Chapter 7

Myofibrils are made primarily of troponin. tropomyosin. epimysium. ATP and ADP. actin and myosin

actin and myosin

The term used to describe muscular growth in response to usage is muscular dystrophy. multiple sclerosis. hypertrophy. myopathy. atrophy.

hypertrophy

Neurotransmitters that cause skeletal muscle contraction are normally stored in actin. motor neuron axon terminals. motor units. motor end plates. myofibrils.

motor neuron axon terminals

The skeletal muscles store calcium ions in the terminal cisternae of the sarcosome. sarcomere. sarcoplasmic reticulum. sarcoplasm. sarcolemma.

sarcoplasmic reticulum

A person whose genetic makeup makes him or her a better marathon runner than a sprinter probably has more ________ in his or her leg muscles. red fibers intermediate fibers dark fibers fast fibers slow fibers

slow fibers

The muscle that produces the action of standing on tip-toes is the extensor digitorum. peroneus. soleus. tibialis anterior. plantaris.

soleus.

Creatine phosphate serves to supply energy to synthesize ATP. decompose ADP. cause the decomposition of ATP. synthesize glucose. synthesize ADP.

supply energy to synthesize ATP

Acetylcholinesterase is found within the nucleus. myofibril. sarcomere. synaptic cleft. sarcolemma.

synaptic cleft

Which statement regarding isometric contractions is true? Examples are walking and running. Tension rises during a contraction. The tension produced never exceeds the load. Tension remains at a constant level until relaxation occurs. The skeletal muscle's length changes.

The tension produced never exceeds the load

Upon the nerve impulse arriving at the axon terminal, active sites on actin are exposed. acetylcholine is released. actin heads will bind to myosin. muscle relaxation occurs. active sites on myosin are expose

acetylcholine is released

The striated appearance of skeletal muscle results from actin and myosin arrangement. the sarcoplasmic reticulum. cisternae placement. the transverse tubule pattern. the perimysium arrangement.

actin and myosin arrangement

Which of the following terms is a descriptive word for a muscle's action? biceps costalis obliques pectinate adductor

adductor

A resting muscle generates most of its ATP by conversion of creatine phosphate. aerobic respiration. anaerobic respiration. heat loss. glycolysis.

aerobic respiration

The specialized sarcolemma that contains acetylcholine receptors is the motor unit. I band. motor end plate. synaptic cleft. synaptic knob.

motor end plate

For cross bridge release, it is necessary for __________ to attach to the myosin head. A) a tropomyosin molecule B) ATP C) Ca'2 + ions D) a troponin molecule E) the sarcolemma

B) ATP

Which of these is NOT a part of the actin myofilament? A) actin B) cisternae C) tropomyosin D) troponin

B) cisternae

During contraction, muscles shorten ______________, and then lengthen ______________. A) forcefully, forcefully B) forcefully, passively C) passively, forcefully D) passively, passively

B) forcefully, passively

Which of these locations has the ability to break down ATP, which releases energy? A) globular actin molecule B) head of myosin molecule C) troponin molecule D) tropomyosin molecule E) troponin- tropomyosin complex

B) head of myosin molecule

Anaerobic respiration A) produces 38 ATPs per glucose molecule B) produces an oxygen debt C) occurs in resting muscles or muscles undergoing long-term exercise D) all of these

B) produces an oxygen debt

Smooth muscle cells have to be innervated by motor neurons. are larger than cardiac muscle cells. contain intercalated discs. are multinucleate. are spindle-shaped.

are spindle-shaped

Which of the following occurs when tension production rises to a peak and very brief periods of relaxation occur? latency complete tetanus incomplete tetanus tension plateau resting period

incomplete tetanus

Tropomyosin strands are held in position by which of the following? actin molecules ATP molecules myosin molecules troponin molecules calcium ions

troponin molecules

A muscle contraction in which the muscle produces an increasing tension, but the length remains constant is a(n) A) isometric contraction B) isotonic contraction C) concentric contraction D) eccentric contraction

A) isometric contraction

Nonstriated, involuntary muscle is white skeletal. intermediate skeletal. cardiac. red skeletal. smooth.

smooth

Which muscle extends the elbow during the action of push-ups? trapezius triceps brachii brachialis deltoid biceps brachii

triceps brachii

A single stimulus-contraction-relaxation sequence in a muscle fiber is known as a(n) summation. complete tetanus. latent period. twitch. incomplete tetanus.

