The ______ is connected to the hypothalamus by a collection of nerve axons whose cell bodies are in the hypothalamus.

The ______ is connected to the hypothalamus by a collection of nerve axons whose cell bodies are in the hypothalamus.

Answer: Posterior lobe

Positive feedback is not common in the endocrine system and is self- ____.

Positive feedback is not common in the endocrine system and is self- ____.

Answer: self augmenting

The ____ and Pituitary gland act in coordination to carry out many functions of the endocrine system.

The ____ and Pituitary gland act in coordination to carry out many functions of the endocrine system.

Answer: hypothalamus.

During the recovery period the body's need for oxygen is increased because

During the recovery period the body's need for oxygen is increased because

a) the liver requires more oxygen to produce lactic acid.

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

c) the individual is panting.

d) muscle cells are producing energy anaerobically.

e) the muscles are not producing ATP.

Answer: B

Which of the following is not a type of motor unit?

Which of the following is not a type of motor unit?

a) whiteslow twitch

b) redfast twitch

c) whitefast twitch

d) redslow twitch

e) All of these are well known.

Answer: A

Each skeletal muscle fiber is controlled by a motor neuron at a single

Each skeletal muscle fiber is controlled by a motor neuron at a single

a) synaptic knob.

b) synaptic cleft.

c) sarcomere.

d) transverse tubule.

e) neuromuscular junction.

Answer: E

How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?

How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?

a) It would have little effect on skeletal muscles.

b) It would make the muscles less excitable.

c) It would produce muscle weakness.

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

e) It would cause flaccid paralysis (muscles are relaxed and unable to contract).

Answer: D

Compared to a "typical" body cell, skeletal muscle cells are

Compared to a "typical" body cell, skeletal muscle cells are

a) multinucleate.

b) filled with crystalline 3-D arrays of fibrous proteins.

c) larger than normal cells.

d) capable of rapid shortening against a load.

e) all of the above

Answer: E

The region of the sarcomere that always contains thin filaments is the

The region of the sarcomere that always contains thin filaments is the

a) A band.

b) M line.

c) I band.

d) Z line.

e) H band.


Answer: C

Creatine phosphate

Creatine phosphate

a) is only formed during strenuous exercise.

b) can replace ATP in binding to myosin molecules during contraction.

c) is produced by the process of anaerobic respiration.

d) cannot transfer its phosphate group to ADP.

e) acts as an energy reserve in muscle tissue.

Answer: E

The type of contraction in which the muscle fibers do not shorten is called

The type of contraction in which the muscle fibers do not shorten is called

a) tetany.

b) isometric.

c) treppe.

d) concentric.

e) isotonic.



Answer: B

Fast fibers

Fast fibers

a) have low resistance to fatigue.

b) rely on aerobic metabolism.

c) have many mitochondria.

d) have twitches with a very brief contraction phase.

e) both A and D

Answer: E

During anaerobic glycolysis

During anaerobic glycolysis

a) pyruvic acid is produced.

b) oxygen is not consumed.

c) ATP is produced.

d) all of the above

e) B and C only

Answer: D

During the recovery period following exercise, all of the following are true, except

During the recovery period following exercise, all of the following are true, except

a) oxygen is consumed at above the resting rate.

b) lactic acid is removed from muscle cells.

c) muscle fibers are unable to contract.

d) heat is generated.

e) the muscle actively produces ATP.

Answer: C

Calcium ions are binding to troponin during the ________ of a muscle twitch.

Calcium ions are binding to troponin during the ________ of a muscle twitch.

a) latent period

b) contraction phase

c) relaxation phase

d) recovery phase

e) both A and B

Answer: E

Fast muscle fibers can adapt to aerobic metabolism by generating more mitochondria in response to

Fast muscle fibers can adapt to aerobic metabolism by generating more mitochondria in response to

a) sustained low levels of muscle activity.

b) high amounts of oxygen.

c) repeated, exhaustive stimulation.

d) prolonged periods of inactivity.

e) increased levels of testosterone.

Answer: C

Cross-bridges are portions of

Cross-bridges are portions of

a) myosin molecules.

b) actin molecules.

c) troponin molecules.

d) tropomyosin molecules.

e) calcium ions.

Answer: A

How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle?

How would a drug that blocks acetylcholine receptors at the motor end plate affect skeletal muscle?

a) It would have little effect on skeletal muscles.

b) It would produce uncontrolled muscle spasms.

c) It would cause flaccid paralysis (muscles are relaxed and unable to contract).

d) It would make the muscles more excitable.

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

Answer: C

Receptors for acetylcholine are located on the

Receptors for acetylcholine are located on the

a) transverse tubule.

b) synaptic knob.

c) sarcomere.

d) synaptic cleft.

e) motor end plate.

