A&P I 2014 Exam 3a Name ______________________________________

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

A) acetylcholine.

B) sodium ions.

C) potassium ions.

D) calcium ions.

E) hydrogen ions.

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

A) synaptic knob.

B) sarcomere.

C) neuromuscular junction.

D) synaptic cleft.

E) transverse tubule.

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

A) synaptic knob.

B) motor end plate.

C) motor unit.

D) synaptic cleft.

E) M line.

4) Active sites on the actin become available for binding after

A) actin binds to troponin.

B) troponin binds to tropomyosin.

C) calcium binds to troponin.

D) calcium binds to tropomyosin.

E) myosin binds to troponin.

5) Receptors for acetylcholine are located on the

A) synaptic knob.

B) motor end plate.

C) sarcomere.

D) synaptic cleft.

E) transverse tubule.

6) The action potential is conducted into a skeletal muscle fiber by

A) motor end plates.

B) neuromuscular junctions.

C) transverse tubules.

D) triads.

E) sarcoplasmic reticulum.

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

A) active transport of calcium across the sarcolemma.

B) active transport of calcium into the sarcoplasmic reticulum.

C) active transport of calcium into the synaptic cleft.

D) diffusion of calcium out of the cell.

E) diffusion of calcium into the sarcoplasmic reticulum.

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

A) actin molecules

B) troponin molecules

C) tropomyosin molecules

D) the head portion of the myosin molecule

E) the tail portion of the myosin molecule

9) When calcium ion binds to troponin,

A) tropomyosin rolls away from the active site.

B) active sites on the myosin are exposed.

C) actin heads will bind to myosin.

D) muscle relaxation occurs.

E) myosin shortens.

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

A) thin filaments and thick filaments

B) thick filaments and titin filaments

C) z disks and actin filaments

D) thick filaments and t-tubules

E) thin filaments and t-tubules

11) 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

A) tetany.

B) treppe.

C) depolarization.

D) rigor mortis.

E) oxygen debt.

12) In rigor mortis

A) the myosin heads are attached to actin.

B) ATP is depleted.

C) calcium ions keep binding to troponin.

D) sustained contractions occur.

E) All of the answers are correct.

13) In a sarcomere, cross-bridge attachment occurs specifically in the

A) zone of overlap.

B) A band.

C) I band.

D) M line.

E) H band.

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

A) epinephrine.

B) norepinephrine.

C) acetylcholine.

D) antidiuretic hormone.

E) adrenaline.

15) At what point during excitation contraction coupling does exocytosis play a role?

A) during calcium ion reuptake into the sarcoplasmic reticulum

B) when sodium channels open up on the motor end plate

C) during acetylcholine release from the synaptic terminal

D) when the action potential surges through the T-tubules

E) when ATP splits into ADP and P on the free myosin head

16) Which of the following statements about excitation-contraction coupling is incorrect?

A) Calcium ions travel through the transverse tubule.

B) Calcium ion is released from the sarcoplasmic reticulum.

C) Tropomyosin moves to expose myosin binding sites on actin.

D) Troponin binds calcium ion and signals tropomyosin to move.

E) Relaxation requires uptake of calcium ion by the sarcoplasmic reticulum.

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

A) incomplete tetanus.

B) complete tetanus.

C) treppe.

D) wave summation.

E) recruitment.

18) If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This addition of one twitch to another is called

A) incomplete tetanus.

B) complete tetanus.

C) treppe.

D) wave summation.

E) recruitment.

19) A single motor neuron together with all the muscle fibers it innervates is called a(n)

A) end foot.

B) end plate.

C) motor unit.

D) dermatome.

E) myotome.

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

A) incomplete tetanus.

B) complete tetanus.

C) treppe.

D) wave summation.

E) recruitment.

21) A weight-lifter strains to lift a heavy weight and there is no movement of the person's arms holding on to the weight. This type of contraction is called a(n) ________ contraction.

A) isometric

B) tetanus

C) isotonic

D) treppe

E) concentric

Figure 10-2 Muscle Contractions

Use Figure 10-2 to answer the following questions:

22) What is the contraction in graph (a) called?

A) complete tetanus

B) incomplete tetanus

C) twitch

D) wave summation

E) treppe

23) What is thought to happen in a muscle during the response shown in graph (a)?

A) It is strengthening with exercise.

B) There is a gradual increase in calcium ion concentration in the sarcoplasm.

C) It is fatigued and must make repeated efforts to twitch normally.

D) It is aged and has lost contractile proteins.

E) It is producing more ATP as tension increases.

24) To produce a contraction similar to the one in graph (b), the muscle

A) must be stimulated to the point of fatigue.

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

C) is excited by a stimulus of increasing intensity.

D) must go through a rapid series of isolated twitches.

E) generates more and more thin and thick filaments.

25) Why is there partial relaxation in graph (c)?

A) Calcium ion release is slow.

B) The muscle is starting to fatigue.

C) Stimulation intensity is fluctuating.

D) ATP reserves are cycling.

E) Nerve stimulation frequency is below maximum.

26) What is the contraction in graph (d) called?

A) complete tetanus

B) incomplete tetanus

C) twitch

D) wave summation

E) treppe

Multiple Choice

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

A) muscle cells are producing ATP anaerobically.

B) creatine phosphate stimulates mitochondrial activity.

C) additional oxygen is required to restore energy reserves.

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

E) the muscles produce much less ATP.

28) A resting muscle generates most of its ATP by

A) hydrolysis of creatine phosphate.

B) anaerobic respiration.

C) aerobic metabolism of fatty acids.

D) glycogenolysis.

E) the tricarboxylic acid cycle.

29) Creatine phosphate

A) is produced by the process of anaerobic respiration.

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

C) acts as an energy reserve in muscle tissue.

D) is only formed during strenuous exercise.

E) cannot transfer its phosphate group to ADP.

30) During anaerobic glycolysis,

A) ATP is produced.

B) pyruvic acid is produced.

C) oxygen is not consumed.

D) carbohydrate is metabolized.

E) All of the answers are correct.

31) Which of the following would not lead to increased oxygen consumption?

A) increased heat production

B) increased conversion of lactic acid to glucose

C) increased anaerobic respiration by muscle cells

D) increased muscle activity

E) All of the answers are correct; none would lead to increased oxygen consumption.

32) Because skeletal muscle contractions demand large quantities of ATP, skeletal muscles have

A) a rich nerve supply to ensure a rapid succession of action potentials.

B) massive creatine phosphate reserves for long periods of sustained contractions.

C) extra calcium reserves which can serve as fuel molecules during ATP synthesis.

D) adipose tissue between fibers to supply nutrients for ATP production.

E) many mitochondria and a rich blood supply.

33) Decreased blood flow to a muscle could result in all of the following except

A) muscle fatigue.

B) an oxygen debt.

C) an increase in intracellular glycogen.

D) a shift to anaerobic glycolysis.

E) an increase in intracellular lactic acid.

Figure 12-1 The