Chapter 6 Muscular System Lecture Exam

The number of muscle fibers in an individual motor unit is 1. high where precise control is needed. 2. low where precise control is needed. 3. low in muscles for posture. 4. high in muscles moving the eyeballs.

2 only

During muscle contraction, the energy in creatine phosphate is used to convert

ADP to ATP.

The immediate direct source of energy for muscle contraction is

ATP

All of the following are events that occur in skeletal muscle fibers EXCEPT: tetanus. twitch contractions. rigor mortis. wave summation. All of these answer choices are correct.

All of these answer choices are correct.

Muscle fatigue can be caused by

All of these choices.

Name the skeletal muscle structure indicated.

Emimysium (Outer of muscle)

A twitch contraction involves a brief contraction of all the muscle fibers found in a single skeletal muscle.

False

Antagonists are the prime movers of bones during a movement, while synergists oppose the desired movement.

False

Both smooth and cardiac muscles are involuntary and contain actin and myosin filaments. However, the actin and myosin filaments in the smooth muscle are arranged in sarcomeres (similar to skeletal muscle), while in cardiac muscle the filaments are arranged irregularly throughout the cytoplasm.

False

Calcium binds to a protein found in the thick myofilaments to start the muscle contraction process.

False

Each skeletal muscle fiber is directly controlled by two or more motor neurons.

False

Muscles should be kept tightly contracted while stretching.

False

Skeletal muscles are not very well supplied with nerves and blood vessels.

False

Slow oxidative skeletal muscle fibers fatigue easily.

False

Smooth muscle is under voluntary control.

False

The H zone is located in the center of the I band.

False

The ends of axon terminals enlarge into swellings called motor end plates.

False

The muscle attachment to the bone that moves the most during a contraction is called the origin.

False

The myofibrils of skeletal muscle fibers are composed of three types of myofilaments.

False

The tibialis anterior is found on the back of the shin.

False

A flaccid muscle would indicate damage to the nerve serving that muscle.

True

A skeletal muscle must be stimulated by a motor neuron in order to contract.

True

An individual skeletal muscle is made of bundles of fascicles composed of bundles of muscle fibers consisting of bundles of myofibrils made up of numerous myofilaments.

True

During muscle contraction, the myosin heads pull on the actin, causing the thin filaments to slide toward the center of the sarcomere.

True

During muscle contraction, the power stroke causes the thin filaments to slide further between the thick filaments.

True

Muscle tissue plays a major role in maintenance of homeostasis.

True

The detachment of myosin heads from actin requires ATP.

True

There are two types of smooth muscle tissue, visceral and multiunit.

True

Unfused (incomplete) tetanus involves the process of wave summation

True

The neurotransmitter at the neuromuscular junction is

acetylcholine.

Acetylcholine that has been released into the synaptic cleft is rapidly inactivated by

acetylcholinesterase.

Thin myofilaments are composed of

actin, troponin, and tropomyosin

Muscle tone results from

activation of a small number of motor units.

During oxygen debt, some of the lactic acid produced by anaerobic respiration in muscle fibers is converted into glycogen in the

liver.

Which of the following substances is released from the sarcoplasmic reticulum to initiate muscle contraction?

calcium

Which of the following is/are striated and involuntary?

cardiac muscle

Which of the following is a muscle that moves the mandible?

masseter

A motor unit is all the muscle fascicles found in a single muscle. muscle fibers controlled by a single motor neuron. myofibrils in a single muscle fiber. muscles involved in a single movement. None of these choices.

muscle fibers controlled by a single motor neuron.

Which of the following is a muscle involved in facial expressions? external oblique rhomboideus teres major platysma pronator teres

platysma

All of the following are muscles that move the humerus EXCEPT: latissimus dorsi. infraspinatus. teres major. deltoid. pronator teres.

pronator teres.

The plasma membrane of a skeletal muscle cell is called the

sarcolemma.

The organelle storing calcium in resting skeletal muscle fibers is the

sarcoplasmic reticulum.