twitch

A layer of collagen fibers that surrounds an entire muscle is called epimysium. perimysium. endomysium. sarcomere. sarcolemma.

epimysium

Each myofibril consists of approximately ________ sarcomeres. 100,000 10 500 10,000 2-3 million

10,000

Given these events: 1. The passage of an action potential along a T tubule triggers the release of calcium ions from the sarcoplasmic reticulum 2. When an action potential arrives at the axon terminal, acetylcholine (Ach) is released into the synaptic cleft 3. The binding of ACh to receptors on the motor end plate leads to the generation of an action potential in the sarcolemma 4. Calcium binds to troponin What is the correct arrangement for neuromuscular junction to trigger a contraction.

2, 3, 1, 4

Place these steps of muscle contraction in the correct order. 1. Action potential is generated along the sarcolemma 2. Nerve impulse arrives at synapse 3. Calcium is released into muscle cell cytoplasm 4. Acetylcholine is produced 5. Actin and myosin molecules continuously cross-link, with actin molecules being pulled inward 2, 3, 4, 1, 5 1, 2, 4, 3, 5 4, 2, 1, 5, 3 2, 4, 1, 3, 5 1, 2, 4, 5, 3

2, 4, 1, 3, 5

Identify the CORRECT sequence of steps in the muscle contraction cycle 1. ATP binds to the myosin head, breaking the link to actin 2. Myosin heads pivot toward the M- line 3. Calcium ions bind to troponin, exposing the active sites 4. Myosin heads bind to the active sites, forming cross-bridges

3, 4, 2, 1

Which of these units contains overlapping actin and myosin myofilaments? A) A band B) H zone C) I band D) M line E) Z line

A) A band

Muscle cells that are cylindrical and branched, each with a single, centrally located nucleus, and that contract spontaneously are A) cardiac muscle B) skeletal muscle C) smooth muscle D) unknown: not enough characteristics to determine the type of muscle

A) cardiac muscle

Which of the following is one of the steps that ends a contraction? Acetylcholine binds to receptors on the sarcolemma. Calcium ions bind to troponin. Acetylcholine is broken down by acetylcholinesterase. An action potential spreads across the entire surface of the muscle fiber. Sarcoplasmic reticulum absorbs sodium ions.

Acetylcholine is broken down by acetylcholinesterase

Even though each muscle fiber responds in all-or-none fashion, a whole muscle can contract with varying force because of A) different threshold values of each fiber B) total tetanus of the muscle C) multiple motor unit recruitment D) rigor mortis E) the lag phase of contraction

C) multiple motor unit recruitment

During moderate activity, which of the following is true regarding muscle metabolism? The ATP produced is used to build energy reserves of ATP and glycogen. Mitochondria are not involved. Mitochondrial activity provides about one-third of the ATP consumed. Most ATP is produced through glycolysis, with lactate and hydrogen ions as byproducts. Glucose and fatty acids are catabolized.

Glucose and fatty acids are catabolized

The area of the sarcomere that is the light region between two successive A-bands is the M line. myofibril. H band. Z line. I band.

I band

The area of the sarcomere that is the light region between two successive A-bands is the myofibril. H band. M line. I band. Z line.

I band

Which statement regarding "heat loss" is true? Heat loss is reduced when blood flow to the skin increases. Muscle activity does not generate heat. Shivering in a cold environment results in higher levels of heat loss. Muscle contractions play an important role in the maintenance of normal body temperature. When skeletal muscles are contracting at peak levels, body temperature drops.

Muscle contractions play an important role in the maintenance of normal body temperature

Which of the following statements describes how muscles help maintain homeostasis? Skeletal muscle contractions help maintain body temperature. Skeletal muscles are responsible for the pumping action of the heart. Skeletal muscles are responsible for guarding the openings of the digestive and urinary tracts. Skeletal muscles support the weight of some internal organs. The contractions of skeletal muscles pull on tendons and move elements of the skeleton.

