Exam 3 Final

The increase in muscle tension that is produced by increasing the number of active motor units is called incomplete tetanus. treppe. complete tetanus. wave summation. recruitment.

recruitment

Excitation-contraction coupling is the sliding of thin filaments past thick filaments during muscle fiber contraction. sequence of processes that links the action potential to contraction. refractory period of an action potential. threshold period of an action potential. transfer of ACh into the synaptic cleft.

sequence of processes that links the action potential to contraction.

The narrow space between the synaptic terminal and the muscle fiber is the synaptic knob. M line. motor end plate. motor unit. synaptic cleft.

synaptic cleft

Which gluteal muscle is highlighted? gluteus maximus gluteus minimus gluteus internus gluteus medius

Gluteus maximus

Which of the following muscles would contract more forcefully? a muscle receiving 20 to 25 action potentials per second a muscle receiving 10 to 15 action potentials per second

a muscle receiving 20 to 25 action potentials per second

During the ________ phase of action potential development, voltage-gated sodium channels are open. repolarization threshold refractory depolarization

depolarization

Individual muscle cells are surrounded by what connective tissue? myofibrils sarcomere endomysium perimysium sarcolemma

endomysium

The dense layer of connective tissue that surrounds an entire skeletal muscle is the perimysium. fascicle. tendon. endomysium. epimysium.

epimysium

Synaptic vesicles containing neurotransmitters are released by ________ when the action potential arrives. endocytosis exocytosis apoptosis hydrolysis sodium

exocytosis

The synchronous contraction of a single motor unit is known as a(n) twitch. muscle action potential. cross-bridge. asynchronous motor unit summation. fasciculation.

fasciculation

Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of slow fibers. red muscles. intermediate fibers. fatty muscles. fast fibers.

fast fibers

Muscle fibers differ from "typical cells" in that muscle fibers lack a plasma membrane. lack mitochondria. are very small. have many nuclei. All of the answers are correct.

have many nuclei.

Muscular force can be adjusted to match increased loads by recruiting fewer motor units. decreasing the frequency of action potentials in motor neurons. increasing the frequency of action potentials in motor neurons. recruiting smaller motor units. None of the answers is correct.

increasing the frequency of action potentials in motor neurons.

Which muscle is highlighted? pectoralis major external oblique rectus abdominis internal oblique

internal oblique

The type of contraction in which the muscle fibers do not shorten is called concentric. isometric. isotonic. tetany. treppe.

isometric

The region of the sarcomere containing the thick and thin filaments is the H band. A band. M line. Z line. I band.

A band

Which statement about excitation-contraction coupling is incorrect? Tropomyosin moves to expose myosin binding sites on actin. Troponin binds calcium ion and signals tropomyosin to move. Calcium ion is released from the sarcoplasmic reticulum. Relaxation requires uptake of calcium ions by the sarcoplasmic reticulum. Calcium ion is released from the transverse tubule.

Calcium ion is released from the transverse tubule.

How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle? It would produce muscle weakness. It would cause spastic paralysis (muscles are contracted and unable to relax). It would cause flaccid paralysis (muscles are relaxed and unable to contract). It would make the muscles less excitable. It would have little effect on skeletal muscles.

It would cause spastic paralysis (muscles are contracted and unable to relax).

In a sarcomere, thick filaments are linked laterally by proteins of the M line. I band. Z line. A band. H band.

M line

Which of the following is an ion that is more concentrated inside the cell than outside? chloride sodium potassium calcium hydrogen

Potassium

What is the action of the highlighted muscle? depresses eyebrows raises eyebrows opens lips closes eyes

Raises eyebrows

Explain the relationship between load and speed of muscle contraction. (Module 9.11A) The greater the load on a muscle, the less time it takes for the muscle to shorten, and the more it shortens. The greater the load on a muscle, the longer it takes for the muscle to shorten, and the more it shortens. The greater the load on a muscle, the less time it takes for the muscle to shorten, and the less it shortens. The greater the load on a muscle, the longer it takes for the muscle to shorten, and the less it shortens. There is no relationship between load and speed of muscle contraction.

The greater the load on a muscle, the longer it takes for the muscle to shorten, and the less it shortens.

During anaerobic glycolysis, which of the following does not occur? ATP is produced. Lactate is produced. Pyruvate is produced. Oxygen is not consumed. The mitochondria are required.

The mitochondria are required.

What is thought to happen in a muscle during the response shown in graph (a)? It is fatigued and must make repeated efforts to twitch normally. It is strengthening with exercise. It is aged and has lost contractile proteins. There is a gradual increase in the concentration of calcium ions in the sarcoplasm. It is producing more ATP as tension increases.

There is a gradual increase in the concentration of calcium ions in the sarcoplasm.

Triggering of the muscle action potential occurs after the nerve action potential jumps across the neuromuscular junction. acetylcholine binds to chemically gated channels in the motor end plate membrane. acetylcholinesterase binds to receptors on the end plate. calcium ion binds to channels on the end plate. Any of these actions can produce an action potential in the muscle cell.

acetylcholine binds to chemically gated channels in the motor end plate membrane.

The cytoplasm of the neuromuscular synaptic terminal contains vesicles filled with molecules of the neurotransmitter norepinephrine. acetylcholinesterase. acetylcholine. antidiuretic hormone. epinephrine.

acetylcholine.

During the recovery period, the body's need for oxygen is increased because the liver requires more oxygen to produce lactic acid. muscle cells are producing energy anaerobically. the individual is panting. the muscles are not producing ATP. additional oxygen is required to restore energy reserves consumed during exercise.

additional oxygen is required to restore energy reserves consumed during exercise.

A resting muscle generates most of its ATP by glycogenolysis. anaerobic respiration. hydrolysis of creatine phosphate. the tricarboxylic acid cycle. aerobic metabolism of fatty acids.

aerobic metabolism of fatty acids.

After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs. paralysis an oxygen debt treppe atrophy tetanus

an oxygen debt

When comparing slow fibers to fast fibers, slow fibers appear dark red. have much larger fiber diameters. take less time to reach peak tension. generate much more tension. are lacking myoglobin.

appear dark red.

What is released from the structure labeled "9"? calcium ions acetylcholine sodium acetylcholinesterase proteins

calcium ions

When a muscle is stimulated repeatedly at a high rate, eliminating a relaxation phase, the amount of tension gradually increases to a steady maximum tension. This is called incomplete tetanus. complete tetanus. a twitch. wave summation. recruitment.

complete tatanus.

Physical evidence that supports the sliding filament theory of muscle contraction includes the I band and H band distance is constant during contraction. constant distance between Z lines during contraction. decreased width of the H band during contraction. increased width of the I band during contraction. decreased width of the A band during contraction.

decreased width of the H band during contraction.

Na+ and K+ both use ________ to passively diffuse across the plasma membrane. exocytosis voltage-gated channels carrier-mediated transport leak channels facilitated diffusion

leak channels

The muscle weakness of myasthenia gravis results from insufficient acetylcholine release from presynaptic vesicles. the motor neuron action potential being too small to shock the muscle fibers. excessive acetylcholinesterase that destroys the neurotransmitter. loss of acetylcholine receptors in the end-plate membrane. All of the answers probably contribute to the muscle weakness.

loss of acetylcholine receptors in the end-plate membrane.

Cellular membrane potential is measured in millivolts. micrometers. Hertz. milliseconds. amperes.

millivolts.

During activities requiring aerobic endurance, most of the muscle's energy is produced in mitochondria. glycogen and glycolysis are the primary sources of reserve energy. oxygen is not required. fatigue occurs in a few minutes. oxygen debts are common.

most of the muscle's energy is produced in mitochondria.

Neurons and ________ have electrically excitable membranes that propagate action potentials. dense connective tissue proteins epithelial cells muscle cells osteocytes

muscle cells

To produce a contraction similar to the one in graph (b), the muscle must be stimulated to the point of fatigue. is excited by a stimulus of increasing intensity. gradually warms up. is caused to produce isolated twitches. must be stimulated again before it has relaxed from the previous stimulation.

must be stimulated again before it has relaxed from the previous stimulation.

Name the proteins that make up a thick filament. (Module 9.4B) myosin and titin actin and titin actin and dystrophin myosin and nebulin actin and nebulin

myosin and titin

At peak levels of muscle exertion, the mitochondria can supply ________ of the energy required by the muscle. all 80 percent only about one-third only about 10 percent more than half

only about one-third

Of the following clinical conditions affecting skeletal muscle, which is caused by a virus? botulism tetanus Duchenne muscular dystrophy rigor mortis polio

polio

Fast muscle fibers can adapt to aerobic metabolism by generating more mitochondria in response to repeated, exhaustive stimulation. increased levels of testosterone. prolonged periods of inactivity. sustained low levels of muscle activity. high amounts of oxygen.

repeated, exhaustive stimulation.

Which structure is highlighted? ribs and costal cartilage internal oblique muscle sternum external intercostal muscle

ribs and coastal cartilage

After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as depolarization. treppe. rigor mortis. oxygen debt. tetany.

rigor mortis

The plasma membrane of skeletal muscle is called the sarcoplasm. sarcomere. sarcoplasmic reticulum. sarcosome. sarcolemma.

sarcolemma

The structural explanation of how a muscle fiber contracts is called the thin filament theory. myosin spiral theory. active site rule. sliding filament theory. cross-bridge connection.

sliding filament theory.

The type of muscle fiber that is most resistant to fatigue is the ________ fiber. fast high-density anaerobic slow intermediate

slow

Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass? parathyroid hormone testosterone epinephrine calcitonin thyroid hormone

testosterone

Which of the following is greater? the concentration of calcium ion in the sarcoplasmic reticulum of a resting muscle the concentration of calcium ion in the sarcoplasm of a resting muscle

the concentration of calcium ion in the sarcoplasmic reticulum of a resting muscle

Which of the following become connected by myosin cross-bridges during muscle contraction? thick filaments and T tubules Z disks and actin filaments thick filaments and titin filaments thin filaments and thick filaments thin filaments and T tubules

thin filaments and thick filaments

The action potential is conducted into a skeletal muscle fiber by sarcoplasmic reticulum. transverse tubules. motor end plates. neuromuscular junctions. triads.

transverse tubules.

At rest, active sites on the actin are blocked by calcium ions. tropomyosin molecules. ATP molecules. myosin molecules. troponin molecules.

tropomyosin molecules

When calcium ion binds to troponin, tropomyosin moves into the groove between the helical actin strands. troponin shifts to expose the active sites on actin. myosin shortens. muscle relaxation occurs. active sites on the myosin are exposed.

tropomyosin moves into the groove between the helical actin strands.

If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called incomplete tetanus. complete tetanus. treppe. wave summation. recruitment.

wave summation