Intermediate filaments are structures of

smooth muscle.

A muscle that decreases the size of an opening is a

sphincter.

Tissues, like muscles, stretch best when

stretched slow and warmed up

Cardiac muscle is

striated, single nucleated and involuntary

The space between an axon terminal and the sarcolemma is the

synaptic cleft.

A sustained contraction of a muscle is called

tetanus.

Which of the following is NOT a characteristic used to name skeletal muscles? direction of fibers thickness of fibers location size number of origins

thickness of fibers

Which of the following is a muscle that moves the foot? tibialis anterior semitendinosus sartorius biceps femoris gracilis

tibialis anterior

Tunnel-like extensions of the sarcolemma into the muscle fiber are

transverse tubules.

Which of the following is a muscle whose insertion is found on the pectoral girdle? trapezius pectoralis major latissimus dorsi gracilis sartorius

trapezius

A muscle that has three origins is called a

tricep

Skeletal muscle tissue is striated and voluntary.

true

The infraspinatus muscle is a muscle that moves the upper leg. lower leg. upper arm. lower arm. carpals.

upper arm.

Which of the following is NOT a function of muscle tissue? heat production control the volume of a hollow organ vitamin D production body movements body position

vitamin D production

Intercalated discs are characteristic structures found in

cardiac muscle.

All of the following are muscles of the lower limb EXCEPT the deltoid. adductor magnus. adductor longus. quadriceps femoris. vastus medialis.

deltoid.

All of the following are proteins of myofilaments EXCEPT

elastin.

Each individual muscle fiber is covered by connective tissue called the

endomysium

Which of the following flexes and abducts the wrist? flexor digitorum profundus flexor digitorum superficialis flexor carpi radialis flexor carpi ulnaris palmaris longus

flexor carpi radialis

Which of the following muscles adducts the thigh and flexes the leg? rectus femoris gracilis tibialis anterior gastrocnemius flexor digitorum longus

gracilis

Based on its name, which of the following best describes characteristics of the biceps femoris muscle?

has two origins and found in the upper leg

All of the following are muscles that move the eyeball EXCEPT superior rectus. lateral rectus. inferior oblique. internal oblique. superior oblique.

internal oblique.

A muscle that produces an upward movement is a

levator.

The difference between picking up a pencil versus picking up a 30 pound weight is 1. the number of antagonists involved. 2. the size of the motor units involved. 3. the use of glycogen as a primary energy source. 4. the number of motor units involved.

2 and 4

The darker portion of the sarcomere composed of thick filaments and in some areas overlapping thin filaments is the

A band.

Which of the following is NOT a characteristic of fast glycolytic (FG) skeletal muscle fibers? A. fatigue rapidly B. most powerful and rapid contractions C. high concentration of myoglobin D. low number of mitochondria E. large amounts of stored glycogen

C. high concentration of myoglobin

Which is true of smooth muscle? It is not under voluntary control. It contracts faster than skeletal muscle. It fatigues faster than skeletal muscle. Each muscle fiber must be innervated. All of these choices.

It is not under voluntary control.

Which of the following events occur during the latent period of a twitch contraction in a skeletal muscle?

The muscle action potential spreads over the sarcolemma.

The sarcomere is the area between two

Z discs.

The muscle that produces the action of sucking is the

buccinator.

Which of the following muscles is not part of the quadriceps femoris? a. rectus femoris b. biceps femoris c. vastus medialis d. vastus lateralis e. vastus intermedius

b. biceps femoris

An increase in the diameter of muscle fibers is called

muscular hypertrophy.

The pigmented protein in the muscle fibers that stores oxygen is

myoglobin

Smooth muscle is

non-striated, single nucleated and involuntary.

The point of attachment of a muscle (by means of a tendon) to the stationary bone is called the

origin.

After a period of maximal muscle activity, lactic acid must be converted to glycogen. This is a result of

oxygen debt.

The connective tissue that covers muscle fascicles and holds them together is called the

perimysium