Muscular System review

5) What creates the alternating light and dark bands that provides the striation pattern on skeletal muscle tissue? A) sarcoplasm and sarcolemma B) thick filaments and myosin heads C) A bands and I bands D) H zones and M lines E) Z discs and H zones

C) A bands and I bands

5) The epimysium is represented by ________. A) Label A B) Label B C) Label C D) Label D

A) Label A

22) The arrangement of fascicles in orbicularis oris is ________. A) circular B) convergent C) pennate D) fusiform

A) circular

18) A smooth, sustained contraction, with no evidence of relaxation, is called ________. A) fused, or complete, tetanus B) a twitch C) unfused, or incomplete, tetanus D) summing of contractions

A) fused, or complete, tetanus

20) Skeletal muscle, as a whole, can generate different amounts of force, and different degrees of shortening, in response to stimuli. What is this concept called? A) graded response B) twitch C) fused, or complete, tetanus D) incomplete, or unfused, tetanus E) action potential

A) graded response

21) Type of movement that turns the sole of the foot medially A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

A) inversion

5) Discuss the role of the myosin heads in sliding filament theory.

The myosin heads attach to binding sites on the actin filaments to form cross bridges and to begin the process of sliding. The myosin heads swivel toward the center of the sarcomere, attaching and detaching several times which generates tension that helps pull the thin filaments toward the center of the sarcomere. This "walking" of the myosin heads along the thin filaments allows the thin filaments to slide past the thick filaments. As a result, the Z discs are pulled closer together. Since this event occurs simultaneously in sarcomeres throughout the cell, the muscle cell shortens.

8) Explain how isometric and isotonic contractions differ, using examples of each.

1. Isometric contractions are contractions in which the muscles do not shorten. The myofilaments are trying to slide, but the muscle is pitted against some more or less immovable object. For example, when you push the palms of your hands together in front of you, your arm and chest muscles are contracting isometrically. 2. Isotonic contractions occur due to the successful sliding of the myofilaments. The muscle shortens and movement occurs. Bending the knee, lifting weights, and smiling are all examples of isotonic contractions.

23) Primary action of the adductor muscles A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

F) adduction

18) Type of movement that points the toes A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

G) plantar flexion

Explain what meaning is inferred in the muscle name rectus femoris.

The term, rectus, means straight. The fibers in this muscle run straight along a plane. The reference to the femur bone is relayed in femoris. Together, these terms tell us the muscle fibers of rectus femoris travel "straight along the femur bone."

2) The A band within a myofibril is indicated by ________. A) Label A B) Label B C) Label C D) Label D

A) Label A

16) According to the sliding filament theory, how does muscle contraction occur? A) Myosin heads form cross bridges and pull thin filaments, causing them to slide. B) Both thick and thin filaments shorten as the muscle contracts. C) A bands bunch up and shorten as myosin heads attach to thin filaments. D) Myosin heads attach and detach from thin filaments, causing thin filaments to shorten.

A) Myosin heads form cross bridges and pull thin filaments, causing them to slide.

19) Contractions in which muscles shorten and produce movement are known as ________. A) isotonic contractions B) twitches C) isometric contractions D) resistance exercises

A) isotonic contractions

33) Which of these muscles is located on the ventral (anterior) side of the body? A) pectoralis major B) occipitalis C) gastrocnemius D) gluteus medius E) latissimus dorsi

A) pectoralis major

4) The plasma membrane of a skeletal muscle cell is called the ________. A) sarcolemma B) sarcomere C) myofilament D) sarcoplasm E) sarcoplasmic reticulum

A) sarcolemma

6) Which type of muscle tissue contracts most quickly upon stimulation? A) skeletal B) visceral C) cardiac D) smooth E) tendons

A) skeletal

9) Which one of the following is composed mostly of the protein myosin? A) thick filaments B) thin filaments C) all myofilaments D) Z discs E) light bands

A) thick filaments

2) Describe the events that occur from the time that a motor neuron releases acetylcholine at the neuromuscular junction until muscle cell contraction occurs.

Acetylcholine (ACh) is released from the axon terminals of a motor neuron, which diffuses across the synaptic cleft and attaches to receptors in the sarcolemma. ACh binds and opens channels that allow the simultaneous passage of sodium ions into the muscle fiber and potassium ions out of the muscle fiber. Since more sodium ions enter the muscle fiber than potassium ions leave, a local area of depolarization develops. As more channels that only allow sodium entry open, an action potential is initiated and sweeps over the entire sarcolemma. Calcium ions are released from storage areas inside the sarcoplasmic reticulum of the muscle cell. They attach to the myofilaments, which triggers the sliding of the myofilaments and causes a muscle cell contraction.