Skeletal muscle contractions help maintain body temperature

Which of the following acts to flex the elbow? brachioradialis supinator palmaris longus triceps brachii pronator quadratus

brachioradialis

In response to action potentials arriving from the transverse tubules, the sarcoplasmic reticulum releases sodium ions. calcium ions. acetylcholine. potassium ions. acetylcholinesterase.

calcium ions

Muscle cells actively lengthen. possess a mechanism that regulates the tension amount by changing the number of contracting sarcomeres. generate compression. vary tension production based on the amount of sodium ions bound to actin. can only contract.

can only contract

"Anaerobic endurance" is determined by the availability of carbohydrates, lipids, or amino acids for breakdown. does not promote muscle hypertrophy. is exemplified by contractions of fast muscle fibers. is used during long, slow athletic activities. is the length of time a muscle can continue to contract while supported by mitochondrial activities.

is exemplified by contractions of fast muscle fibers

Calcium ions are released from the sarcoplasmic reticulum during the ________ phase of contraction. contraction twitch relaxation recovery latent

latent

Regarding lactic acid regulation, which cells in the body consume extra oxygen and produce ATP for the conversion of excess lactate absorbed from the blood back to glucose? skeletal muscle fibers neurons erythrocytes liver cells cardiac muscle cells

liver cells

During activities requiring aerobic endurance, fatigue occurs in a few minutes. glycogen and glycolysis are the primary sources of reserve energy. amino acids are not broken down. muscle hypertrophy often occurs. most of the muscle's energy is produced in mitochondria.

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

The difference in the action when comparing the biceps brachii to the flexor carpi radialis, is the shapes of the two muscles differ. one muscle flexes the arm and the other extends the arm. one of these muscles is voluntary while the other is involuntary. one muscle flexes the hand at the wrist and the other flexes the entire forearm. one moves the ulna and the other moves the radius.

one muscle flexes the hand at the wrist and the other flexes the entire forearm

The additional oxygen required during the recovery period to restore the normal pre-exertion levels is called the aerobic oxygen conversion. anaerobic oxygen threshold. refractory oxygen amount. oxygen debt. aerobic oxygen threshold.

oxygen debt

A sheath of connective tissue surrounding a bundle of striated muscle fibers is called sarcoplasmic reticulum. perimysium. epimysium. endomysium. sarcolemma.

perimysium

Botulism is a viral illness. is usually tied to a genetic predisposition. is the result of an attack on acetylcholine receptors by the immune system. results from the loss of acetylcholine receptors at the motor end plate. results from a bacterial toxin that prevents the release of acetylcholine at the axon terminals.

results from a bacterial toxin that prevents the release of acetylcholine at the axon terminals

The heart has to be able to regulate its contractions. Heart muscle, unlike skeletal muscle, cannot go into a tetanus. This is because the heart uses aerobic metabolism. heart muscle contracts faster than skeletal muscle. heart muscle cannot use glycogen. the heart muscle has to be able to consistently contract and pump blood in a controlled fashion. heart muscle is not resistant to fatigue.

the heart muscle has to be able to consistently contract and pump blood in a controlled fashion

Regarding a skeletal muscle fiber, wherever a T-tubule encircles a myofibril, the tubule is tightly bound to the nucleus. thick filaments. the sarcolemma. the sarcoplasmic reticulum. the endomysium.

the sarcoplasmic reticulum

The muscle that dorsiflexes the foot is the peroneus. soleus. tibialis anterior. tibialis posterior. gastrocnemius.

tibialis anterior

Tom is having difficulty dorsiflexing and inverting his right foot. Which muscle is most likely involved in this problem? soleus plantaris gastrocnemius tibialis anterior flexor digitorum

tibialis anterior

What is the function of the transverse tubule? to transmit electrical impulses to the cell's interior the storage of calcium ions to allow cross-bridge attachment to store sodium ions to produce myofibrils

to transmit electrical impulses to the cell's interior

If the permeability of the motor end plate to Na+ ions increases, the result is A) generation of an action potential at the sarcolemma B) generation of an action potential at the axon terminal C) a release of ACh D) breakdown of ACh

A) generation of an action potential at the sarcolemma

Rigor mortis occurs at death due to a lack of A) cAMP B) DNA C) RNA D) ATP

D) ATP

troponin binds to A) actin B) calcium ions C) tropomyosin D) all of these

D) all of these

The connective tissue that covers each muscle fiber A) endosteum B) perimysium C) epimysium D) endomysium

