Mastering A+P Muscles Test

The characteristic muscle stiffness associated with rigor mortis is due to the inability of myosin filaments to detach from the active site on actin filaments. What molecule is essential for this detachment? acetylcholinesterase ATP calcium acetylcholine

ATP

What can the nervous system do to increase muscle tension? recruit larger motor units increase the number of active motor units increase stimulation frequency All of the listed responses can increase muscle tension.

All of the listed responses can increase muscle tension.

How is delayed-onset muscle soreness (DOMS) different from muscle fatigue? ANSWER: Delayed-onset muscle soreness involves pain. There may be damage to the sarcolemma. Muscle performance is impaired. Delayed-onset muscle soreness occurs a day or more after the physical exertion.

Delayed-onset muscle soreness occurs a day or more after the physical exertion

Which of these statements about skeletal muscles is FALSE? Their fibers branch. They store nutrient reserves. They support soft tissues. They pull on tendons.

Their fibers branch.

The soleus muscle is very red in color. Which of these statements about soleus muscle fibers is FALSE? ANSWER: They are slow to fatigue. They have a slow twitch speed. They are large in diameter. They are rich in myoglobin.

They are large in diameter.

Why do the disease tetanus and the normal sustained muscle contraction called tetanus share the same name? They are both brought on by bacterial infections. They both eliminate the relaxation phase in the affected muscle fibers. They both enable muscle fibers to reach near maximum tension. All of the listed responses are correct.

They both eliminate the relaxation phase in the affected muscle fibers.

Sarcomere is best defined as __________. actomyosin proteins a repeating functional unit of striated muscle a storage organelle for calcium thick and thin filaments

a repeating functional unit of striated muscle

Which of the following is important to increasing efficiency in tension production? a shortened relaxation phase increasing calcium reclamation lengthening the zone of overlap increasing the latent period

a shortened relaxation phase

During neuromuscular transmission, the axon terminals release __________. calcium ions acetylcholinesterase acetylcholine sodium ions

acetylcholine

Which of the following situations could contribute to prolonged muscle contraction? acetylcholinesterase not being produced cross-bridge formation being reduced infrequent neural stimulus limited availability of calcium ions

acetylcholinesterase not being produced

When a skeletal muscle fiber is at rest, its ATP demands are met by __________. the breakdown of creatine phosphate aerobic metabolism of fatty acids aerobic metabolism of glucose glycolysis

aerobic metabolism of fatty acids

Which of the following is NOT an effect that exercise will have on muscle tissue? higher concentration of glycolytic enzymes an increase in the number of myofibrils an increase in the amount of tension produced when the muscle contracts an increase in the amount of fibrous connective tissue

an increase in the amount of fibrous connective tissue

Muscles are attached to bones by tendons or __________. perimysium superficial fascia ligaments aponeuroses

aponeuroses

Triads in skeletal muscle fibers function in __________. calcium ion uptake neuromuscular transmission relaxation calcium ion release

calcium ion release

Interactions between the thick and thin filaments are prevented by tropomyosin. To make the active sites accessible, __________ ions must bind to __________. calcium, actin sodium, troponin calcium, troponin calcium, myosin

calcium, troponin

Smooth muscle contracts when calcium binds to __________ and activates __________. troponin, myosin light chain kinase calmodulin, myosin light chain kinase troponin, tropomyosin calmodulin, actin

calmodulin, myosin light chain kinase

A muscle producing its maximum tension for a prolonged period is in __________. incomplete tetanus rigor mortis complete tetanus treppe

complete tetanus

Fatigued muscles signify __________. accumulation of pyruvic acid oxygen recovery decreased pH lowered body temperature

decreased pH

Characteristics of skeletal muscle fibers include all of the following EXCEPT that __________. each fiber is striated each fiber is multinucleated each fiber contains a single nucleus skeletal muscle fibers are very large

each fiber contains a single nucleus

Titin is a(n) __________. thin-filament protein calcium-binding protein elastic protein tropomyosin-binding protein

elastic protein

Muscle fibers are directly surrounded by which thin layer of connective tissue? endomysium epimysium perimysium tendon

endomysium

The capillaries that wrap around each muscle fiber are located within the __________. epimysium sarcolemma endomysium perimysium

endomysium

Activities involving eccentric contractions more commonly lead to delayed-onset muscle soreness than concentric or isometric contractions. Which of the following activities is thus a candidate for delayed-onset muscle soreness? extension of the biceps brachii carrying a bowling ball pushing against the wall in the gym flexion of the biceps brachii

extension of the biceps brachii

Cardiac muscles cells have a sarcolemma that is more permeable to calcium, which causes them to __________. form more cross-bridges pump calcium back into the sarcoplasmic reticulum faster have faster contractions than skeletal muscle fibers have contractions that last longer than skeletal muscle fibers

have contractions that last longer than skeletal muscle fibers

Muscle fatigue occurs because of a buildup of __________ and a(n) __________ in pH. creatine phosphate, increase lactic acid, decrease creatine phosphate, decrease lactic acid, increase

lactic acid, decrease

Bacteria that cause tetanus release a neurotoxin. Which of the following components of the neuromuscular junction (NMJ) does this neurotoxin affect directly? myofilaments epimysium sarcolemma motor neurons

motor neurons

What area of the thick filament binds to actin once actin's binding sites are exposed? ANSWER: tropomyosin myosin cross-bridge (head) troponin hinge

myosin cross-bridge (head)

The intercalated disk is NOT a site of __________. neuromuscular transmission myofibril attachment action potential propagation force transmission

neuromuscular transmission

Resting smooth muscle can be stretched without affecting tension development because of its __________. contractility extensibility elasticity plasticity

plasticity

Skeletal muscle does each of these EXCEPT __________. ANSWER: maintain posture produce movement store nutrients pump blood

pump blood

Which of these is NOT a function of smooth muscle? elevating skin hairs adjusting airway diameter churning the stomach contents pushing blood into the great vessels of the heart

pushing blood into the great vessels of the heart

In response to an action potential along the transverse tubules, the __________ release(s) calcium ions into the sarcoplasm. sarcomere sarcoplasmic reticulum troponin molecules motor-end plate

sarcoplasmic reticulum

Which type of muscle tissue has the greatest effect on the body's heat production? smooth skeletal cardiac All of these muscle types have about the same effect on the body's heat production.

skeletal

What type of muscle fibers has the longest endurance? intermediate white fast slow

slow

Increased muscle fiber endurance can be produced by __________. a muscle fiber with a smaller diameter the type of activity performed the length of the muscle fiber the amount of excitation-contraction coupling

the type of activity performed

The muscle action potential penetrates deep into a fiber along the __________. sarcolemma transverse tubules neuromuscular junction sarcoplasmic reticulum

transverse tubules