21) Which of these events must occur first to trigger the skeletal muscle to generate an action potential and contract? A) Sodium ions rush into the cell. B) Acetylcholine (ACh) binds to receptors on the sarcolemma and allows passage of sodium ions into the cell. C) Potassium ions diffuse out of the muscle cell. D) The sodium-potassium pump restores sodium and potassium back to their initial positions. E) Acetylcholinesterase (AchE) breaks down acetylcholine (ACh).

B) Acetylcholine (ACh) binds to receptors on the sarcolemma and allows passage of sodium ions into the cell.

18) During skeletal muscle contraction, to what do myosin heads bind? A) myosin filaments B) actin filaments C) Z discs D) thick filaments E) the H zone

B) actin filaments

15) What is the unstoppable electrical current that travels down the length of the entire surface of a sarcolemma? A) neuromuscular junction B) action potential C) neurotransmitter D) acetylcholine

B) action potential

15) Type of movement that decreases the angle of the joint A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

B) flexion

25) Primary action of the rectus abdominis A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

B) flexion

36) Which muscle forms the curved calf of the posterior leg? A) fibularis longus B) gastrocnemius C) rectus femoris D) tibialis anterior E) soleus

B) gastrocnemius

13) One neuron and all the skeletal muscles it stimulates is known as a ________. A) sarcoplasmic reticulum B) motor unit C) synaptic cleft D) neuromuscular junction

B) motor unit

26) An inherited disease that causes muscles to degenerate and atrophy is known as ________. A) torticollis B) muscular dystrophy C) cystic fibrosis D) myasthenia gravis

B) muscular dystrophy

25) Which of the following is an example of an isometric contraction? A) shaking the head as to say "no" B) pushing against an immovable wall C) bending the elbow D) rotating the arm E) nodding the head as to say "yes"

B) pushing against an immovable wall

8) A sarcomere is ________. A) the nonfunctional unit of skeletal muscle B) the contractile unit between two Z discs C) the area between two intercalated discs D) the wavy lines on the cell, as seen in a microscope E) a compartment in a myofilament

B) the contractile unit between two Z discs

6) Fascicle arrangements produce skeletal muscles with different structures and functional properties, and determine their individual range of motion and power. List the seven different fascicle arrangements of human skeletal muscles and give a specific example of each.

1. Circular—orbicularis oris, orbicularis oculi 2. Convergent—pectoralis major 3. Parallel—sartorius 4. Unipennate—extensor digitorum longus 5. Multipennate—deltoid 6. Fusiform—biceps brachii 7. Bipennate—rectus femoris

1) The I band within a skeletal muscle fiber is indicated by ________. A) Label A B) Label B C) Label C D) Label D

B) Label B

8) The endomysium that wraps individual muscle fibers is indicated by ________. A) Label A B) Label B C) Label C D) Label D

B) Label B

4) The myofilament composed of actin is indicated by ________. A) Label A B) Label B C) Label C D) Label D

C) Label C

6) The perimysium wraps a fascicle of muscle cells and is represented by ________. A) Label A B) Label B C) Label C D) Label D

C) Label C

13) The mechanical force of contraction is generated by ________. A) shortening of the thick filaments B) shortening of the thin filaments C) a sliding of thin filaments past thick filaments D) the "accordion-like" folding of thin and thick filaments E) the temporary disappearance of thin filaments

C) a sliding of thin filaments past thick filaments

2) What is covered by the endomysium? A) fascicles of muscle cells B) an entire muscle C) an individual muscle cell D) myofibrils E) smooth muscle only

C) an individual muscle cell

21) Muscles that perform opposite actions to one another are termed ________. A) synergists B) prime movers C) antagonists D) fixators

C) antagonists

44) What condition results if muscles are not used, such as when immobilized in a cast for healing a broken bone? A) hypertrophy B) lordosis C) atrophy D) spina bifida E) scoliosis

C) atrophy

12) Muscle tissue has the ability to shorten when adequately stimulated, a characteristic known as ________. A) elasticity B) irritability C) contractility D) extensibility

C) contractility

11) A motor neuron and all of the skeletal muscle fibers it stimulates are termed a ________. A) myofilament B) synaptic cleft C) motor unit D) neuromuscular junction E) neurotransmitter

C) motor unit

3) The H zone, located within the A band, lacks thin filaments and is represented by ________. A) Label A B) Label B C) Label C D) Label D

D) Label D

7) The muscle fiber (cell) is indicated by ________. A) Label A B) Label B C) Label C D) Label D

