction of heart muscle.

Action potentials must travel along which structure internal to the sarcolemma to cause the release of calcium ions from the sarcoplasmic reticulum?

T tubules

CHAPTER 11

THE MUSCULAR SYSTEM

Which of the following descriptions of sarcomere components is false?

The I band contains the zone of overlap at its center.

The two mechanisms used to generate ATP from glucose are:

aerobic respiration and anaerobic glycolysis

Which of the following statements about muscle contraction is false?

When Ca2+ binds to a myosin head, it triggers the formation of a crossbridge between myosin and actin.

An example of an activity that requires anaerobic endurance is:

a 50-yard dash

Which of the following has been correlated with muscle fatigue?

a decline in pH within the muscle altering enzyme activities

The thick filaments consist of:

a helical array of myosin molecules

The thinfilaments consist of:

a pair of protein strands together to form chains of actin molecules

Which of the following represents the correct sequence of events in a contraction cycle?

active-site exposure, crossbridge attachment, pivoting, crossbridge detachment, myosin reactivation

The length of time a muscle can continue to contract while supported by mitochondrial activities is referred to as:

aerobic endurance

The level of activity at which the muscles must begin relying on anaerobic metabolism to meet its demands is called

anaerobic threshold.

A blending of epimysium, perimysium, and endomysium that forms a broad sheet at the end of a muscle is known as a(n):

aponeurosis

The order of the sequential-cyclic reactions that occur at an active site during cross-bridging is:

attach, pivot, detach, return

Mitochondrial activities are relatively efficient, but their rate of ATP generation is limited by the:

availability of oxygen

The cardiovascular system uses which types of muscle?

cardiac and smooth

Peak tension production occurs when all motor units in the muscle contract in a state of:

complete tetanus

Troponin and tropomyosin are two proteins that can prevent the contractile process by:

covering the active site and blocking the actin-myosin interaction

In an isotonic contraction, the:

crossbridges must produce enough tension to overcome the resistance

Which of the following events in a muscle contraction marks the beginning of the relaxation of the muscle cell?

detachment of crossbridges

In a(n) __________ contraction, the peak tension developed is less than the resistance, and the muscle elongates due to the contraction of another muscle or the pull of gravity.

eccentric

After contraction, a muscle fiber returns to its original length through:

elastic forces and the movement of opposing muscles

Excitation-contraction coupling forms the link between:

electrical activity in the sarcolemma and the initiation of a contraction

A feature found in cardiac muscle cells that is lacking in skeletal and smooth muscle cells is

intercalated discs.

Johnny, a 55-pound 6-year-old boy, wants to be as strong as some of the professional weight lifters he sees on television. He goes outside, grabs the front bumper of his mother's SUV, and attempts to raise it off the ground. The SUV does not move, but Johnny has succeeded in demonstrating which kind of muscle contraction?

isometric

Pushing against a locked door is an example of a(n)

isometric contraction.

Structurally, smooth muscle cells differ from skeletal muscle cells because smooth muscle cells:

lack myofibrils and sarcomeres

In anaerobic glycolysis, glucose is broken down to pyruvic acid, which is converted to:

lactic acid

When pyruvic acid is produced by anaerobic metabolism faster than it can be utilized, the surplus is converted to

lactic acid.

The phases of a single twitch, in sequential order, are:

latent period, contraction phase, relaxation phase

Skeletal muscle functions in

maintaining body temperature.

The reason that control over leg muscles is less precise than control over the muscles of the eye is:

many muscle fibers are controlled by a single motor neuron

Z lines

mark the boundaries between adjacent sarcomeres.

All of the muscle fibers controlled by a single motor neuron constitute a:

motor unit

What happens when the myosin head splits ATP into ADP and a phosphate group?

myosin reactivation

Which is a unique feature of smooth muscles?

plasticity

Which of the following does not happen when the action potential reaches the synaptic terminal?

potassium ions flood the intercellular space

Skeletal muscle is responsible for all of the following except

production of vitamin D.

The functional unit of the muscle fiber is a

sarcomere.

Repeating contractile units that make up a myofibril are called:

sarcomeres

The membranous network that surrounds each myofibril is the

sarcoplasmic reticulum.

A high blood concentration of the enzyme creatine phosphokinase (CPK) usually indicates:

serious muscle damage

The three types of muscle tissue are:

skeletal, cardiac, smooth

Extensive blood vessels, mitochondria, and myoglobin are found in the greatest concentration in:

slow fibers

Which type of muscle fiber is supplied by extensive blood vessels?

slow fibers

Which type of muscle fiber would be dominant in a muscle like the gastrocnemius, a calf muscle that contracts during standing and walking?

slow fibers

What type(s) of muscle tissue do(es) not contain sarcomeres?

smooth

The binding of ACh to the motor end plate causes a change in membrane permeability to

sodium.

The binding of calcium ions causes ACh to be released from what structure?

synaptic terminal

The transmission of an action potential along the T tubules stimulates the release of calcium from which structure in the sarcomere?

terminal cisternae

During moderate and peak exertion of skeletal muscles, the body experiences a higher temperature because of which of the following?

the reduction of energy captured by skeletal muscles as ATP during moderate and peak exertion

The sliding filament theory explains that the physical change that takes place during contraction is that:

the thin filaments are sliding toward the center of the sarcomere alongside the thick filaments

Skeletal muscles are often called voluntary muscles because:

they contract when stimulated by motor neurons of the central nervous system

The command to contract is conducted throughout the muscle fiber by the

transverse tubules.

For tropomyosin to be shifted off its position covering the active sites of G actin molecules, calcium ions must bind to which structure?

troponin `

In which part of the sarcomere are myosin heads able to form crossbridges with actin?

zone of overlap