Chapter 7 Pretest (Muscular System)

Chapter 7 – Pretest (muscular system)

1.The major functions of the muscular system include all of the following EXCEPT:
A.body movement
B.prevention of water loss
C.maintenance of posture
D.respiration
E.temperature homeostasis

2.Contractibility is the ability of skeletal muscle to
A.shorten with force.
B.lengthen passively.
C.respond to a stimulus.
D.recoil to their original resting length.
E.be stretched.

3.Connective tissue that surrounds the fasciculi is called
A.perimysium.
B.endomysium.
C.fascia.
D.fasciculi.
E.microfibrils.

4.Muscle myofibrils
A.contain actin and myosin myofilaments.
B.extend from one end of the muscle fiber to the other.
C.contain sarcomeres joined end to end.
D.have all of these properties.
E.contain actin and myosin myofilaments and extend from one end of the muscle fiber to the other.

5.The ______is the functional unit of skeletal muscle because it is the smallest portion of the skeletal muscle capable of ______.
A.muscle fiber, receiving a stimulus
B.muscle fiber, contracting
C.sarcomere, contracting
D.sarcomere, receiving a stimulus
E.myofibril, contracting

6.Actin myofilaments
A.resemble bundles of minute golf clubs.
B.are attached to Z lines at one end.
C.form the I band where actin overlaps with myosin myofilaments.
D.form the epimysium.
E.have all of these characteristics.

7.The resting membrane potential
A.occurs when the outside of the cell membrane is negatively charged.
B.is reversed in sign when sodium ions rush out of the cell.
C.will be changed if the membrane permeability to one or more ions is selectively altered.
D.is reestablished by depolarization after an action potential.
E.only occurs when the cytosol has a net negative charge.

8.Which of the following statements is FALSE?
A.The resting potential of a cell develops because the cell membrane is more permeable to K+ than it is to most other ions.
B.The concentration of Na+ is higher inside the cell than outside.
C.Potassium ions only diffuse down their gradient until the charge difference across the membrane is great enough (electrical equilibrium) to prevent additional diffusion.
D.Potassium's tendency to diffuse out is opposed by the attractive forces of the negative charge inside the cell.
E.The sodium-potassium exchange pump maintains the normal resting concentrations of ions on either side of the cell membrane.

9.What would happen if the cell membrane suddenly became impermeable to K+ ions?
A.The outside of the cell membrane would become more positively charged.
B.The cell would become more negatively charged.
C.The cell would become more positively charged.
D.The cell would depolarize.
E.The outside of the cell membrane would become more positively charged and the cell would depolarize are correct.

10.Acetylcholine
A.is the neurotransmitter at the neuromuscular junction.
B.is broken down by acetylcholinesterase.
C.binds to receptors on the muscle cell membrane.
D.causes an influx of sodium ions into the muscle cell when bound to its receptor.
E.has all of these characteristics.

11.A single motor neuron and all the skeletal muscle fibers it innervates is called a
A.neuromuscular junction.
B.synaptic cleft.
C.motor unit.
D.synapse.
E.presynaptic terminal.

12.Given these events:
1) calcium ions move along their concentration gradient
2) action potential in cell membrane
3) opening of ion channels in sarcoplasmic reticulum
4) action potential in T tubules
5) actin to myosin cross-bridges form
Arrange them in the correct sequence as they participate during skeletal muscle contraction.
A.1, 2, 5, 3, 4
B.1, 5, 4, 3, 2
C.2, 4, 3, 1, 5
D.2, 1, 5, 3, 4
E.5, 3, 4, 2, 1

13.What ensures that one action potential in the neuron yields only one action potential in the skeletal muscle fibers of the stimulated motor unit and therefore only one contraction per fiber?
A.the amount of calcium that enters the pre-synaptic cell
B.the rate of diffusion of acetylcholine across the synaptic cleft
C.the number of muscle fibers that make up the motor unit
D.enzymatic breakdown of acetylcholine by acetylcholinesterase
E.All of these ensure this one to one ratio.

14.Put the following events in chronological order. (Some of the steps may be missing.)
1) Ca++ floods into the pre-synaptic neuron.
2) Ach (Acetylcholine) binds to ACh receptors in the sarcolemma.
3) Na+ floods into the post-synaptic muscle cell.
4) The A.P arrives at the pre-synaptic terminal causing Ca++ channels to open.
5) Ach from the synaptic vesicles spills into the pre-synaptic cleft.
6) A post-synaptic action potential results in the muscle fiber (depolarization).
A.4, 1, 5, 2, 3, 6
B.4, 1, 2, 5, 3, 6
C.3, 6, 5, 4, 1, 2
D.2, 1, 6, 3, 4, 5
E.6, 3, 2, 5, 1, 4

15.Curare is a poison used by South American Indians. It is known to bind to ACh receptors preventing the binding of ACh. What effect would it have on muscle function?
A.The muscle fibers would contract uncontrollably and continually.
B.The muscle fibers would not contract because the Na+ channels which cause depolarization of the muscle fiber membrane are never signaled to open.
C.The pre-synaptic release of ACh would be inhibited, therefore the muscle would not contract.
D.The action of acetylcholinesterase would be inhibited causing increased contraction.
E.Both the muscle fibers would contract uncontrollably and continually and the action of acetylcholinesterase would be inhibited causing increased contraction would occur.

16.ATP
A.attaches to the myosin myofilaments.
B.provides energy for the movement of the cross bridges.
C.is required for muscle relaxation.
D.releases part of its energy as heat.
E.has all of these characteristics.

17.The condition in which a muscle remains contracted between stimuli without relaxing is called
A.recruitment.
B.tetanus.
C.the all-or-none response.
D.a motor unit.
E.the lag phase.

18.Anaerobic respiration
A.is used by all cells during sustained periods of exercise.
B.produces the most ATP's for each glucose molecule broken down.
C.produces lactic acid within the muscle.
D.produces an oxygen debt.
E.produces lactic acid within the muscle and produces an oxygen debt.

19.What is the function of tropomyosin in muscle contraction?
A.to bind to the myosin head and cock it back
B.to prevent the inappropriate binding of actin to myosin (inhibition)
C.to initiate contraction by releasing Ca++
D.to move the troponin complex off the active site of myosin
E.to form the crossbridge

20.Slow-twitch muscle fibers
A.are the predominant type of muscle fibers in the upper limbs.
B.have a richer blood supply than fast twitch fibers, and contain myoglobin.
C.would be used for activities resulting in (or requiring) anaerobic respiration.
D.fatigue more easily than fast-twitch fibers.
E.have all of these characteristics.

21.Which of the following characteristics would establish conclusively that muscle tissue being examined was skeletal muscle tissue?
A.several nuclei per cell
B.striations present
C.contracts spontaneously
D.intercalated disks present
E.under involuntary control

22.If someone winks at you, they are using their
A.zygomaticus muscles.
B.occipitofrontalis muscle.
C.orbicularis oculi.
D.depressor anguli oris.
E.orbicularis oris.

23.The biceps brachii muscle and the triceps brachii muscle
A.are synergists.
B.are antagonists.
C.both flex the forearm.
D.are both antagonists and flexors of the forearm.
E.are both synergists and flexors of the forearm.

24.An anterior thigh muscle that extends the leg is the
A.sartorius.
B.quadriceps femoris.
C.hamstring group.
D.adductor group.
E.iliopsoas.

25.A superficial muscle of the posterior compartment of the leg is the
A.tibialis anterior.
B.peroneus.
C.gastrocnemius.
D.plantar fascia.
E.hanstring group.

26.The ______is a group of muscle cells surrounded by perimysium.
A.myofilament
B.myofibril
C.muscle fiber
D.muscle fasciculus
E.whole skeletal muscle

27.A ______is a single muscle cell.
A.myofilament
B.myofibril
C.muscle fiber
D.muscle fasciculus
E.whole skeletal muscle

28.Muscles are named according to their
A.location or number of heads.
B.function or action.
C.origin or insertion point.
D.size or shape.
E.Muscles can be named based on all of the above features.

29.The ______is the smooth ER of a muscle fiber and stores calcium ions.
A.sarcolemma
B.sarcoplasmic reticulum
C.sarcomere
D.sarcoplasm
E.T tubules

30.In ______contraction the amount of tension increases during contraction, but the length of the muscle does not change.
A.concentric
B.eccentric
C.isotonic
D.isometric