D) endomysium

Cross bridges form during muscle contraction when myosin comes in contact with active sites on A) troponin molecules B) tropomyosin C) calcium ions D) acetylcholine molecules E) actin molecules

E) actin molecules

Which of these regions shorten(s) during skeletal muscle contraction? A) A band B) I band C) H zone D) both a and b E) both b and c

E) both b and c

The end of the muscle that is attached to the more stationary of the two bones is the A) belly B) fulcrum C) insertion D) fixator E) origin

E) origin

Muscles that work together to cause a movement are A) antagonists B) fixators C) convergent D) prime movers E) synergists

E) synergists

Which of the following is an effect of aging on the muscular system? Scar tissue formation does not occur. Skeletal muscle fibers become smaller in diameter. Tolerance for exercise increases. Muscle fibers contain more myoglobin. Skeletal muscles become more elastic.

Skeletal muscle fibers become smaller in diameter

Which statement regarding skeletal muscle is true? Skeletal muscles are directly, but not indirectly, attached to bones. Skeletal muscles do not contain connective tissue. Skeletal muscles do not contain nervous tissue. Skeletal muscles do not maintain body temperature. Skeletal muscles contain blood vessels.

Skeletal muscles contain blood vessels

Myofibrils are made primarily of epimysium. tropomyosin. ATP and ADP. troponin. actin and myosin.

actin and myosin

Active muscles generate heat and oxygen. blood and sodium. carbon dioxide and heat. sodium and oxygen. oxygen and carbon dioxide.

carbon dioxide and heat

Which of the following muscles acts to flex the finger joints and wrist? flexor carpi radialis flexor digitorum pronator teres brachioradialis flexor carpi ulnaris

flexor digitorum

The area between Z lines is the myofibril. myofilament. sarcolemma. sarcoplasmic reticulum. sarcomere.

sarcomere

The stiffness that occurs at death, when actin and myosin molecules stay linked to each other in a contracted state, is due to a lack of DNA. ATP. cAMP. RNA. tRNA.

ATP

Exhaustion of energy reserves or decline in pH due to production and dissociation of lactic acid causes muscle relaxation. the conduction of neural information to the muscle fiber. muscle contraction. muscle fatigue. the striated appearance of skeletal muscle.

muscle fatigue

Creatine phosphate serves to A) cause the decomposition of ATP B) supply energy to synthesize ATP C) decompose ADP D) synthesize ADP

B) supply energy to synthesize ATP

In a neuromuscular junction, the space between the axon and the muscle fiber is the A) postsynaptic membrane B) synaptic cleft C) motor end plate D) synaptic vesicle

B) synaptic cleft

Which of these units contains the Z line? A) A band B) H zone C) I band D) M line

C) I band

A motor unit is A) all the fibers in one muscle B) all the fibers in one fasciculus C) all the muscle fibers innervated by a single motor neuron D) all the nerves that innervate one muscle fiber

C) all the muscle fibers innervated by a single motor neuron

Each muscle cell is a A) fasciculus B) sarcomere C) fiber D) myofibril E) myofilament

C) fiber

The enlarged areas of the sarcoplasmic reticulum near the T tubules are the A) sarcolemma B) sarcomeres C) terminal cisternae D) troponin molecules E) tropomyosin molecules

C) terminal cisternae

Which of the following is characteristic of cardiac muscle? Cardiac muscle fibers are faster than skeletal muscles. Cardiac muscle cells are striated. Cardiac muscle cells achieve tetany with every contraction. Cardiac muscle fibers are multinucleated. Neurons that innervate cardiac muscle tissue are under voluntary control.

Cardiac muscle cells are striated.

Which of the following occurs when glycolysis produces pyruvate faster than it can be used by the mitochondria? Oxygen is produced. Lactic acid is produced. Lactic acid dissociates into a water molecule and hydrogen. Pyruvate levels drop in the cytoplasm. Pyruvate is converted to sucrose.

Lactic acid is produced.

Why do individual muscle twitches have to be added together, as in summation or tetanus? Not enough ATP is generated by one muscle twitch. There has to be a critical mass of muscle twitches for calcium to be released into the muscle cell. Multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle. Not enough acetylcholine will be produced for contraction without multiple twitches. Only added twitches produce any muscle contraction: A fiber undergoing a muscle twitch does not contract at all.

Multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle