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