Answer: E

When calcium ion binds to troponin,

When calcium ion binds to troponin,

a) muscle relaxation occurs.

b) tropomyosin moves into the groove between the helical actin strands.

c) active sites on the myosin are exposed.

d) actin heads will bind to myosin.

e) myosin shortens.

Answer: B

In a sarcomere, thick filaments are linked laterally by proteins of the

In a sarcomere, thick filaments are linked laterally by proteins of the

a) H band.

b) Z line.

c) I band.

d) M line.

e) A band.

Answer: D

The thin filaments of striated muscle are made of which protein(s)?

The thin filaments of striated muscle are made of which protein(s)?

a) troponin

b) actin

c) tropomyosin

d) nebulin

e) all of the above

Answer: E

Which of the following statements is false?

Which of the following statements is false?

a) Skeletal muscle stimulation is neural.

b) Cardiac muscle stimulation is neural.

c) Skeletal muscle contractions may be summated.

d) Cardiocytes are interconnected through intercalated discs.

e) Cardiac muscle contractions cannot be summated.

Answer: B

During activities requiring aerobic endurance

During activities requiring aerobic endurance

a) oxygen debts are common.

b) oxygen is not required.

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

d) fatigue occurs in a few minutes.

e) glycogen and glycolysis are the primary sources of reserve energy.

Answer: C

The narrow space between the synaptic terminal and the muscle fiber is the

The narrow space between the synaptic terminal and the muscle fiber is the

a) motor unit.

b) synaptic cleft.

c) M line.

d) synaptic knob.

e) motor end plate.

Answer: B

Which of the following best describes the term Z line?

Which of the following best describes the term Z line?

a) thin filaments are anchored here

b) protein that accounts for elasticity of resting muscle

c) largely made of myosin molecules

d) repeating unit of striated myofibrils

e) storage site for calcium ions



Answer: A

At peak levels of muscle exertion the mitochondria can supply

At peak levels of muscle exertion the mitochondria can supply

a) all of the energy required by the muscle.

b) more than half of the energy required by the muscle.

c) 80 percent of the energy required by the muscle.

d) only about 10 percent of the energy required by the muscle.

e) only about one-third of the energy required by the muscle.

Answer: E

When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension. This is called

When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension. This is called

a) recruitment.

b) complete tetanus.

c) incomplete tetanus.

d) wave summation.

e) a twitch.


Answer: B

The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter

The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter

a) acetylcholine.

b) antidiuretic hormone.

c) norepinephrine.

d) epinephrine.

e) all of the above

Answer: A

Each thin filament consists of

Each thin filament consists of

a) chains of myosin molecules.

b) a rod-shaped structure with "heads" projecting from each end.

c) a double strand of myosin molecules.

d) two protein strands coiled helically around each other.

e) six molecules coiled into a helical structure.

Answer: D

Which of the following best describes the term sarcoplasmic reticulum?

Which of the following best describes the term sarcoplasmic reticulum?

a) thin filaments are anchored here

b) protein that accounts for elasticity of resting muscle

c) largely made of myosin molecules

d) repeating unit of striated myofibrils

e) storage and release site for calcium ions

Answer: E

The following is a list of the events that occur during a muscle contraction.

The following is a list of the events that occur during a muscle contraction.

1. Myosin cross-bridges bind to the actin.
2. The free myosin head splits ATP.
3. Calcium ion is released from the sarcoplasmic reticulum.
4. The myosin head pivots toward the center of the sarcomere.
5. Calcium ion binds to troponin.
6. The myosin head binds an ATP molecule and detaches from the actin.

The correct sequence of these events is


a) 1, 3, 5, 4, 6, 2.

b) 3, 5, 1, 4, 6, 2.

c) 5, 1, 4, 6, 2, 3.

d) 1, 4, 6, 2, 3, 5.

e) 3, 5, 1, 2, 4, 6.

Answer: B

In which of the following would the motor units have the fewest muscle fibers?

In which of the following would the motor units have the fewest muscle fibers?

a) muscles that control the eyes

b) postural muscles of the back

c) calf muscles

d) thigh muscles

e) muscles of the neck

Answer: A

Which of the following become connected by myosin cross-bridges during muscle contraction?

Which of the following become connected by myosin cross-bridges during muscle contraction?

a) thin filaments and t-tubules

b) thin filaments and thick filaments

c) thick filaments and t-tubules

d) thick filaments and titin filaments

e) z disks and actin filaments

Answer: B

Synaptic vesicles containing neurotransmitters are released by ________ when the action potential arrives.

Synaptic vesicles containing neurotransmitters are released by ________ when the action potential arrives.

a) apoptosis

b) exocytosis

c) hydrolysis

d) endocytosis

e) sodium

Answer: B

Which of the following best describes the term titin?