D) Label D

10) What is released by axon terminals into the synaptic cleft to stimulate a muscle to contract? A) potassium ions B) actin C) sodium ions D) acetylcholine E) myosin heads

D) acetylcholine

28) Which movement is opposite to abduction? A) flexion B) rotation C) circumduction D) adduction E) supination

D) adduction

16) Neurotransmitters are released upon stimulation from a nerve impulse from the ________. A) myofibrils B) sarcoplasmic reticulum C) thick filaments D) axon terminals of the motor neuron E) sarcolemma of the muscle cell

D) axon terminals of the motor neuron

40) Which of the following consists of two large, flat muscles that cover the lower back? A) deltoid B) biceps brachii C) triceps brachii D) latissimus dorsi E) pectoralis major

D) latissimus dorsi

27) Which of the following is a type isometric exercise in which muscles increase in size and strength? A) swimming B) biking C) jogging D) lifting weights E) dancing

D) lifting weights

45) Which one of the following is NOT a criterion generally used in naming muscles? A) relative size of the muscle B) number of origins of the muscle C) shape of the muscle D) method of attachment of the muscle to bone E) action of the muscle

D) method of attachment of the muscle to bone

20) The point of muscle attachment to an immovable or less movable bone is known as the ________. A) innervation B) action C) insertion D) origin

D) origin

17) What must rush into a muscle cell to promote its depolarization? A) potassium ions B) calcium ions C) acetylcholine D) sodium ions E) acetylcholinesterase

D) sodium ions

16) Type of movement that allows you to carry a soup bowl A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

D) supination

15) The gap between the axon terminal of a motor neuron and the sarcolemma of a skeletal muscle cell is called the ________. A) motor unit B) sarcomere C) neuromuscular junction D) synaptic cleft E) cross bridge

D) synaptic cleft

14) What is acetylcholine? A) an ion pump on the postsynaptic membrane B) a source of energy for muscle contraction C) a component of thick myofilaments D) an oxygen-binding protein E) a neurotransmitter that stimulates skeletal muscle to contract

E) a neurotransmitter that stimulates skeletal muscle to contract

20) The movement of a limb away from the body midline A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

E) abduction

22) Primary action of the deltoid A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

E) abduction

19) What enzyme breaks down acetylcholine into acetic acid and choline to prevent continued contraction of the muscle fiber? A) potassium ions B) cross bridges C) calcium ions D) sarcoplasmic reticulum E) acetylcholinesterase

E) acetylcholinesterase

7) Which of the following is NOT a function of the muscular system? A) production of movement B) maintenance of posture C) stabilization of joints D) generation of heat E) blood cell formation

E) blood cell formation

17) The movement of a limb toward the body midline A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

F) adduction

12) Why are calcium ions necessary for skeletal muscle contraction? A) Calcium ions increase the speed of the action potential transmitted along the sarcolemma. B) Calcium ions release the inhibition on Z discs. C) Calcium ions trigger the binding of myosin heads to actin filaments. D) Calcium ions cause ATP binding to actin. E) Calcium ions bind to regulatory proteins on the myosin filaments, changing both their shape and their position on the thick filaments.

C) Calcium ions trigger the binding of myosin heads to actin filaments.

14) The heads of the myosin myofilaments are called ________ when they link the thick and thin filaments together during skeletal muscle contraction. A) neuromuscular junctions B) synapses C) cross bridges D) motor units

C) cross bridges

19) The movement of a bone around its longitudinal axis A) inversion B) flexion C) rotation D) supination E) abduction F) adduction G) plantar flexion H) extension

C) rotation

7) Discuss the importance of calcium ions in skeletal muscle contraction.

Calcium ions are necessary for myosin heads to attach to binding sites on actin filaments. As the action potential travels into the muscle cell, it stimulates the sarcoplasmic reticulum surrounding each myofibril to release its stored calcium ions into the sarcoplasm. The calcium ions trigger the binding of myosin heads to actin filaments and the initiation of the sliding of filaments.

22) A skeletal muscle twitch differs from a tetanic contraction in that ________. A) the tetanic contraction is considered abnormal, while the twitch is a normal muscle response B) the tetanic contraction is caused by a single stimulus, while the twitch is caused by very rapid multiple stimuli C) the muscle twitch is prolonged and continuous while a tetanic contraction is brief and "jerky" D) the muscle twitch occurs only in small muscles while a tetanic contraction occurs in large muscle groups E) the muscle twitch is a brief and "jerky" movement, while the tetanic contraction is prolonged and continuous

E) the muscle twitch is a brief and "jerky" movement, while the tetanic contraction is prolonged and continuous