Which of the following best describes the term titin?

a) protein that accounts for elasticity of resting muscle

b) repeating unit of striated myofibrils

c) thin filaments are anchored here

d) largely made of myosin molecules

e) storage site for calcium ions

Answer: A

At rest, the tropomyosin molecule is held in place by

At rest, the tropomyosin molecule is held in place by

a) actin molecules.

b) troponin molecules.

c) myosin molecules.

d) calcium ions.

e) ATP molecules.


Answer: B

Which statement about the microscopic anatomy of skeletal muscle fibers is true?

Which statement about the microscopic anatomy of skeletal muscle fibers is true?

a) Muscle fibers are continuous from tendon to tendon.

b) Tubular extensions of the sarcolemma penetrate the fiber transversely.

c) Each fiber has many nuclei.

d) Cross striations result from the lateral alignment of thick and thin filaments.

e) All are true.

Answer: E

The muscle weakness of myasthenia gravis results from

The muscle weakness of myasthenia gravis results from

a) insufficient acetylcholine release from presynaptic vesicles.

b) the motor neuron action potential being too small to shock the muscle fibers.

c) loss of acetylcholine receptors in the end-plate membrane.

d) excessive acetylcholinesterase that destroys the neurotransmitter.

e) All of the above probably contribute to the weakness.

Answer: C

A resting muscle generates most of its ATP by

A resting muscle generates most of its ATP by

a) aerobic metabolism of fatty acids.

b) the tricarboxylic acid cycle.

c) glycogenolysis.

d) anaerobic respiration.

e) hydrolysis of creatine phosphate.

Answer: A

The area in the center of the A band that contains no thin filaments is the

The area in the center of the A band that contains no thin filaments is the

a) H band.

b) zone of overlap.

c) M line.

d) Z line.

e) I band.

Answer: A

The skeletal muscle complex known as the triad consists of

The skeletal muscle complex known as the triad consists of

a) filaments, myofibrils, and sarcomeres.

b) actin, myosin, and sarcomeres.

c) a transverse tubule and two terminal cisternae.

d) A bands, H bands, and I bands.

e) actin, myosin, and filaments.

Answer: C

A muscle producing tension that peaks and falls at intermediate stimulus rates is said to be in

A muscle producing tension that peaks and falls at intermediate stimulus rates is said to be in

a) complete tetanus.

b) recruitment.

c) treppe.

d) wave summation.

e) incomplete tetanus.

Answer: E

Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of

Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of

a) fatty muscles.

b) slow fibers.

c) fast fibers.

d) red muscles.

e) intermediate fibers.




Answer: C

A single motor neuron together with all the muscle fibers it innervates is called

A single motor neuron together with all the muscle fibers it innervates is called

a) a motor unit.

b) an end foot.

c) a myotome.

d) a dermatome.

e) an end plate.

Answer: A

Skeletal muscle fibers are formed from embryonic cells called

Skeletal muscle fibers are formed from embryonic cells called

a) myofibrils.

b) myoblasts.

c) fascicles.

d) myomeres.

e) sarcomeres.

Answer: B

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for

a) contraction.

b) conduction.

c) peristalsis.

d) cushioning

e) any of the above

Answer: A

The most important factor in decreasing the intracellular concentration of calcium ion after contraction is

The most important factor in decreasing the intracellular concentration of calcium ion after contraction is

a) diffusion of calcium out of the cell.

b) active transport of calcium into the sarcoplasmic reticulum.

c) active transport of calcium across the sarcolemma.

d) active transport of calcium into the synaptic cleft.

e) diffusion of calcium into the sarcoplasmic reticulum.

Answer: B

Active sites on the actin become available for binding after

Active sites on the actin become available for binding after

a) myosin binds to troponin.

b) troponin binds to tropomyosin.

c) calcium binds to troponin.

d) calcium binds to tropomyosin.

e) actin binds to troponin.

Answer: C

Which of the following acts as an ATPase during the contraction cycle of muscle?

Which of the following acts as an ATPase during the contraction cycle of muscle?

a) tropomyosin molecules

b) troponin molecules

c) actin molecules

d) the tail portion of the myosin molecule

e) the head portion of the myosin molecule

Answer: E

Which of the following is not characteristic of smooth muscle?

Which of the following is not characteristic of smooth muscle?

a) The thin filaments of smooth muscle fibers are attached to dense bodies.

b) Neurons that innervate smooth muscles are under involuntary control.

c) Smooth muscle connective tissue forms tendons and aponeuroses.

d) Smooth muscles are uninucleate.

e) Smooth muscles do not contain sarcomeres.

Answer: C

If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called

If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This is called

a) incomplete tetanus.

b) complete tetanus.

c) recruitment.

d) treppe.

e) wave summation.

Answer: E

The plasma membrane of skeletal muscle is called the

The plasma membrane of skeletal muscle is called the

a) sarcolemma.

b) sarcoplasm.

c) sarcoplasmic reticulum.

d) sarcomere.

e) sarcosome.

Answer: A

Which of the following statements is (are) true regarding human muscles?

Which of the following statements is (are) true regarding human muscles?

a) Slow fibers are abundant in the calf muscles.

b) Eye muscles are composed entirely of fast fibers.

c) Most have both slow and fast fibers.

d) Slow fibers are abundant in the back muscles.

e) All of the above.

Answer: E

The advantage of having many nuclei in a skeletal muscle fiber is

The advantage of having many nuclei in a skeletal muscle fiber is

a) the ability to produce more ATP with little oxygen.

b) the ability to contract.

c) the ability to produce large amounts of the muscle proteins needed for growth and repair.

d) the ability to store extra DNA for metabolism.

e) both C and D

Answer: C

In an isotonic contraction,

In an isotonic contraction,

a) tension rises and falls but the muscle length is constant.

b) the peak tension is less than the load.

c) flexion is produced.

d) many twitches fuse into one.

e) muscle tension exceeds the load and the muscle lifts the load.

Answer: E

The increase in muscle tension that is produced by increasing the number of active motor units is called

The increase in muscle tension that is produced by increasing the number of active motor units is called

a) incomplete tetanus.

b) recruitment.

c) treppe.

d) wave summation.

e) complete tetanus.


Answer: B

The type of muscle fiber that is most resistant to fatigue is the ________ fiber.

The type of muscle fiber that is most resistant to fatigue is the ________ fiber.

a) high-density

b) anaerobic

c) slow

d) fast

e) intermediate

Answer: C

Muscle fibers differ from "typical cells" in that muscle fibers

Muscle fibers differ from "typical cells" in that muscle fibers

a) have many nuclei.

b) are very small.

c) lack a plasma membrane.

d) lack mitochondria.

e) both B and C

Answer: A

At rest, active sites on the actin are blocked by

At rest, active sites on the actin are blocked by

a) troponin molecules.

b) myosin molecules.

c) ATP molecules.

d) calcium ions.

e) tropomyosin molecules.

Answer: E

In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases

In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases

a) hydrogen ions.

b) acetylcholine.

c) calcium ions.

d) potassium ions.

e) sodium ions.



Answer: C

The rapid rise and fall in force produced by a muscle fiber after a single action potential is

The rapid rise and fall in force produced by a muscle fiber after a single action potential is

a) a tetanus.

b) an end plate potential.

c) an unfused tetanus.

d) a twitch.

e) a muscle action potential.

Answer: D

Which of the following best describes the term sarcomere?

Which of the following best describes the term sarcomere?

a) largely made of myosin molecules

b) repeating unit of striated myofibrils

c) thin filaments are anchored here

d) protein that accounts for elasticity of resting muscle

e) storage site for calcium ions

Answer: B

After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs.

After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs.

a) treppe

b) paralysis

c) atrophy

d) tetanus

e) an oxygen debt

Answer: E

Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass?

Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass?

a) calcitonin

b) testosterone

c) parathyroid hormone

d) thyroid hormone

e) epinephrine



Answer: B

When comparing slow motor units to fast motor units, slow units

When comparing slow motor units to fast motor units, slow units

a) take about three times as long to reach peak tension.

b) have much smaller fiber diameters.

c) are rich in the red protein myoglobin.

d) generate much less tension.

e) all of the above

Answer: E

When a skeletal muscle fiber contracts,

When a skeletal muscle fiber contracts,

a) the zones of overlap get larger.

b) the Z lines get closer together.

c) the width of the A band remains constant.

d) the H bands and I bands get smaller.

e) all of the above

Answer: E

The action potential is conducted into a skeletal muscle fiber by

The action potential is conducted into a skeletal muscle fiber by

a) neuromuscular junctions.

b) motor end plates.

c) transverse tubules.

d) triads.

e) sarcoplasmic reticulum.

Answer: C

When acetylcholine binds to receptors at the motor end plate, the end plate membrane becomes

When acetylcholine binds to receptors at the motor end plate, the end plate membrane becomes

a) less permeable to potassium ions.

b) more permeable to calcium ions.

c) less permeable to sodium ions.

d) repolarized.

e) more permeable to sodium ions.

Answer: E

Muscular force can be adjusted to match different loads by

Muscular force can be adjusted to match different loads by

a) recruiting larger motor units

b) varying the frequency of action potentials in motor neurons

c) recruiting more motor units

d) A, B, and C

e) None of the above muscle contraction is all-or-none.

Answer: D